HPV vaccine: why aren’t Canadians buying in?

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Publication Date: 
Mon, 2013-06-03

Diane Harper, professor of Medicine at the University of Missouri, was a lead researcher in the development of HPV vaccines and involved in clinical trials for both vaccines. In an interview in January 2012 for Medscape Medical News she raised the issue of the duration of protection.

Harper explained that HPV vaccines must maintain a near 100 per cent efficacy for a full 15 years, at a minimum, for cervical cancer to be prevented. “If we vaccinate 11- and 12-year-olds and Gardasil only lasts 10 years, then 21- and 22-year-old women are no longer protected.”  She had discussed this issue as early as 2009 in an article published in Current Opinion in Obstetrics and Gynecology. “No substantial public health decrease in cervical cancer will occur until at least 70 per cent of the female population is vaccinated and then the maximal reduction will not be seen until there has been continuous protection in at least 70 per cent of the female population for at least 60 years” [my emphasis].

Consider the 70 per cent reduction of cervical cancer in industrialized countries in the past 50 years since the introduction of Pap tests.

In January 2012, an update on HPV vaccines, referred to above, was issued from the National Advisory Committee on Immunization (NACI) and posted on the Public Health Agency of Canada (PHAC) website. They acknowledge there are still some unknowns, most notably, how long protection lasts and whether a booster will be needed. In terms of immune response, the report states “the immune correlates of protection against HPV infection/disease are unknown at this time”; it is, however, true that the vaccine will offer higher protection against future HPV infection than a person’s own immune system would after clearing one.

The question of immune response is important in light of Diane Harper’s question about the public health benefits. Because most cervical cancers (67 per cent) occur in women aged 30 to 59, with the average age at diagnosis being 47, it is worth noting that the PHAC report states: “studies have shown that while peak risk for HPV infection is within the first five to 10 years of the first sexual experience, a second peak” in infections is observed in women 45 and older. If these are new infections, will these women still be protected? Current Merck-Frosst ads target adult women up to age 45.

There is some good news for vaccine proponents on this front. For women who had already had one bout of HPV-related disease, a March 2012 study published online in the British Medical Journal revealed that the HPV vaccination substantially reduced the risk of developing HPV disease in the future.

Have questions been answered?

Back in 2007, Women and Health Protection and the Canadian Women’s Health Network (CWHN) responded to the announcement of a national vaccine campaign by raising questions, in particular about what they considered to be the premature nature of the campaign. A year after the first paper, they insisted there were still unanswered questions (see article in Network). To assist beleaguered parents in their decision-making process, they published an educational fact sheet.

The 2007 statement questioned the haste with which the government implemented this very expensive program, particularly given the drop in the incidence rates of cervical cancer in Canada since the introduction of cervical Pap screening. In fact, more recently, Swedish researchers found detecting cervical cancer early with Pap smears improves the survival rate.

While any case of cervical cancer is cause for concern, then, as now, there was no epidemic of cervical cancer. In 2011, the Canadian Cancer Society listed four cancers as accounting for 54 per cent of all cancers diagnosed in Canada. Cervical cancer was not amongst them. In 2011, there were 1,300 new cases of cervical cancer representing seven cases per 100,000.

In an interview she gave to Maclean’s magazine in 2007, shortly after the introduction of the vaccine program epidemiologist Abby Lippman noted that the women who are most affected by cervical cancer in Canada do not have adequate access to regular Pap screening, follow-up and treatment. This is especially the case for  marginalized, Aboriginal and poor women. According to a 2009 report from the Assembly of First Nations “participation in these [Pap screening] programs is lower for First Nations than for the general population in nearly all areas of Canada.”

The role of Pap tests and follow-up

Even without vaccination, cancer of the cervix is considered to be one of the most preventable cancers because of the high success rate when lesions are caught by Pap testing and treated in time.

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