Women who get one dose of the HPV vaccine, and not the full recommended series of three shots, may have adequate protection against the virus that leads to cervical cancer, according to a new study published this week in Cancer Prevention Research, a journal of the American Association for
Researchers at the National Cancer Institute found that women who received just one dose of the HPV vaccine, which protects against human papillomavirus, which leads to cervical cancer, had antibodies against the viruse that remained in their blood for four years. The findings suggest that a single dose of the vaccine may be enough to generate long-term protection against HPV infection, and cervical cancer.
Last year 53.8 percent of girls between ages 13 and 17 got at least one HPV vaccination, but only only a third of them received all three, said Mahboobeh Safaeian, an investigator for the Division of Cancer Epidemiology and Genetics at the National Cancer Institute involved with the study.
“We wanted to evaluate whether two doses, or even one, of the HPV vaccine could induce a robust and sustainable response by the immune system,” she said. “Our findings challenge previous dogma that vaccines require multiple doses to generate long-lived responses.”
The researchers tested the blood of women who had received one, two and three vaccines, and found that 100 percent of the women in all three groups had antibodies against HPV for up to four years.
Though researchers found that antibody levels among women who received one dose were lower than among those who received three, the levels appeared stable, suggesting that these are lasting responses.
“Our findings suggest promise for simplified vaccine administration schedules that might be cheaper, simpler, and more likely to be implemented around the world,” said Safaeian. This could be especially important in the developing world, where more than 85 percent of cervical cancers occur, and
where cervical cancer is a common cause of cancer-related deaths.
While the findings are promising, more data are needed before policy guidelines change, she said. For instance, the persistence of antibody responses after one dose of Gardasil, the HPV vaccine more widely used in the United States, has not been studied.
Although the studied vaccine, Cervarix, and Gardasil are similar, and both protect against the same types of HPV, there are differences in their manufacturing, so Safaeian said she did not want to speculate.
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