Fact sheet: HPV vaccine for protection against cervical cancer

Over the past few decades the number of women with cervical cancer has decreased drastically in many countries, including Germany. Yet this kind of cancer is still a life-threatening disease. Human papillomavirus (HPV) infections play a critical role in the development of cervical cancer. There is now a vaccine against some of these sexually transmitted viruses. It targets the most common of the carcinogenic (cancer-causing) viruses but does not provide complete protection against cancer.

What is HPV?

HPV viruses only affect humans, attacking skin and mucous membranes. They can be spread through direct contact with infected skin or membranes. In most cases HPV infections go unnoticed, do not cause any symptoms, and clear up on their own.

So far, more than 100 different types (strains) of human papillomaviruses are known to exist. Some of these can lead to the development of warts (papillomas). About 40 HPV strains infect the skin or mucous membranes in the genital area and are transmitted through sexual contact. They are not spread through body fluids, but through contact with skin and membranes.

Because the viruses are very common, most people who are sexually active will become infected with HPV. It is thought that as many as 80-90% of all sexually active women will have an HPV infection at some point in their lives.

What are the consequences of an HPV infection?

In most people, the body’s immune system destroys the viruses relatively quickly on its own, without any consequences. An infection typically lasts about eight months. However, if the infection is not successfully fought off and the virus stays in the skin or membranes cells, the affected tissue may start to change over time. In women, this typically occurs in the region of the cervix, but it can also occur in the membranes lining the vagina, although this is extremely rare. The cervix is the lower end of the uterus (womb). The lower part of the cervix is referred to as the mouth of the womb, and opens into the vagina.

A number of risk factors other than HPV infections play a role in the development of cervical cancer, like a person’s ethnic origin. The most decisive factor, however, is an HPV infection. Two strains of the virus, known as HPV 16 and 18, are considered to be particularly dangerous. It is estimated that they are involved in the development of 70% of all cervical cancer cases. Infections with carcinogenic HPV viruses have been recognised as a cause of cervical cancer since the 1980s.

Infections with some other strains of HPV viruses can lead to irritating but harmless warts (condylomas) in the genital area. Many of these are not noticeable, others can be felt as small hard bumps with an uneven surface. 90% are caused by HPV strains 6 and 11. About 1% of the population has condylomas, but they are more common in sexually active young people. In 20-30% of all people who have them, the warts disappear on their own without treatment.

How common is cervical cancer?

Cervical cancer affects about 6,200 women every year in Germany. This is about 12 to 14 out of every 100,000 women, and about 3% of all cases of cancer in women in Germany. Most of these women are diagnosed with cervical cancer when they are between the ages of 35 and 55.

In the early stages of the disease, cervical cancer does not cause any noticeable symptoms, so it can only be detected by means of a simple, specific medical examination. A cancerous tumour is considered to be in the early stages of development (an “in situ carcinoma”) if the cancer cells have not invaded the surrounding tissue. About 30-40% of such pre-cancerous changes go away without treatment, but around 12-15% develop into cancer. Because cervical cancer tumours are usually discovered and treated early on, it is difficult to say how they would develop without treatment. The treatment possibilities are good in pre-cancerous and early stages.

How can you protect yourself from HPV infections?

The careful use of condoms provides protection against many sexually transmitted diseases. Yet condom use alone is not enough to protect against HPV infections. Because these viruses are so common, it is very difficult to ensure 100% protection other than by avoiding sexual activity completely.

A vaccine against the HPV types 16 and 18, 6 and 11 became available in 2006. HPV 6 and 11 are not considered to be cancer-causing (carcinogenic) viruses, but they can cause genital warts. The vaccine which goes by the brand name “Gardasil” or “Silgard” provides protection against these four types, but hardly protects against other types of HPV, and does not offer any protection at all against other sexually transmitted infections. This is also true for the other licensed vaccine, marketed under the name of “Cervarix”, which only targets HPV types 16 and 18. “Cervarix” does not protect against genital warts. No published scientific studies have directly compared the two vaccines to see how well they can protect women against pre-cancerous changes. The question of whether boys could or should be vaccinated too is still being discussed. 

In March 2007 the German authorities issued a recommendation that all girls between the ages of 12 and 17 be given an HPV vaccine. In response to this recommendation, the German statutory health insurance funds now cover the vaccine costs for all girls between 12 and 17. Girls and women who are younger or older than this can have the vaccine too, but the statutory health insurance funds do not generally pay for them to have it. 

In order to prevent young women from becoming infected with HPV early on, it is recommended that they be vaccinated before they become sexually active, if possible. But it is not exactly clear at what age it is best to have the vaccine. Most of the research on how HPV vaccines influence the development of pre-cancerous changes was done in women who were 15 years old and above.

How well does the HPV vaccine work?

In many women the vaccine successfully prevents pre-cancerous changes which may develop into cervical cancer. The scientific trials which looked at the vaccine that targets four HPV strains showed that the risk of pre-cancerous changes caused by HPV 16 and 18 is generally low. It was only 2-3% in women who had not been vaccinated, compared to 1-2% in those who had. In other words, the vaccine prevented the development of pre-cancerous changes in about 1 out of every 100 women during the trial. It is assumed that the vaccine works even better in girls and women who have not been infected with HPV – but researchers disagree about the estimates of possible benefit. The vaccine was also shown to reduce the frequency of genital warts from 4% in women who were not vaccinated to 1% in those who were (1 in every 100 women).

According to current knowledge, the protective effect of the vaccine lasts at least five years. It is not yet known whether a booster vaccination is needed after this. The vaccine cannot be used to treat HPV infections or genital warts once women have them.

Because it is not yet known how well the vaccine works in the long term, and because cervical cancer usually develops very slowly, at the moment it is unclear whether the HBV vaccine really lowers the number of people who get cervical cancer. Being so new, there is also no evidence to show whether it reduces the number of women who die from this disease either.

One benefit of having the vaccine is that it can prevent pre-cancerous changes from developing. The diagnosis and treatment of these changes can be very stressful for women. Every year, thousands of women have surgery to remove pre-cancerous tissue – it is not known exactly how many women do though.

You can read more about clinical trials of the HPV vaccine here.

How is the vaccine given?

The vaccine is injected into the muscles of the upper arm. It does not contain any genetic material (DNA) of the viruses. Instead, genetically engineered virus-like particles are used. These have the same outer protein coat as the viruses do, but do not carry any genetic information. The particles activate the body’s immune system and trigger the production of protective antibodies without causing an infection. Depending on the vaccine, the second dose is given one or two months after the first dose, and the third dose is given six months after the first dose.

What adverse effects does the HPV vaccine have?

The adverse effects of the HPV vaccines have been studied in three ways:

• In small safety tests, including with young teenagers
• By information on adverse effects collected in the large trials
• Through monitoring reports of adverse effects from doctors and other health care workers, particularly in the USA

Based on the small, short-term safety tests, the authorities concluded that the vaccines are safe.

No serious adverse effects were reported in the large trials. According to the US authorities, HPV vaccines can cause local skin reactions at the site of injection, such as pain (in 8 out of 10 people), swelling (in 3 out of 10 people) and redness (in 3 out of 10 people). Fever is also among the more common adverse effects (just over 1 in 10 people). Problems such as indigestion, headaches, tiredness or muscle ache may occur but are less common.

The US authorities have set up a monitoring programme to collect data about adverse effects caused by the HPV vaccine. Early results are now available. The authorities say that the results are generally reassuring: given how many millions of girls have now been vaccinated, they believe that the vaccine is reasonably safe. But they do warn that, as with many vaccines in teenagers, there is a risk of fainting soon after having the vaccination. Doctors should therefore monitor girls who get the vaccine for at least 15 minutes afterwards, and the girls should not get up too quickly after having the shot.

It would be inadvisable to inject the second vaccine dose if, for example, the person is ill with a fever at the time when it is due. If the first dose causes an allergic reaction, a second dose may not be given. The possible adverse effects of the vaccine in the long term are not yet known.

What can you do to prevent cervical cancer?

Although the HPV vaccine provides protection against certain types of HPV that can cause cancer, it is not clear to what extent it can prevent cervical cancer. So at this stage it cannot be called a “cancer vaccination” as such, even if an HPV infection sometimes leads to cervical cancer. Both vaccines provide protection against the two most common cancer-causing (carcinogenic) HPV viruses, and they appear to halve the risk of pre-cancerous changes in the short term. 

Researchers still do not agree about how much young women can benefit from the HPV vaccine. Some say there is a great benefit, some say there is a small benefit, and others question the vaccine in general. Further research has to be done to be more certain about all these issues.

The vaccine does not replace regular smear tests for the early detection of cervical cancer. These make it possible to discover and treat pre-cancerous cell changes at an early stage.

As part of a cancer screening programme organised by the statutory health insurance funds, every woman above the age of 20 in Germany is entitled to a smear test or so-called “Pap test” (named after the Greek doctor George Papanicolaou, who developed it) once a year. During this screening test, a doctor removes some cells by gently scraping the membranes lining the mouth and neck of the womb (cervix) using a special spatula and brush. The cells are then “smeared” onto a glass slide and examined under a microscope. If any abnormal cells are found, further tests are needed.

What should be considered when vaccinating girls and young women?

As already mentioned, the vaccine should not be seen as an alternative to regular smear tests for the early detection of cervical cancer and does not provide protection against other sexually transmitted diseases. One of the potential dangers of the vaccine is that it might make young women feel so safe that they do not feel the need to take precautions, such as using condoms, during sexual activity.

Girls and young women should avoid getting up too quickly or doing things like riding a bike immediately after having the vaccine, as there is a risk of fainting.

Because there are still a number of unanswered questions about the HPV vaccine, it is not easy to weigh up the pros and cons. As well as being well informed about the HPV vaccine, it is particularly important for young women to know how they can protect themselves against sexually transmitted diseases and cervical cancer. In our article and leaflet – written especially for girls – we have put together information for girls who are still deciding whether or not to have the vaccine.


Author: German Institute for Quality and Efficiency in Health Care (IQWiG)

© IQWiG (Institute for Quality and Efficiency in Health Care)