Update on the HPV Vaccine

HPV vaccines are made of only one component—the envelope of the virus that assembles to reproduce its shape. That is why it is called a virus-like particle. Since there is no live genetic material that makes a virus multiply inside a cell, the vaccine cannot give the recipient an HPV disease. This protein stimulates the immune system to produce neutralizing antibodies that block the virus from entering the cells, and to produce immune memory cells that warrant long-term protection for at least 5 years.

Vaccination does not help a person with an established infection, since the virus hides inside living cells during infection. Vaccination may give protection against a strain not contained in the vaccine by the virtue of cross neutralizing antibodies. Research still needs to be undertaken to see if these antibodies protect against diseases. The vaccine is given in three doses to the shoulder muscle. The reaction is the same as for other vaccines: pain at the site of injection, a little nausea or fever. More than 5 million doses have been given, and no major side-effects are currently known.

The National Advisory Committee on Immunization (NACI) and the SOGC recommends that all women aged 9 to 26 be immunized, whether or not they were previously sexually active, or even had a disease linked to the HPV types contained in the vaccines. The best value resides in immunizing girls before they are sexually active. No data from studies in men and women older than 26 are available at this moment so the committee refrains from offering any advice other than see your doctor to discuss the possibilities.

Since these vaccines do not contain all the types of HPV, women should continue regular Pap smear exams following local recommendations. Sexually active women who are already infected still receive full protection against the strain(s) they are not already infected with. Through a federal initiative, $300 million is available to immunize women in Canada, but this amount will only cover a small portion of Canadian women who need the vaccine. Coverage for the vaccine varies from province to province, and according to private insurance arrangements.