Efforts to increase uptake of the human papillomavirus (HPV) vaccine appears to be paying off, according to a new study. The report in the journal Pediatrics notes that in a U.S. community more than a decade after 4-valent HPV vaccine introduction and at a point after 9-valent vaccine introduction, evidence of vaccine effectiveness and herd protection was documented.
University of Cincinnati–led researchers point out that clinical trials of the 4-valent HPV vaccine demonstrate high efficacy, cautioning that surveillance studies also are critical to examine the long-term effect of vaccine introduction on HPV prevalence in communities.
The researchers sought to determine, during the 11 years after vaccine introduction, the prevalence of vaccine-type HPV in adolescent and young adult women who were vaccinated (to assess vaccine effectiveness) and vaccine-type HPV in women who were unvaccinated (to assess herd protection).
To determine prevalence, the study team recruited women aged 13 to 26 years from hospital-based and community health clinics for four surveillance studies from 2006 to 2017.
Results indicate that vaccination rates increased from 0% to 84.3%, with 97% of study participants who were immunized receiving the 4-valent vaccine.
Among the vaccinated group, detection of 4-valent vaccine–type HPV showed a decrease from 35% to 6.7% (80.9% decline; odds ratio 0.13, 95% confidence interval 0.08-0.22). At the same time, women who had not been vaccinated also showed a significant drop in 4-valent vaccine–type HPV cases; detection showed a decrease from 32.4% to 19.4% (40% decline; odds ratio 0.50, 95% confidence interval 0.26-0.97). Based on that, researchers estimated vaccine effectiveness at 90.6% in wave 3 and 80.1% in wave 4.
“In this study in which trends in HPV in a U.S .community >10 years after 4-valent HPV vaccine introduction and after 9-valent vaccine introduction were examined, we found evidence of vaccine effectiveness and herd protection,” the study authors conclude. “Further research is needed to examine trends in 9-valent vaccine–type HPV after higher rates of vaccination are achieved.”
The researchers emphasize that the significant decreases in 4-valent vaccine–type HPV, 9-valent vaccine–type HPV, and the five additional HPV types included only in 9-valent vaccine were detected among women who were vaccinated. That suggests “4-valent vaccine effectiveness in a real-world setting and possible cross-protection against genetically related HPV types,” they write. “The significant decrease in 4-valent HPV types among women who were unvaccinated suggests herd protection. Although these findings are important for clinical care and public health policy, continued surveillance will be important to assess for waning vaccine effectiveness, herd protection, and the impact of 9-valent vaccine introduction.”
« Click here to return to Vaccine Update.