Is one dose of HPV vaccine enough against cervical cancer?
New research suggests one does of HPV vaccine indeed might prevent human papilloma virus that can lead to cervical cancer.
Antibodies against HPV found with a single dose of vaccine
Scientists compared women in Costa Rica that received one, two or three injections of Cervarix that protects from two types of HPV to see detect antibody levels that would indicate protection from the virus.
One of the reasons the investigators looked at dosing is because of low rates of women who receive the entire recommended three doses of HPV vaccine.
According to new data women given just one dose of vaccine developed immunity that was higher than women infected with the virus.
“We don’t know what the minimum required [antibody level] might be for protection," said study researcher Mahboobeh Safaeian, of the National Cancer Institute.”
Three doses of the vaccine had been previously recommended based on what’s known about other vaccines and immunity.
The study is significant Safaeian said in a press release. One dose of HPV vaccine is not only cost-effective. It’s also simpler.
In the study, women who received one, two or three doses had antibodies against the cancer causing virus that remained stable for four-years.
However, women given one dose had lower levels of antibodies compared to those who had two or three injections.
Those who received one or two doses six months apart had antibody levels that were 24 times higher than women infected with HPV who received no vaccine.
One dose of Cervarix produced antibodies five to nine times higher than those found in women with HPV infection.
Two doses produced antibody levels comparable to three doses the study found.
Cost of the vaccine is a hurdle in developing countries. The researchers say if one dose would work it would mean more widespread protection.
Twenty percent of women in the study that included 3500 women did not get all three dose of HPV vaccine.
Cervarix protects against two types of HPV. Another vaccine, Gardasil that protects against four types includes protection against the virus that causes genital warts was not investigated in this study.
Despite a push to have young women vaccinated against HPV before they become sexually active, compliance rates are low.
According to the recent CDC “Morbidity and Mortality Report” in 2012 only 53.8 percent of girls age 13 to 17 initiated the vaccine and only 33.4 percent of young women received all three doses.
The finding is published in Cancer Prevention Research, a journal of the American Association for Cancer Research.
HPV vaccine hurdles
HPV vaccine concerns of side effects has remained a hurdle since Gardasil was first introduced in the United States.
Many experts even were critical about the push to get young girls vaccinated, suggesting more of a focus on nutrition, regular screening for cervical cancer and promoting natural immunity through nutrition and healthy lifestyles.
Some of the side effects reported in 2008 included blood clots, fainting and neurological disorders. Guillain-Barré Syndrome (GBS) has also been reported following Gardasil in addition to 20 deaths that autopsies (when available) showed were unrelated to the HPV vaccine, the Centers for Disease Control says.
A March, 2013 study published in the journal Pediatrics revealed 49.3 percent of parents surveyed feared HPV vaccine side effects, contributing to low rates of immunization.
As of July, 2008, the manufacturer of Gardasil, Merck and Co., had distributed over 16 million doses in the United States, according to the CDC who states: “As of June 30, 2008, there have been 9,749 VAERS reports of adverse events following Gardasil vaccination. Of these, 94% were classified as reports of non-serious events, and 6% as serious events.”
Non-serious events reports include fainting, soreness at the injection site, fever and headache.
Getting the vaccine is an individual choice that is recommended by the CDC, unlike Japan who has withdrawn recommendations for the vaccine specifically from concerns about side effects.
About cervical cancer
Cervical cancer is almost always caused by HPV that causes no symptoms and is extremely common. For most women, the infection will go away.
The risk of infection is higher for women who smoke, have had three or more children, multiple sexual partners or used birth control for 5-years or more.
The new finding suggests one dose of HPV vaccine could be enough to protect against cervical cancer but for now three-doses is still recommended until more studies are done to find out how much is really needed.
CDC.gov: Cervical cancer'
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