AllergyNet Australia

We are pleased that Dr Julia Brotherton has taken the time to answer our questions on HPV vaccination. Dr Julia Brotherton is Medical Director of Australia’s National HPV Vaccination Program Register

Dr Brotherton is a member of the HPV Implementation Working Group and is currently undertaking a PhD on HPV vaccination in Australia. For the past eight years she has been involved in research and policy development informing the implementation and evaluation of HPV vaccination programs in Australia.

Here are the questions and her answers:

Electron micrograph of HPV virus. NIH-Visuals Online# AV-8610-3067. Public domain

1. What exactly is HPV? How does infection occur? How does someone know if they have it?

HPV, or Human Papillomavirus to give it its full title, is a very common and usually harmless virus. In fact it is so common that it really is a normal part of being a human being to meet and usually clear several types of HPV in your lifetime. Infection with one of the 40 or so types of the virus that can infect the genital area usually occurs during sex or skin-to-skin genital contact. Most of the time you will never even know that you were infected as generally acute infection causes no symptoms – unless you have one of the types that can cause genital warts (fleshy lumps that appear on the genital area) .

Most of the time HPV will be detected by your immune system and cleared by your body without any treatment within a year. The importance of HPV lies in the fact that sometimes people with an HPV infection can’t clear the virus and it remains hidden in their cells. Over time the virus can cause abnormalities to develop in the cells. For example these are the changes that a Pap test picks up in a woman’s cervical cells.

If left for long enough (usually many years) sometimes these changes can develop into cancer. Cancers that can be caused by HPV in this way include cancer of the cervix (neck of the womb), other genital cancers of the anus, vagina, vulva, and penis, and some types of throat cancers.

2. Are there any high-risk groups for HPV infection?

It is estimated that four out of five people will have a HPV infection at some point in their lives. Many people catch HPV from their first sexual partner, without ever knowing it. Anyone who is sexually active (and that’s most of us at some point!) is at risk of contracting HPV.

3. What is the link between HPV and cancer? What types of cancer are linked to HPV? If HPV were eradicated, would those cancers still occur?

Of the 40 HPV types that affect the genital tract, 15 are designated as ‘high-risk’ types associated with the development of cervical cancer, anogenital diseases such as vulva, vaginal, penile and anal cancers and the cell changes that occur before actual cancer, as well as cancers of the head and neck. Practically all cases of cervical cancer are caused by HPV, about 80% of anal cancers, 40-50% of penile, vulval and vaginal cancers and 30% of head and neck cancers. HPV types 16 and 18 cause 70-80% of all cervical cancers, and about 90% of the other cancers. If HPV were eradicated we would see a massive drop in the number of these cancers occurring, with virtual elimination of cervical cancer.

Pap (cervical) smear. Normal cells on left; HPV-infected cells with mild dysplasia (precancer) on right. Ed Uthman, MD. 20 July 2006. Public domain

4. Is there proof that HPV vaccination prevents infection and prevents cancer?

Large clinical trials (of nearly 20,000 women) demonstrated that the vaccine is remarkably effective (close to 100%) at preventing HPV infection with the HPV types that it is designed to protect against (these are types 16 and 18, which cause most cancers due to HPV, and types 6 and 11, which cause most genital warts). The trials did show though that the vaccine does not treat HPV once you are already infected with it – that is once it is already inside your cells. This is why it is really important to try to vaccinate people before they become sexually active and meet HPV infection for the first time.

The trials also looked at whether the vaccinated women developed pre-cancerous cell changes of the cervix due to HPV at the same rate as the unvaccinated women by conducting regular Pap tests. They found that the vaccine was strongly protective (>90%) against pre-cancerous cell changes caused by the HPV types the vaccine protects against. Those women who had changes that needed treatment in the trial were treated, as of course it would be unethical to allow cancer to develop in these women.

As we know from Pap screening programs around the world that treating these abnormalities prevents cancer developing, it has been accepted by the World Health Organisation that preventing these cell changes through HPV vaccination will also prevent cancers from developing. Similarly a large trial in men has shown that HPV infection and cell changes of the penis and anus can be prevented through vaccination.

5. What is in the vaccine? Can you catch HPV infection from the vaccine?

The vaccine doesn’t contain any live or killed virus so there is no possible way you can catch HPV through vaccination. Instead the vaccine is cleverly made up to look like the virus, which stimulates your body to produce antibodies that will protect you if you ever do meet the real virus. These ‘virus-like particles’ in the vaccine are made of one protein which is a normal part of the virus shell. It was Professor Ian Frazer’s laboratory in Queensland that helped pioneer the creation of these particles allowing the development of the vaccine.

6. What are the side effects of HPV vaccination?

Like most vaccinations, the HPV vaccine can cause some mild side effects such as soreness, swelling and redness at the injection site, or a mild temperature. These signs indicate that your body is producing an effective immune response to the vaccine. Sometimes people can also feel faint when given a vaccine, including HPV vaccine. If this happens it is important to lie down and rest until the feeling passes.

The most serious side effect that has been observed following HPV vaccination is anaphylaxis (a serious allergic reaction): after any immunisation a person should always stay for observation for 15 minutes. Fortunately this is very rare and can be effectively treated.

The current vaccination program includes safety monitoring to detect and manage important side effects. With any vaccination, it is important that any side effects are reported to the Therapeutic Goods Administration (TGA) in Australia (and equivalent agencies in other countries). I would encourage GPs to notify side effects to their health authority. In Australia, information on how to report side effects is available by visiting the TGA website at www.tga.gov.au/consumers/problem.htm. Alternatively, you can report a problem or side effect by contacting the Adverse Medicine Events Line on 1300 134 237.

7. How long does immunity last?

So far we know that the vaccine remains effective after 8.5 years, with no cases of pre-cancerous Pap test results due to the HPV types covered by the vaccine reported among vaccinated women. Because antibody levels appear to be stable, it is highly likely that protection will be long lasting but this is being closely monitored in case a booster dose is ever needed.

8. Should regular Pap tests continue in women who have had the HPV vaccination? If so, why?

Yes. Women over the age of 18 who are, or who have ever been, sexually active need to have regular Pap tests even if they have been vaccinated against HPV. The HPV vaccine does not protect against all HPV types that can cause cervical cancer. Pap tests detect abnormal changes in the cells of the cervix and if abnormal changes are found, further tests will be done to see if treatment is needed.

9. Which countries in the world recommend HPV vaccination?

HPV vaccination has been approved and recommended in 100 countries and is supported by the World Health Organisation. The immunisation program is in its 7^th year in Australia and the USA, with other developed countries such as the UK, France and Germany close behind in providing their populations with the vaccine.

10. Some groups in the USA claim that HPV vaccination will promote increased sexual behaviour. Is there any evidence that this occurs?

No. Not only is it well established that fear of HPV is not a barrier to becoming sexually active amongst adolescents, studies have now shown no difference in the time to onset of sexual activity between vaccinated and unvaccinated girls.

11. Are there any children who should NOT receive HPV vaccination?

Children should not receive the HPV vaccine if they have had a serious allergic reaction (anaphylaxis) to a previous HPV vaccine, yeast or any other vaccine components (aluminium, sodium chloride, L-histidine, polysorbate and sodium borate). The vaccine is not recommended for pregnant women.

12. Can a sexually-active older person benefit from the vaccine?

The HPV vaccine is most effective when given before a person is exposed to the HPV virus, that is, before they become sexually active. People who are sexually active may also benefit from the vaccine but they may get less benefit from it since they may have already acquired one or more HPV types covered by the vaccine.

13. Are there any comments that you would like to add?

These really are exciting times for cancer prevention. Australia has been the first country to see big falls in genital warts, HPV infections and pre-cancerous Pap test abnormalities since we introduced the HPV vaccination program for women in 2007. Now we are extending the program to boys so that we can reduce the circulation of these cancer causing viruses still further. Not only will the vaccine protect a boy’s future partner(s) from HPV but will also provide direct protection for him against infection with HPV and dramatically reduce his lifetime chance of developing HPV associated cancers himself.

I’m often asked why we have to vaccinate in the first year of high school and why can’t it be later (I think this reflects our own discomfort as parents about imagining our children ever becoming sexually active!). There are two main reasons really. Firstly, as explained above, the vaccine only works to prevent infection with HPV. Because it can’t be treated once you have it, from a population perspective the best way to control the spread of HPV is to protect people before they are exposed to the virus and that is before sexual activity.

The median age of first sexual intercourse in Australia is 16, so vaccinating at 12-13 years will achieve this. Secondly girls and boys at 12-13 years produce wonderful antibody responses to the vaccine so it is also an ideal time to maximise their protection against HPV using their young and healthy immune systems. A third practical reason is that, as I’m sure you can imagine, it is a bit easier to provide all three doses of vaccine, which are needed for protection, to kids at age 12-13 rather than to 16 year olds.

Thank you Dr Brotherton. AllergyNet Australia endorses HPV vaccination. Discuss with your doctor.

*The first two illustrations in this post were selected by AllergyNet Australia. The third illustration was supplied by Australia’s National HPV VAccination Program.