Date of Award

January 2023

Document Type


Degree Name

Master of Public Health (MPH)


School of Public Health

First Advisor

Linda Niccolai


Human papillomavirus (HPV) vaccination is currently recommended for ages 11-12 in the United States. Vaccination at later ages may diminish vaccine effectiveness (VE) against HPV-associated diseases and infections. There is limited data on the extent to which VE for HPV vaccination differs by age at vaccination in real-world populations.

Surveillance data from the Connecticut HPV Vaccine Impact Monitoring Project (HPV- IMPACT) from women in New Haven County was used. Archived tissue from cervical intraepithelial neoplasia grades 2 and 3 and adenocarcinoma in situ (collectively called CIN2+) lesions were tested for HPV type. Medical records were reviewed to ascertain HPV vaccination history. Women who tested positive for HPV types 16 and 18 (HPV-16/18) were classified as cases, and women who tested negative were classified as controls. VE was estimated as 1 minus the adjusted odds ratio (aOR) from a logistic regression model that compared vaccination status and age at vaccination for cases and controls while adjusting for confounding.

Of 5,947 women diagnosed with CIN2+ between 2008 and 2019, 1,753 women with known vaccine status, age at vaccination, and typed biopsy specimens were analyzed. In the study sample, 8.9% of women were vaccinated at ≤18 years of age, 35.6% were vaccinated at >18 years of age, and 64.4% were unvaccinated. aORs for vaccination at ≤18 and >18 were 0.21 (95% confidence interval (CI): 0.13, 0.35) and 0.64 (95% CI: 0.47, 0.87), yielding VE estimates of 79% (95% CI: 65%, 87%) and 36% (95% CI: 13%, 53%) respectively.

We found higher VE against HPV-16/18 CIN2+ in women vaccinated ≤18 years of age compared to those vaccinated >18 years of age, highlighting the importance of early vaccination. Continued surveillance will allow for greater sample sizes in future research evaluating VE in more refined age groups, which will provide further support to current recommendations for HPV vaccination at earlier ages in the United States.


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