Studies have shown that two, instead of three doses, of the HPV vaccine may be enough to prevent the virus
On Monday the 25th of August, the 29th International Papillomavirus Conference came to a close in Seattle, USA. Amongst the most hotly debated topics at the conference was lowering the number of doses of the vaccine to boost adherence rates.
Dr.Silvina Arrossi, head of the national program for cervical cancer in Argentina, has said that ‘everything indicates that we will go from a three-dose program to a two-dose program.’
Dr.Arrossi suggests that if fewer doses of the vaccine are just as effective than the standard three dose programme, than this will have a positive impact on adherence rates, and it will be more cost effective for health care systems.
Although the standard three dose programme of the HPV vaccine has been show to be 100% effective, global adherence rates for the three doses are low. A CDC report found that only 38 percent of girls between the ages of 13 and 17 have received all three doses of the HPV vaccine. In teenage boys, this figure is even lower, with only 14 percent completing the three doses of treatment.
So far, just two studies have been published suggesting that two doses of the HPV vaccine may be just as effective as three. These studies have prompted the WHO to recommend that girls who receive and respond well to the vaccine will receive sufficient protection from two doses.
Despite these welcome recommendations, it has been noted that for just two doses of the vaccine to be effective, the time spacing of administration must be just right. In a standard three dose treatment, the first dose is administered at 0 months, with the second dose being administered two months after. Finally, the third dose is administered 6 months after the first dose.
Dr.Denise Galloway, whose research has been instrumental in the development of the HPV vaccine, has said that if only two doses of the vaccine are to be administered, then the first dose should be administered at 0 months, and the second dose should be administered at 6 months. This allows sufficient time for the immune system to develop a memory response.
Despite these discussions, a two-dose programme has still mot been approved by the US FDA.
Perhaps future studies confirming the effectiveness of two doses of the vaccine will prompt widespread adoption of a two-dose HPV vaccine plan.
Read more about it here: The HPV cancer vaccine: Are two doses as good as three?