Global Vaccine Safety

Safety of human papillomavirus vaccines

Extract from report of GACVS meeting of 17-18 June 2009, published in the WHO Weekly Epidemiological Record on 7 August 2009

The Committee reviewed the safety of HPV vaccines. By March 2009, >60 million doses of the quadrivalent or bivalent HPV vaccine had been distributed either as part of national immunization programmes in 21 countries or by private physicians. Data from post-marketing surveillance were reviewed from countries that introduced the vaccine early, from regulatory authorities and from manufacturers. Additional data were reviewed from 4 demonstration studies undertaken in developing countries that were conducted by the nongovernmental organization PATH (the Program for Appropriate Technology in Health) and from recently completed and ongoing studies conducted by manufacturers on the vaccination of young males and the concomitant use of HPV vaccine with other vaccines in young girls.

The accumulating evidence on the safety of HPV vaccines is reassuring. The most common adverse events were reactions at the injection site and muscle pain. Allergic reactions have also been reported. The potential risk of injury after vaccination resulting from dizziness and syncope has been added to the label of 1 of the vaccines. Several different signals were observed in countries introducing HPV vaccination but none, other than syncope, was judged to be causally related to vaccination. The limited data on the inadvertent administration of HPV vaccines shortly before pregnancy or during pregnancy are reassuring. They do not establish a relationship between HPV vaccination and miscarriage, but the data are insufficient to rule out a small effect, in particular if conception occurs shortly after vaccination. The Committee considers that further studies should be encouraged, given the limited data.

The Committee noted with satisfaction that studies on HPV immunization have been initiated in Africa, including some among HIV-positive women. As preparation for introducing HPV vaccines, capacity building for surveillance for adverse events is being addressed. While the safety profile of HPV vaccine is reassuring, the collection of high-quality safety data from different geographical locations and epidemiological settings where the vaccine is being introduced remain a high priority.