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Seroprevalence of hepatitis B antibodies among international and domestic university students

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Anita Heywood investigates the prevalence of hepatitis B antibodies in both international and domestic students at a university in Australia

Image courtesy of interviewee. October 8, 2024

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This video video discusses a study focusing on hepatitis B seroprevalence among university students in Australia, particularly aimed at understanding the virus's transmission and vaccination status. Hepatitis B is transmitted through blood and body fluids, with vertical transmission (from mother to baby) being a significant global concern. The virus causes liver inflammation, which can lead to severe complications like cirrhosis and cancer, especially in those infected at a young age.

Australia has a low prevalence of chronic hepatitis B infections, but the number is on the rise due to factors such as aging infected populations and high immigration rates from regions with higher endemicity. The country has implemented an immunization program since the year 2000 and conducts sero surveys to gauge vaccine effectiveness.

The study involved 804 students from the University of New South Wales, with a mix of domestic and international participants. Results showed that 65% of students had detectable antibodies indicating vaccination protection, while about one-third were not protected. The study highlighted the importance of accurate self-reported vaccination status, showing discrepancies in people's understanding of their immunity.

Finally, the text emphasizes the critical role of vaccination efforts targeting university populations, particularly during travel consultations, as young adults are at risk during international travel. It suggests that better engagement and education around vaccination status will be essential for protecting this demographic.

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Here are five key points from the video regarding hepatitis B and its prevalence among Australian university students:

1. **Transmission and Prevalence**: Hepatitis B, transmitted through blood and bodily fluids, is primarily spread through sexual contact and vertical transmission from mother to child. In Australia, the prevalence of chronic hepatitis B infection is low (approximately one case per hundred thousand per year), but it is increasing due to migration from regions with higher endemicity and the aging population of those chronically infected.

2. **Vaccination Efforts**: Australia has implemented an immunization program for hepatitis B since 2000, targeting infants and adolescents. Despite high vaccination coverage in children, a significant portion of young adults in the university population are still not protected, highlighting the need for continued vaccination and awareness efforts.

3. **Seroprevalence Study**: The study sampling 804 university students found that about 65% had antibodies indicative of protection from hepatitis B, likely due to vaccination. Notably, a higher percentage (72%) of domestic students were immune compared to international students (58%), reflecting differences in prior exposure and vaccination programs in their home countries.

4. **Validity of Self-Reported Vaccination**: The study revealed low validity in self-reported vaccination status among students. Nearly half of those who believed they were unvaccinated actually had antibodies, indicating prior protection, while a substantial number of those who thought they were vaccinated were not protected. This underscores the importance of regular screening and verification of vaccination status.

5. **Opportunities for Targeted Vaccination**: The paper highlights the importance of leveraging travel clinics and university settings as key points for educating and vaccinating students. Given that international travel can increase exposure risk for hepatitis B, ensuring vaccination among young adults, particularly before travel, is crucial for both immediate and long-term protection against the virus.

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Here are some key quotes extracted from the video regarding the study on hepatitis B prevalence in an Australian university population:

1. **On Definition and Transmission:**
- "Hepatitis B virus, it's a virus that's present in blood, semen, and vaginal fluids and other body fluids in an infected person... it can be transmitted through sexual contact, but also contact with other blood products like sharing of needles and body piercings."

2. **On Global Transmission:**
- "Globally, actually the most important mode of transmission is actually called vertical transmission... so the mother being infected and passing it on during birth."

3. **Consequences of Infection:**
- "Hepatitis B... causes inflammation of the liver... chronic inflammation of the liver can then go on to lead to cirrhosis of the liver and liver cancer."

4. **Chronic Infection Insights:**
- "Not everyone who's infected becomes chronically infected. Most people are able to clear the infection, so only a small proportion end up being chronically infected."

5. **Prevalence in Australia:**
- "In Australia, it's about one case per a hundred thousand per year... the prevalence of chronic hepatitis B infection in Australia is increasing."

6. **Migration and Hepatitis B:**
- "We're also a really high migrant country... when they migrate, if they're chronically infected, that adds to our prevalence pool as well."

7. **Immunization Program:**
- "We have an immunization program in childhood... immunization coverage... has been high for a long time."

8. **Sero Survey Methodology:**
- "One of the ways that we measure vaccine preventable diseases in the population is to do a sero survey... taking blood samples and testing them for antibodies."

9. **Findings of the Study:**
- "Overall, 65% of the students had detectable antibodies to the surface antigen for hepatitis B... around a third weren't protected."

10. **Self-Reported Vaccination:**
- "Self-reported vaccination status had really low validity... nearly half of them who said they were vaccinated actually were protected."

11. **Recommendations for Vaccination:**
- "Travel consultations is a really important place for checking your vaccination status for a range of vaccine preventable diseases... the earlier we can get people vaccinated, the better."

These quotes capture essential details about hepatitis B, the study's methodology, findings, and the implications for vaccination and public health strategies.

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Paper, we're looking at hepatitis B.

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Um, and so it, the paper focuses on identifying

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what we call seroprevalence

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of hepatitis B virus in an Australian university population,

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hepatitis B virus, it's a virus

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that's present in blood semen and vaginal fluids

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and other body fluids in an infected person.

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Um, and that means it can be transmitted

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through sexual contact, but also contact with other blood,

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products like with sharing of needles

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and body piercings and things like that.

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Um, and globally, actually the most important mode

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of transmission is actually called vertical transmission.

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So that's transmission from mother to baby during birth,

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so the mother being infected

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and passing gun during, during birth.

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And so that globally is the most important, mode

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of transmission and what globally we're trying to reduce

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by having vaccines against hepatitis B.

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So Hepatitis B, the virus itself causes

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inflammation of the liver.

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So if you're chronically infected with hepatitis B,

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you have chronic inflammation of the liver

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and that can then go on, lead to cirrhosis of the liver

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and liver cancer as well.

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Um, and so the, the more at risk you are of,

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of being chronically infected, early in your life,

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the more at risk you are of having longer term impact.

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So we try, we wanna try

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and reduce the amount of infants

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who get Hepatitis B primarily

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because they're the ones that are at highest risk

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of going on to have liver cancer.

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Um, so not everyone who becomes chronically infected, sorry,

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not everyone who's infected becomes chronically infected.

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Um, a lot of people are able, most people are able

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to clear the infection,

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so only a small proportion

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end up being chronically infected.

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Um, and so the ones, they're the ones that we are trying to,

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to prevent or protect in terms

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of hepatitis B virus transmission.

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In Australia, Australia's considered a very low,

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endemic country, which means we have very low amount

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of disease and low transmission.

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Um, so a low number of people who are chronically infected.

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So it's about one case per a hundred thousand per year

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in Australia, and then mostly adults.

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So very few, transmission cases from mother to baby,

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which is, which is great.

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Um, but the prevalence

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of chronic hepatitis B infection in Australia is increasing.

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Um, so one of those reasons is that people live

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for a long time if they're infected.

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And so every year, if there's new cases,

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they build up over time you get a bigger

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pool of infected people.

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But we're also a really high mi migrant country as well,

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and we take a lot of, a lot of people migrate from countries

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that have much higher endemicity

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for hepatitis B virus than than we do.

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Um, and so when they, if they migrate,

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they're chronically infected, that adds

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to our prevalence pool as well.

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So it's important that we still vaccinate,

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hepatitis B in Australia, and then also try

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and prevent,

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chronic infection leading onto liver cancer as well.

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Um, and so one of the risk factors for Australians

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for hepatitis B are when susceptible people,

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so unvaccinated people travel overseas,

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so international travel, particularly for young adults

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where they might, be more likely

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to undertake risk activities like unprotected sex

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or skin piercings, tattooing, those sort of things.

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Um, or even just accidents.

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So blood prone accidents in like traffic accidents in highly

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endemic countries where the health system isn't as good.

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So travel is a really important risk factor as well.

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And the other important component, sort of

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that situates this paper is

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that we have an immunization program in, childhood.

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So a birth dose and in three doses at two, four

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and six months of age,

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that we've had in place since the year 2000.

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And before that we had an adolescent program as well.

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Um, so immunization coverage,

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so the measure about the proportion of children

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who were vaccinated has been high for a long time,

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but when it first started so early two

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thousands, it wasn't that high.

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So around sort of 50 or so percent.

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So there was a big group of people

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who weren't getting vaccinated, at that time.

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Um, and so in terms of this paper, one of the ways that we,

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or one of the ways that you can measure susceptibility

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to vaccine preventable diseases in the population

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is to do a sero survey.

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And that basically just means a SA survey of people's blood.

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So taking a sample of people and taking blood samples

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and testing them for antibodies to the, to the virus.

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Um, and so this is what this paper does.

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It identifies the seroprevalence of Hepatitis B in a group

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of Australian university students.

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So a young adult population, both domestic students, some

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of them born in Australia, some migrating,

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during their childhood, and then also international students

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and based at the University of New South Wales.

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So just conveniently that, that's the group of people

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that we sampled, but it's a, a global university.

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Um, it's a diverse university, you know,

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high migrant city of Sydney.

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Um, so that's our population, people who were studying,

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on campus during the time that we did the survey.

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So we recruited students to come in,

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they answered a questionnaire

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and they also gave a sample of their blood.

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And we did that at our, at our university health clinic.

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Um, so they got all the results, themselves as well.

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So that was a great incentive for students

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to do, the study.

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So they end up finding out what they're immune to.

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So we tested for Hepatitis B,

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but a range of other vaccine preventable diseases.

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So then the students' bloods were tested

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for hepatitis B surface antibody, which is indicative of,

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vaccination, so protection.

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And we also did laboratory testing

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for hepatitis C antibody and hepatitis.

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So that's the core antibody for the, the virus.

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And that's indicative of prior infection.

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So we're able to look whether people had also been infected

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previously and if those that had core antibody positive.

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So they had evidence of that.

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We went on to test for,

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to see whether there was actually still the virus there,

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so whether they were currently infected as well.

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Uh, and then the questionnaire that we asked, we asked

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around self-reported vaccination status, whether

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or not they'd ever been diagnosed with hepatitis B.

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Um, a range, the range of risk activities particularly

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around travel,

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and then also a range of demographics like country of birth,

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because the prevalence

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of hepatitis B is varies across the

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world findings of the study.

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So we recruited 804 students overall.

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So we had bloods on 804 students,

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around half were domestic and half were international.

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Uh, so in terms of previous infection, we found evidence

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of only eight, of our students had prior,

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had evidence of infect prior

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Infection and only one of those were currently infected.

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One of those students were actually

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aware of their status as well.

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So it was not, not new to them.

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Um, and then we, found overall

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that 65% of the students had detectable antibodies

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to the surface antigen for hepatitis B, which means

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that they were protected through likely through vaccination,

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which also meant that

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around a third weren't protected as well.

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Um, in terms of our student body, we had,

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majority of them were born in sort of 1993 to 1999,

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so they wouldn't not have been eligible

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for the infant program, which started in the year 2000,

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but they would've been eligible for our adolescent program

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that was run through our high schools, around around

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that time, if they were born in Australia

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and living in Australia at at the time.

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Um, so in terms of who was more, less likely to be,

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to have evidence of, of prior vaccination,

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so we had high rates of, sero prevalence

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or positivity for antibodies in the

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blood in our domestic students.

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So 72% of them were immune, compared to only 58%

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of our international students.

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Um, and I should say that the majority

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of our international students were from highly endemic

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countries where, you know, every country

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has a vaccination program.

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Um, it's, you know, more important for them

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to have been vaccinated 'cause of the high prevalence.

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A couple of other things that we found were

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that self-reported vaccination status,

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people were more likely to actually be immune,

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whether if they were studying in a health related field,

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which makes sense 'cause we have, vaccination policies

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for going into, into hospitals, et cetera.

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Um, and then also recent travel

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to hepatitis B endemic countries as well.

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Um, and that might lend itself to some sort

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of pre-travel vaccination.

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We did find that self-reported vaccination status had really

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low validity, so people get it wrong sort of both ways.

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Um, and so people may think

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that they're protected against hepatitis B when they're not.

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Um, and so that was an important sort of finding to, to show

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that even if you think you've got a, had a va a vaccine,

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it's good to go and get, screened.

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Particularly, for things like prior

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to international travel.

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Um, so we had 46% of students

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who said they weren't vaccinated, actually had antibodies.

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So, nearly half of them

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who said they were vaccinated actually were protected

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and around, a third of those

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who said they were vaccinated weren't protected.

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So that's one sort of example of where we might wanna,

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highlight to particularly young adults to, come in

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and get, get tested, go to your general practitioner

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and get, get a vaccine.

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Um, it's also a couple of, indicates a couple

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of opportunities for vaccination efforts

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that are highlighted in this paper.

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Um, so travel consultations is a really important, place

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for sort of checking your vaccination status for a range

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of vaccine preventable diseases.

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Um, but it's a time prior to travel

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where you might be more at risk during travel

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and for young adults, who are more likely to, to sort

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of undertake at risk activities. It's

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Also really important

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for their protection now, but for their lifetime.

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So they're gonna travel for the,

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potentially for the rest of their lives.

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If they're vaccinated now they're

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protected for the rest of their lives.

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So, the earlier we can get people the better.

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Um, and the other is for groups of university students.

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So it's actually quite difficult to get a captive group

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of adults once students leave high school.

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There's no sort of one place

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where there's a lot congregation of a lot of adults

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and university is one of those places.

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Um, and so that's a really great opportunity

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for our health services at UNSW

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and at other universities to really highlight vaccination

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and checking, you know, vaccination status,

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for Hepatitis B and other vaccines.

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The next step would be then getting va our young adults

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to go and get vaccinated or get screened and get vaccinated.

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So some of the implications of future research is really

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how do we engage young adults?

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Um, so overall health promotion type research,

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how do we engage young adults to get them

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to consider their vaccination status?

Seroprevalence of Hepatitis B in Australian University Students

00:00:00 - Paper, we're looking at hepatitis B. and so it, the paper focuses on identifying what we call seroprevalence of hepatitis B virus in an Australian university population, hepatitis B virus, it's a virus that's present in blood semen and vaginal fluids and other body fluids in an infected person. and that means it can be transmitted through sexual contact, but also contact with other blood, products like with sharing of needles and body piercings and things like that. and globally, actually the most important mode of transmission is actually called vertical transmission.

00:00:34 - so the mother being infected and passing gun during, during birth. And so that globally is the most important, mode of transmission and what globally we're trying to reduce by having vaccines against hepatitis B. So Hepatitis B, the virus itself causes inflammation of the liver. So if you're chronically infected with hepatitis B, you have chronic inflammation of the liver and that can then go on, lead to cirrhosis of the liver and liver cancer as well. and so the, the more at risk you are of,

00:01:06 - the more at risk you are of having longer term impact. So we try, we wanna try and reduce the amount of infants who get Hepatitis B primarily because they're the ones that are at highest risk of going on to have liver cancer. so not everyone who becomes chronically infected, sorry, not everyone who's infected becomes chronically infected. a lot of people are able, most people are able to clear the infection, so only a small proportion end up being chronically infected. and so the ones, they're the ones that we are trying to, to prevent or protect in terms of hepatitis B virus transmission.

Rising Hepatitis B Prevalence in Australia: A Challenge Amid Low Endemicity

00:01:37 - endemic country, which means we have very low amount of disease and low transmission. so a low number of people who are chronically infected. So it's about one case per a hundred thousand per year in Australia, and then mostly adults. So very few, transmission cases from mother to baby, which is, which is great. but the prevalence of chronic hepatitis B infection in Australia is increasing. so one of those reasons is that people live for a long time if they're infected. And so every year, if there's new cases, they build up over time you get a bigger

00:02:08 - But we're also a really high mi migrant country as well, and we take a lot of, a lot of people migrate from countries that have much higher endemicity for hepatitis B virus than than we do. and so when they, if they migrate, they're chronically infected, that adds to our prevalence pool as well. So it's important that we still vaccinate, hepatitis B in Australia, and then also try and prevent, chronic infection leading onto liver cancer as well. and so one of the risk factors for Australians for hepatitis B are when susceptible people,

00:02:40 - so international travel, particularly for young adults where they might, be more likely to undertake risk activities like unprotected sex or skin piercings, tattooing, those sort of things. or even just accidents. So blood prone accidents in like traffic accidents in highly endemic countries where the health system isn't as good. So travel is a really important risk factor as well. And the other important component, sort of that situates this paper is that we have an immunization program in, childhood.

Immunization Coverage and Seroprevalence Study in Australian University Students

00:03:12 - and six months of age, that we've had in place since the year 2000. And before that we had an adolescent program as well. so immunization coverage, so the measure about the proportion of children who were vaccinated has been high for a long time, but when it first started so early two thousands, it wasn't that high. So around sort of 50 or so percent. So there was a big group of people who weren't getting vaccinated, at that time. and so in terms of this paper, one of the ways that we,

00:03:42 - to vaccine preventable diseases in the population is to do a sero survey. And that basically just means a SA survey of people's blood. So taking a sample of people and taking blood samples and testing them for antibodies to the, to the virus. and so this is what this paper does. It identifies the seroprevalence of Hepatitis B in a group of Australian university students. So a young adult population, both domestic students, some of them born in Australia, some migrating, during their childhood, and then also international students

00:04:14 - So just conveniently that, that's the group of people that we sampled, but it's a, a global university. it's a diverse university, you know, high migrant city of Sydney. so that's our population, people who were studying, on campus during the time that we did the survey. So we recruited students to come in, they answered a questionnaire and they also gave a sample of their blood. And we did that at our, at our university health clinic. so they got all the results, themselves as well. So that was a great incentive for students

Assessment of Hepatitis B Immunity and Infection in University Students

00:04:45 - So they end up finding out what they're immune to. So we tested for Hepatitis B, but a range of other vaccine preventable diseases. So then the students' bloods were tested for hepatitis B surface antibody, which is indicative of, vaccination, so protection. And we also did laboratory testing for hepatitis C antibody and hepatitis. So that's the core antibody for the, the virus. And that's indicative of prior infection. So we're able to look whether people had also been infected previously and if those that had core antibody positive. So they had evidence of that.

00:05:16 - to see whether there was actually still the virus there, so whether they were currently infected as well. and then the questionnaire that we asked, we asked around self-reported vaccination status, whether or not they'd ever been diagnosed with hepatitis B. a range, the range of risk activities particularly around travel, and then also a range of demographics like country of birth, because the prevalence of hepatitis B is varies across the world findings of the study. So we recruited 804 students overall. So we had bloods on 804 students,

00:05:49 - so in terms of previous infection, we found evidence of only eight, of our students had prior, had evidence of infect prior Infection and only one of those were currently infected. One of those students were actually aware of their status as well. So it was not, not new to them. and then we, found overall that 65% of the students had detectable antibodies to the surface antigen for hepatitis B, which means that they were protected through likely through vaccination,

Vaccination Status and Immunity Among University Students

00:06:18 - around a third weren't protected as well. in terms of our student body, we had, majority of them were born in sort of 1993 to 1999, so they wouldn't not have been eligible for the infant program, which started in the year 2000, but they would've been eligible for our adolescent program that was run through our high schools, around around that time, if they were born in Australia and living in Australia at at the time.

00:06:52 - to have evidence of, of prior vaccination, so we had high rates of, sero prevalence or positivity for antibodies in the blood in our domestic students. So 72% of them were immune, compared to only 58% of our international students. and I should say that the majority of our international students were from highly endemic countries where, you know, every country has a vaccination program. it's, you know, more important for them to have been vaccinated 'cause of the high prevalence.

00:07:21 - that self-reported vaccination status, people were more likely to actually be immune, whether if they were studying in a health related field, which makes sense 'cause we have, vaccination policies for going into, into hospitals, et cetera. and then also recent travel to hepatitis B endemic countries as well. and that might lend itself to some sort of pre-travel vaccination. We did find that self-reported vaccination status had really low validity, so people get it wrong sort of both ways. and so people may think

Importance of Vaccination Awareness Among University Students

00:07:53 - and so that was an important sort of finding to, to show that even if you think you've got a, had a va a vaccine, it's good to go and get, screened. Particularly, for things like prior to international travel. so we had 46% of students who said they weren't vaccinated, actually had antibodies. So, nearly half of them who said they were vaccinated actually were protected and around, a third of those who said they were vaccinated weren't protected. So that's one sort of example of where we might wanna,

00:08:23 - and get, get tested, go to your general practitioner and get, get a vaccine. it's also a couple of, indicates a couple of opportunities for vaccination efforts that are highlighted in this paper. so travel consultations is a really important, place for sort of checking your vaccination status for a range of vaccine preventable diseases. but it's a time prior to travel where you might be more at risk during travel and for young adults, who are more likely to, to sort

00:08:54 - Also really important for their protection now, but for their lifetime. So they're gonna travel for the, potentially for the rest of their lives. If they're vaccinated now they're protected for the rest of their lives. So, the earlier we can get people the better. and the other is for groups of university students. So it's actually quite difficult to get a captive group of adults once students leave high school. There's no sort of one place where there's a lot congregation of a lot of adults and university is one of those places. and so that's a really great opportunity

Engaging Young Adults in Hepatitis B Vaccination Awareness

00:09:48 - and at other universities to really highlight vaccination and checking, you know, vaccination status, for Hepatitis B and other vaccines. The next step would be then getting va our young adults to go and get vaccinated or get screened and get vaccinated. So some of the implications of future research is really how do we engage young adults? so overall health promotion type research, how do we engage young adults to get them to consider their vaccination status?

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