HPV vaccination in SA
Prof Lynette Denny advocates that HPV vaccination has the capacity to eliminate cancers associated with HPV and will save literally millions of lives thus it should be strongly supported.
There are multiple types of human papillomavirus (HPV) that have been identified over the years (more than 200) but most types are associated with benign disease, which can be problematic. Regarding cancer though, HPV infection with high-risk types are strongly associated with cancer of the genital tract which include the vulva, vagina, cervix and anus. These types, particularly types 16 and 18, are known to cause at least 70% of cancers that occur in these parts of the body. The most common manifestation is cervical cancer.
Origin of the Pap smear
Over 100 years ago, scientists discovered that cervical cancer was preceded by changes in the skin of the cervix which were neither visible to the naked eye nor productive of symptoms. However, when these cells were removed and examined under a microscope, it became evident that these pre-cancerous changes existed and had a very high potential for progression to true cancer. This is how the Pap smear was developed by Greek physician, Dr George Papanicolaou.
Once applied nationally to women in Europe and the precancerous lesions that were detected were removed, the incidence of cervical cancer dropped dramatically. Sadly though, this technology was never introduced into poorer countries, most of which are located in the global south, especially Africa. Hence large numbers of women have continued to develop cervical cancer and die of the disease, despite it being preventable.
Research led to vaccination
In the past 20 years, many have been involved in research to find cheaper and more accessible ways of preventing cervical cancer as an alternative to the Pap smear. In this process, it became clear that detection of high-risk types of HPV is an excellent alternative to the Pap smear for detection of precancerous lesions.
Once the causal relationship between HPV infection and cervical cancer was established, the hunt was on for a vaccination. Vaccination over the past 100 years has saved literally millions from diseases, such as polio, diphtheria, etc. At current estimates, at least 3 million children are saved per year from vaccination.
HPV vaccination was shown to be highly-effective in preventing HPV in girls and boys who had never been exposed to the virus. These findings were a dramatic addition to the armamentarium for the prevention of cervical cancer.
HPV is transmitted by skin-to-skin contact and the most common way is through sexual intercourse.
The current HPV vaccines are known as preventative (stimulating production of antibodies so that if exposed to the virus, the antibodies will immediately prevent the virus from entering the body).
There are two major types of HPV: high-risk (HR) and low-risk (LR). HR-types are predominantly HPV 16 and 18 along with 12 other types. LR-types which are associated with genital warts, are types 6 and 11, among others. While genital warts aren’t malignant, they cause a huge amount of distress in those affected as treatment often requires radical and mutilating surgery and causes severe psychosocial and sexual dysfunction.
There are three types of HPV vaccines. In SA, we have rolled out the bi-valent HPV vaccine which prevents infection with HPV types 16 and 18. Other countries have rolled out the quadrivalent vaccine which prevents infection from types 6, 11, 16, 18, so provides additional protection against genital warts. The newest of the three vaccines is the nonovalent vaccine which is effective against nine types, including 6, 11, 16, 18. This vaccine is still being rolled out and isn’t yet widely available.
HPV vaccine is safe
There is much data, supported by rigorous testing by the World Health Organisation, that show that HPV vaccination is safe, well-tolerated by girls and boys and highly-effective against HPV infection. Recently two very large follow-up studies have shown that both the bi-valent and the quadrivalent vaccine significantly reduce HPV infection rates and the incidence of precancerous and cancerous types of HPV. This is true in both girls and boys and among people living with HIV.
Initially vaccines were prescribed as three doses: ab initio, then one to two months later and then six months later. It has now been shown to be effective if only two doses are given, ab initio and again six months later. Booster doses don’t appear to be necessary and all available evidence suggests that two doses will give life-long immunity.
MEET THE EXPERT – Dr Lynette Denny
Prof Lynette Denny is the Head of Department Obstetrics and Gynaecology, University of Cape Town/Groote Schuur Hospital. She was awarded the Order of the Baobab in November 2021 for her dedicated service to her country with her ongoing medical research.
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