Varicella vaccine success story. Varicella vaccine was approved in the 1990s, but both physicians and the public were slow to accept it, in part because it was relatively expensive for physicians to buy, and insurance companies were slow to pay for vaccination. What brought about widespread adoption of varicella vaccination was education on the dangers of chicken pox, directed to clinicians, patients, and government officials. This led to appreciation of the benefits of vaccination. As a result, states changed their school entry requirements, and today, almost all children receive the varicella vaccine.
The unknowns
It is important to recognize that with all new vaccines there are unknowns when they are first introduced.
What will the ACIP recommend?
One of the biggest concerns about the HPV vaccines is that we do not yet know who the ACIP will recommend for vaccination. In the clinical trials, the HPV vaccine did not appear effective in women already exposed to HPV. Since the cumulative incidence of HPV infection in young women is approximately 40% within 2 years of initiating intercourse, we will need to target adolescents prior to onset of sexual activity.3 In the US, 7.4% of adolescents report having begun having sexual intercourse by 13 years of age, and about one third by the ninth grade.4 Therefore the most likely primary target population will be young girls 11 to 12 years of age. It is also likely that there will be a recommendation for “catch-up” vaccination of older girls and young women.
What is the duration of protection afforded by HPV vaccination?
We know that the vaccine appears to provide protection for at least 4 years, but if we vaccinate 11- to 12-year-old girls, will they require a booster later in life?5
How will HPV vaccination affect cervical screening?
Once vaccination is widespread, a significant reduction in CIN 2,3 will occur, necessitating changes in the age to start screening and screening frequency. However, it is unclear what percentage of the population will need to be vaccinated before we change screening policy.
Will HPV vaccine be efficacious in women over the age of 26 years?
Vaccine trials are currently underway in older women, but until these trials are completed, all we can tell our older, sexually active patients is that we simply don’t know if the vaccine will benefit them.
Will parents, adolescents, and the public at large accept the vaccine?
As with all issues relating to sexual behavior, it is likely that opinions will differ as to the acceptability of vaccinating young adolescents against a sexually transmitted disease.