HPV vaccine to prevent cervical cancer

HPV vaccines offer protection against the types of HPV that are most likely to cause cervical cancer. Infections with these viruses can cause cells to change and possibly develop into cancer. One of the available vaccines can prevent genital warts (condylomas) too. Although these warts are often unpleasant, they aren't dangerous.

The vaccines can reduce the number of women with abnormal cervical cells that have changed so much that they are likely to develop into cancer (also known as high-grade dysplasia, or CIN 3). This suggests that the vaccines also provide protection against cervical cancer in the long term.

The HPV vaccines that are available in Germany are called Cervarix and Gardasil 9. Cervarix provides protection against HPV types 16 and 18, which are responsible for about 60 to 70% of all cases of cervical cancer. It doesn't offer any protection against genital warts. Gardasil 9 provides protection against a total of nine HPV types which are responsible for about 75 to 90% of all cases of cervical cancer. It also offers protection against genital warts.

HPV vaccines don't have any effect on pre-existing HPV infections or genital warts.

In Germany, HPV vaccines are offered to girls and boys between the ages of 9 and 14. The costs are covered by statutory health insurers. Some insurers cover the costs for women above this age too. Girls over 14 who haven't had the vaccine should be vaccinated by their 18th birthday at the latest. In order to prevent HPV infections through early sexual activity, it is recommended that young people have the vaccine as soon as possible.

In boys, the vaccine offers protection from cancer of the penis and anus, and Gardasil 9 can prevent genital warts too. These diseases are often caused by the same types of HPV virus that lead to genital warts and cervical cancer in girls and women. What's more, vaccinated boys won't pass the HPV viruses on to others.

The vaccine is injected into a muscle in the upper arm. It doesn't contain viruses that are able to reproduce inside the body. Instead, it contains proteins that are like the outer coat of HPV viruses. Although the vaccine can't cause an infection, it still triggers a response from the body's immune system. Protective antibodies are made as a result.

HPV vaccines usually involve two injections that are given five months apart. If the second injection is given before the five months are up, a third injection has to be given a few months later. Three injections are also needed if the person is older than 14 when they have the first injection.

Research has shown that HPV vaccines are very good at preventing HPV infections caused by the viruses that they target. This reduces the likelihood of cervical cells changing and becoming abnormal, and also lowers the risk of cervical cancer.

If the protection lasts a long time, the following could be expected:

• Without an HPV vaccine: About 30 out of 1,000 women would develop cervical cancer at some point in their lives – if they don't go for cervical screening.
• With an HPV vaccine: About 10 out of 1,000 women would develop cervical cancer at some point in their lives – if they don't go for cervical screening.

In other words, HPV vaccines could prevent cervical cancer in about 20 out of 1,000 women.

They would also prevent the need for surgery to remove pre-cancerous abnormal tissue. This is because women with high-grade dysplasia (abnormal cervical tissue with cells that have changed a lot) have such a high risk of cervical cancer that they are generally advised to have the abnormal tissue removed.

One of the vaccines, Gardasil 9, also greatly reduces the risk of genital warts.

The effectiveness of the vaccine will depend on whether the person already has an HPV infection when they are vaccinated. It is less effective in people who have already been sexually active.

It is currently not clear whether the vaccine offers long-term protection or whether it will have to be given again (booster shot) at some point. The studies on girls and women lasted eight years at the most. The vaccine continued to offer protection during that time. This suggests that the vaccine is effective in the long term too. But because cervical cancer usually develops over several years or several decades, more time is needed to be sure.

HPV vaccines weren't found to cause any serious side effects in the studies on girls and women. They may lead to various temporary skin reactions where the shot was given, including pain (in 90 out of 100 vaccinations), skin redness (in 30 out of 100 vaccinations), and swelling (in 40 out of 100 vaccinations). Problems such as indigestion, headaches, tiredness or muscle pain may also occur, but are less common.

Some young people may faint after having an injection. Because of this, it's important to stay at the doctor's for about 15 minutes afterwards.

People who have a fever or infection shouldn't be vaccinated. If the first vaccination causes an allergic reaction, a second dose shouldn't be given.

Authorities worldwide have been monitoring reports of possible side effects of HPV vaccines since their use was approved. Due to the sheer number of girls and boys who are vaccinated, it is to be expected that some people will coincidentally have unrelated severe illnesses after having an HPV vaccination. According to authorities like the World Health Organisation (WHO) and the European Medicines Agency (EMA), there is no reason to believe that the illnesses that developed after receiving the HPV vaccine were actually caused by the vaccine.

Research has shown that one of the vaccines (Gardasil 9) effectively prevents genital warts and ulcers that are caused by HPV viruses. But the studies didn't last long enough to be able to say how well the vaccine prevents cancer of the penis and anus over the long term. These types of cancer are very rare, too.