A few days ago, the World Health Organization issued the “Global Strategy for Accelerating the Elimination of Cervical Cancer”, which promised for the first time to eliminate one type of cancer, that is, cervical cancer. The strategy proposes that by 2030, 90% of girls will be vaccinated with the human papillomavirus vaccine (HPV vaccine) before the age of 15. So, what is the relationship between HPV vaccination and prevention of cervical cancer?
Persistent HPV infection is the main pathogenic factor
It is now clear that persistent infection of certain subtypes of human papillomavirus (HPV) is the most important factor leading to cervical cancer. According to clinical statistics, the risk of cervical cancer for people with persistent HPV infection is dozens or even hundreds of times that of non-infected people.
HPV is a virus that mainly exists in human skin, mucous membranes, and female cervical epithelial cell transition areas, and it is mainly transmitted through sexual contact. But women who do not have sex also need to pay attention, because HPV virus can also be transmitted through contact with objects, but this indirect transmission needs to meet three conditions at the same time: the contact site has mucous membranes or wounds; contact with fresh blood containing the virus and the virus amount It must be enough; the virus must be active. Of course, even if infection does not mean illness, about 80% of people will be infected or exposed to HPV in their lifetime. For most women, HPV infection is often transient, and the body’s own immunity can completely eliminate the virus. However, some people with weakened immunity (about 10%) may have infections that persist.
There are currently more than 100 types of HPV known to humans, which are divided into high-risk and low-risk types. Among them, there are 15 high-risk types, including 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, Subtypes 59, 68, 73 and 82, the highest risk is 16 and 18. HPV16 is associated with 50% of cervical cancers, and HPV18 is associated with 20% of cervical cancers.
Cervical cancer enters the era of primary prevention
Clarifying the cause of cervical cancer naturally provides a prerequisite and basis for prevention. HPV vaccination has become the most effective and cost-effective way to prevent cervical cancer. Cervical cancer has therefore become the only preventable and curable cancer.
In fact, as early as 2016, the former China Food and Drug Administration (CFDA) approved the human papillomavirus (HPV) vaccine to be marketed in China. At present, imported 2-, 4-, and 9-valent, domestic 2-valent HPV vaccines are already on the market in China. The 2-valent HPV vaccine is suitable for women aged 9-45 and can prevent 70% of cervical cancer; the 4-valent HPV vaccine is suitable for 20-45 years of age and can prevent 70% of cervical cancer and 90% of genital warts related to types 6 and 11; 9-valent HPV is suitable for 16 to 26 years old and can prevent 92% of cervical cancer and 90% of genital warts.
The reason for the age limitation of HPV vaccine injection is related to the age of the subjects in clinical trials of the vaccine, and the probability of infection with the virus is also considered on the other hand. It is generally believed that as the frequency of sexual life increases, the possibility of infection with the subtypes covered by the HPV vaccine will gradually increase. Therefore, 26 years old is not an absolute age limit. People with high risk factors still need to be vaccinated against HPV. Of course, as the age increases, the antibodies obtained after vaccination will not be as effective as young people, and it is more recommended to fight early.
Regular screening is necessary
Vaccine is the first step in the prevention and treatment of cervical cancer, but different types of HPV vaccines cover slightly different types of HPV viruses, so vaccination does not mean once and for all. Before vaccinating the HPV vaccine, the public should first receive an effective cervical cancer screening to avoid high-risk human papillomavirus infection after vaccination. The “China Guidelines for Comprehensive Prevention and Control of Cervical Cancer” recommends that the starting time for screening be set at 25-30 years old. After being vaccinated with HPV vaccine, regular inspections should also be carried out for secondary prevention. Currently, effective cervical cancer screening methods include cervical cytology (TCT) and high-risk human papillomavirus (HPV) tests.
Men should also be vaccinated against HPV
It is true that men do not suffer from cervical cancer, but they are the main spreaders of the HPV virus. Because HPV virus transmission methods include: sexual transmission; close contact; contact with the clothing, daily necessities, utensils, etc. of the infected person. Studies have found that the incidence of partners with the same type of HPV type is close to 25%. Therefore, men who get HPV vaccine can protect their partners on the one hand; on the other hand, they can also protect men themselves, because HPV virus can also cause other cancers, such as penile cancer, oral cancer, and anal cancer.