By Alan Mozes
FRIDAY, December 27, 2019 (HealthDay News) – In a finding that could make the HPV vaccine more acceptable to many, new research suggests that a single dose can provide as much protection against cervical cancer as Two or three recommended doses.
"The vaccine is extremely effective and can prevent more than 90% of the almost 35,000 cancers caused by HPV each year among men and women," said study author Ashish Deshmukh. He is an assistant professor at the Center for Health Services Research at the University of Texas School of Public Health in Houston.
"And we found that [American] Women who received only one dose of the HPV vaccine obtained benefits similar to those who received two or three doses, "Deshmukh added.
First introduced in 2006, the multidose human papillomavirus (HPV) vaccine can prevent most cervical and anal cancers among children and young adults exposed to the virus. It can also prevent most oral and penile cancers driven by HPV.
However, vaccine coverage has remained low. In the United States, vaccination rates are around 50%. And in developing countries, where the cost per dose of $ 4.50 is often out of reach, rates are a lousy 10%, the researchers said.
An obstacle is stigma around a vaccine linked to sexual activity among young people. Another is that many people are unaware that HPV can cause cancer. And then there is the discomfort and expense of the recommended regimen of two or three doses.
But if a single and successful vaccine could achieve the same goal, much of that last obstacle could be eliminated, the study team noted.
"We were surprised at the magnitude of the benefits," said Deshmukh, whose team's conclusion followed an analysis of diagnostic and HPV vaccination data in more than 1,600 women between the ages of 18 and 26.
All women participated in the US National Health and Nutrition Examination Survey. UU. (NHANES) between 2009 and 2016. Almost two thirds had not been vaccinated. A little over 100 had been inoculated only once. About 125 had received two doses, and almost 400 had received three.
Current vaccine guidelines advise to be vaccinated from 11 or 12 years to 27 years. Those vaccinated before age 15 should receive a second dose between six and 12 months later. Patients with weak immune systems and / or those whose first dose is administered between 15 and 26 years of age receiving three inoculations are recommended, with a second dose 30 to 60 days after the first, and a third dose at six months.
The researchers confirmed that HPV infections were "significantly less prevalent" among people exposed to at least one dose of vaccine.
But there was also "no significant difference" in the risk of HPV infection among those who had taken one, two or three doses.
So, does this definitely mean that one dose of HPV vaccine is enough? No, said Deshmukh.
On the one hand, his team noted that the survey participants fully informed the history of the vaccine, which is less reliable than medical records, and that male patients were not included in the survey. And the team did not track the dosing time or histories of HPV infection.
"[So], we believe that our findings are still early, "said Deshmukh." To change vaccination guidelines to a one-dose schedule, we need conclusive evidence from clinical trials. "Such a trial is underway in both the United States and Costa Rica, he said.
That larger study "will give us a conclusive answer" in terms of the reliability of a one-dose protocol, says Debbie Saslow, director of HPV and GYN cancers with the American Cancer Society in Atlanta. She was not part of the study.
But Saslow expressed little surprise that a dose seems to do the trick.
"However, it probably won't be as effective as two doses," he said. But cost, he emphasized, is probably the biggest vaccination barrier in developing countries. "Therefore, it is likely that in the US we will continue to recommend two doses, but in low-income countries a dose will be recommended."
Anyway, Saslow has a clear message for parents: eventually, almost everyone is exposed to HPV, and the HPV vaccine "is one of the most effective vaccines there is."
He urged Americans to take advantage of a simple means of protection, safe and covered by insurance. "With the HPV vaccine, we just have to vaccinate our children with two vaccines, and then they are protected for the rest of their lives," Saslow said.
The study, which was funded by the US National Cancer Institute. UU., It was published in the December 27 issue of the magazine. JAMA open network.