WHO reports that all 3 vaccines—bivalent, quadrivalent, and nonavalent—are “comparable” when it comes to “immunogenicity, efficacy, and effectiveness” in cervical cancer prevention. When it comes to choosing which vaccine to use, WHO suggests taking “locally relevant data” into consideration as well as factors such as “the scale of the prevailing HPV-associated public health problem” and the “population for which the vaccine has been approved.” The cost and nature of the vaccination program should also be considered.
A 2-dose schedule—with 6 months in between doses—is recommended for those who are receiving their first dose of the vaccine before 15 years of age. However, a 2-dose schedule is also acceptable for those who are over 15 years of age at the time of the second dose. WHO recommends a 3-dose schedule—to be taken at 0, 1, 2, 6 months—for all individuals over 15 years of age receiving their first dose; this dosing schedule is also recommended for those who are under the age of 15, who are HIV-infected or are otherwise immunocompromised.
For the most part, adverse events associated with HPV vaccination are “non-serious and of a short duration.” HPV vaccination is safe in those who are immunocompromised or HIV-infected, authors write. WHO recommends that pregnant women not be vaccinated, as there is limited data available regarding how safe immunization is in this population.
WHO recommends “monitoring prevalence of infection by HPV type among sexually active young women,” as they feel that it could “provide an early indication of vaccine effectiveness.” However, the authors note that doing this effectively would require “considerable commitment of resources for at least 5-10 years,” and thus, might not be an appropriate strategy for all countries. They do recommend that healthcare officials from all countries work on reporting to comprehensive cancer registries, as these registries “are needed to measure the impact of HPV vaccine programs and of cervical cancer screening.”
Lastly, WHO is calling for more research regarding HPV vaccination. The authors write, “Further research is needed to generate data on the longer-term clinical effectiveness and duration of protection, particularly for the nonavalent HPV vaccine, after 2-dose and 3-dose schedules.” They also call for more multicenter studies (on healthy young women as well as those who are infected with HIV, who are malnourished, or are exposed to malaria) within low-income countries to gage how vaccination impacts these populations.
“Further evidence is required on the effectiveness and cost-effectiveness of a 1-dose schedule, and on the immunogenicity and safety of administering HPV vaccine to children less than 9 years of age,” they added.
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