Vaccination against human papillomavirus (HPV) infection is being promoted as beneficial to young teens before they have had sexual contact. The vaccine has demonstrated high level of antibody response especially in women who have not been exposed to the virus. Hence the target group is young girls. By preventing HPV infection, we can prevent deaths from cervical cancer.
The vaccine is almost 100 per cent effective against four types of HPV, two of which are responsible for 70 per cent of all cervical cancers. The vaccine may have cross-protection against some other HPV viruses.
Most common side-effect is pain at the injection site. Otherwise, it is a safe vaccine except recently, concern has been expressed as some cases of anaphylaxis have been reported. Usually, anaphylaxis due to any vaccination is rare, with an estimated incidence of 0.1–1 per 100,000 doses.
Anaphylaxis is a severe acute allergic reaction that is sudden in onset. The skin symptoms are the most common, followed by breathing difficulties and then trouble swallowing. The person goes into shock and by that time it may be too late to save life. Anybody who is in the business of providing vaccinations should be prepared to deal with anaphylaxis. An individual, after receiving any vaccination, should be observed at least for 15 minutes.
In the September 9 issue of Canadian Medical Association Journal (CMAJ), the subject of anaphylaxis after HPV vaccination has been discussed in detail.
A study done in Australia reported that from the 269,680 HPV vaccine doses administered in schools, seven cases of anaphylaxis were identified, which represents an incidence rate of 2.6 per 100,000 doses. They found this to be higher than comparable school-based delivery of other vaccines. The article says, “However, overall rates were very low and managed appropriately with no serious sequalae.” Identified cases of anaphylaxis following vaccination tend to occur less than one hour after vaccination.
The experts do not know why these girls had adverse reactions to the vaccine. The authors of the Australian study say that the estimated rate of anaphylaxis following quadrivalent HPV vaccine was significantly higher than identified in comparable school-based delivery of other vaccines. However, overall rates were very low and managed appropriately with no serious sequelae. None of the patients went into shock. That is good news.
According to CMAJ, in the United States, 15 cases of anaphylaxis or anaphylactoid reactions following HPV vaccination were reported to the Vaccine Adverse Events Reporting System in 2007. As of July 21, 2008, 11 cases have been reported in 2008. Over 13 million doses of this vaccine had been distributed as of the end of 2007. Although there may be underreporting, the rate of about one case per one million vaccinations is consistent with the rate of anaphylaxis following several other vaccines.
People opposed to this program would like to delay immunization until a young woman is sexually active. Unfortunately, HPV infection can occur with the first sexual intercourse, and half of Canada’s young women become sexually active by age 16.
What about the boys? Some young boys are sexually active as well. They show up with venereal warts from HPV infection. CMAJ says Canada and other industrialized countries (except for Australia) have only approved vaccination for females thus far, because studies involving males have not been completed. Hence, for now, only immunized women will be protected.
Finally, there is no doubt there is compelling evidence the HPV vaccine is remarkably safe. Preventing cervical cancer is very important. In Canada, an estimated 1300 women will be diagnosed with cervical cancer this year and 380 will die. In spite of years of Pap smears and regular screening, cervical cancer is still prevalent.
Start reading the preview of my book A Doctor's Journey for free on Amazon. Available on Kindle for $2.99!