The HPV Vaccine

by Natasha Kasbekar

What is HPV?

HPV is short for Human Papilloma Virus. This virus is very common, and is usually asymptomatic, which means people are not aware that they have it. It is acquired through sexual contact. A majority of sexually active adults will acquire HPV infection at some point in their lives. The CDC estimates that approximately 20 million Americans are currently infected. Adolescents and young adults make up about half the number of infections. Some infections will resolve on their own but some persist and can cause problems, the worst of which is cancer. There are over 40 types of HPV virus. Several of these are oncogenic, which means that they infect mucosal cells and cause cancer. These include cancers of the genital area in females and males as well as cancers of the mouth and throat. Every year about 12,000 women in the U.S. is diagnosed with cervical cancer. Cervical cancer causes about 4,000 deaths per year in the U.S.

 

What is the HPV vaccine?

The HPV vaccine is a cancer vaccine. Its main goal is to prevent cervical cancer. It does this by preventing infection with certain strains of the HPV virus. The HPV vaccine targets 4 strains of the virus, two of which are highly oncogenic (cancer-causing). When women have pap smear testing done, gynecologists look for changes in cervical cells (pre-cancerous lesions). The goal of the HPV vaccine is to intervene one step ahead and prevent the changes from occurring in the first place.  The HPV vaccine can also prevent genital warts, some types of oropharyngeal cancers, as well as some types of genital cancer in males.

The vaccine is made up of non-infectious HPV-like particles. The vaccine does not contain mercury or thimerosal. The vaccine is given as a three dose series at ages 11-12 years. The second dose is two months after the initial vaccine and the third is four months after that. The series does not have to start over if the boosters are given late. Catch-up immunization can be done through age 26 years. Studies have shown that the antibody response is more robust, with higher levels of antibodies achieved, when the vaccine series is given at ages 11-12 years compared to above age 16 years. Data so far has shown that high antibody levels are maintained for beyond seven years, so it does not currently appear that additional boosters beyond the three doses will be needed. It is also important to administer the full series well before any potential exposure to the virus. This is the same principle that guides timing of other routine childhood immunizations. Studies have shown that giving the vaccine at ages 11-12 years does not lead to an increase in early sexual activity.

 

Is the HPV vaccine effective?

The HPV vaccine has been proven to be effective in clinical trials. During trials to obtain FDA approval, it was shown that precancerous lesions caused by HPV types 16 and 18 (cervical intraepithelial neoplasia grade 2/3 or adenocarcinoma in situ) were reduced by 100%. Female genital warts were reduced by 97%. Genital warts in males were reduced 89%.

Since being licensed, the vaccine has continued to demonstrate dramatic benefits. In the U.S., there has been a 56% reduction in the prevalence of HPV strains 6, 11, 16, and 18 despite the fact that only 33% of girls received all three doses. A reduction of 77% in those strains of HPV was demonstrated in Australia where the three-dose immunization rate was 70%. Actual numbers for reduction in cancer rates will take longer to determine, due to the time between HPV infection and the development of cancer. However, the prevention of pre-cancerous lesions makes it clear that the vaccine is achieving the goal.

 

Is the HPV vaccine safe?

The HPV vaccine has undergone rigorous testing by medical and scientific experts to ensure its safety. Because of this extensive research, we can be confident that the HPV vaccine is very safe. Like most other vaccines, the most common adverse reaction is injection site soreness or redness. This is generally mild and resolves quickly. The most common safety concern is syncope (fainting). This can occur with any adolescent medical procedure or vaccine, and can be minimized by having the patient sit or even lie down for about fifteen minutes after the vaccine is given. No long term side effects have been reported. Most importantly, no serious safety concerns have been identified since the vaccine’s routine use. Through 2013 almost 60 million doses of the HPV vaccine had been given in the U.S.

 

Why should boys get the HPV vaccine?

Boys also can be infected with the HPV virus. In males, HPV can cause genital warts in addition to genital, anal, and oropharyngeal cancers which can be prevented by preventing the infection. Every year in the U.S., about 9,000 men are diagnosed with HPV-related cancers. In addition, vaccination of males will reduce the spread of the virus to females, decreasing the overall incidence of HPV and HPV-related diseases.

 

For more information about the HPV vaccine, check out the CDC website which contains links to useful information.

Posted in: Adolescent health, Infectious/Communicable Disease, Vaccines Tag(s): , , , , , , , , , .

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