Human Papillomavirus vaccine: one that can prevent a cancer

This article has been written as a fervent plea to the parents of little girls of the eligible age group. Please make sure that your precious daughters get this vaccine. It will be an investment for their happiness in the future.

By Dr B. J. C. Perera

All vaccines by definition are substances that are used to stimulate immunity against a particular infectious disease or a specific causative organism. Such vaccines are used to prevent the occurrence of the said diseases in humans and animals. Several vaccines have been introduced to combat such infectious diseases over the last few decades. In some countries, the use of some of these vaccines has led to the elimination of dreaded diseases like Diphtheria, Tetanus, Whooping Cough or Pertussis, Polio, Measles, German Measles or Rubella, just to name a few.

Sri Lanka has a very efficient and inherently equitable system that looks after the Expanded Programme of Immunisation (EPI) for children and young people. In general, we have been extremely successful in this programme and can boast of over 90 per cent coverage for the vaccination of all children. We have successfully eliminated polio, the last case being confirmed as far back as 1993, and we are free of diphtheria, tetanus, measles and German measles or rubella. The success of the EPI is due to many factors that include government commitment, the unstinted dedication of parents, the promotion of the programme through all media channels and the dedicated work of all grades of healthcare personnel. The very high literacy rate of the populace of our country enables all information regarding vaccination to be most conveniently conveyed to the population. Sri Lanka has been hailed as a country that has achieved so much in this field, but with so few resources. It has been cited as a model to the entire Asian region as well as even the world.

In addition to their undoubted effectiveness in protecting against infective microorganisms, some of these vaccines have other bonus effects. At least two of the vaccines in use today have telling effects in preventing certain cancers. One is the Hepatitis B vaccine. It provides protection against liver cancer. The other is the more recent Human Papillomavirus vaccine (HPV vaccine) which protects females against cancer of the neck of the womb, which is also referred to as the cervix of the womb. That disease is generally referred to as Cervical Cancer.

The Human Papillomavirus (HPV) is sexually transmitted and most people become infected sometime during their lifetime. In the majority, it is soon after becoming sexually active. Most infections are asymptomatic and usually clear up spontaneously, accounting for remission in 90% within two years. Only 10% of persistent HPV infections with certain genotypes of HPV can persist and progress to changes in the cervix. If infection from cancer-causing HPV types persists over 10-15 years, women can go on to develop precancerous lesions that, if left untreated, develop into cervical cancer. This process takes an average of 20-30 years from infection to the development of cervical cancer.

In 1995, Dr Anne Szarewski, a renowned researcher from the United Kingdom, led a team who outlined the role of human papillomavirus in uterine cervical cancer detection and screening. Then the researchers began work on an HPV vaccine. Szarewski was also a chief investigator, principal investigator and author of key HPV vaccine trials and publications, who helped to develop the bivalent HPV vaccine. The word bivalent is used to indicate that it contains two strains of HPV. HPV infections are very common, often with minimal symptoms, but high-risk HPV strains can go on to cause other medical conditions, particularly cervical cancer.

In 2006, the first vaccine for Human Papillomavirus (HPV) to be used globally was approved. HPV vaccination has now gone on to become a key part of the effort to eliminate cervical cancer. According to the available research results, HPV vaccination could reduce the lifetime risk of cervical cancer by 35–80%; the rather wide range being due to several studies with different methods. The vaccine was initially promptly snapped up in the West, especially in the Scandinavian countries. In Sweden, the coverage of the vaccine is over 80 per cent. However, according to the data put out by the World Health Organization (WHO) in November 2022, the human papillomavirus vaccine against cervical cancer has been introduced in just 41 per cent of low-income countries, even though they represent much of the disease burden, compared to 83% of high-income countries. We have a set of 10-year data on the benefits of the vaccine and in certain Western countries, a significant drop in the morbidity and mortality rates of cervical cancer is already evident.

In Sri Lanka, the National Vaccine Summit in January 2015 recommended the usage of the HPV vaccine and the government introduced it in 2017 for girls within the age range of 10 to 13 years. That age group was decided on the premise that to get the best results, we need to introduce the vaccine before sexual activity starts. The vaccine was to be administered to the selected age groups in the schools free of charge and in the fee-levying private sector. To date, the vaccine is not available through the Immunisation Clinics of the Provinces and the MOH Clinics.

NOW HERE IS THE REAL CRUX OF THE MATTER. For a variety of reasons, the coverage of the HPV vaccine in the entire cohort of eligible girls in Sri Lanka is somewhere between 30 and 40 per cent. This is woefully inadequate coverage to get the best possible results, especially when looked upon in the light of over 90 per cent coverage of the other vaccines in the National Expanded Programme of Immunisation. Cervical cancer ranks among the five commonest cancers in women in Sri Lanka. HPV vaccine is just one of two vaccines that can prevent cancers. All children have had the Hepatitis B vaccine which protects against liver cancer, as it is given through the National Programme of Immunisation. But, and this is a BIG BUT, the only other vaccine, the HPV vaccine that can prevent cervical cancer, shows a rather low uptake.

We do need to escalate the uptake rate of the HPV vaccine to at least around 80 per cent to get reasonable benefits in the reduction of the morbidity and mortality that is currently seen in cervical cancer. I think we have to admit that due to very many reasons, the message has not gone through to the general population in the country. When inquiries are made from the mothers of eligible girls, the vast majority of them are not even aware of the existence of this vaccine and more importantly, the future beneficial potential of this endeavour. The age group selected is a rather tricky cohort. They get upset at the drop of a hat. The last thing they want is an injection. They will run away, as fast as possible, to avoid it. Some are so frightened that it is not uncommon to see them faint even at the sight of the syringe and the needle. One way of getting the cooperation of these little girls is to allow either the mother or the father to be present to hold her hand most reassuringly when the vaccine is administered. An additional initiative would be to make it widely available through the Immunisation Clinics for it to be administered to all those who have missed it when it was given in the school. This is particularly important as the vaccine is quite expensive when administered in the private sector.