ABSTRACT
The human papillomavirus (HPV) vaccine has been proven effective in the prevention of infection with high-risk HPV types, which can lead to the development of six HPV-related cancers. Puerto Rico (PR) adopted a mandatory HPV vaccination school-entry policy that took effect in August 2018. While school-entry requirements are generally accepted as an effective approach for increasing vaccination rates, there are few studies that have documented their impact on improving HPV vaccination rates. The objective of this study was to evaluate the impact of the HPV school-entry policy in PR on HPV vaccine coverage. We used a pre-post natural experiment. The study population included adolescents registered in the PR Immunization Registry during 2008-2019. We calculated HPV vaccine initiation and up-to-date (UTD) vaccine coverage rates. We estimated age-standardized rates (ASR) and standardized rate ratio with 95%CI. Vaccine data corresponding to a total of 495,327 adolescents were included for analysis; 50.9% were male and 49.1% were females. After policy implementation, a marked increase in raw HPV vaccine initiation among 11- to 12-year-old adolescents was observed across years 2017 (a pre-policy year), 2018, and 2019 (58.3%, 76.3%, and 89.8%, respectively). UTD coverage also showed a moderate increase after policy implementation among 11- to 12-year-old adolescents. The gap between sexes in vaccine initiation and UTD coverage narrowed over time; the ASRs in 2019 showed an increase of 19% in initiation and 7% increase in UTD relative to 2017 for males and females combined (both significant at p<0.05). This study demonstrated evidence of improvement in HPV vaccination rates following implementation of the school-entry policy and a narrowed sex gap in vaccine rates over time in PR. Future analyses should assess how the policy continues to affect vaccine coverage in subsequent years and how the COVID-19 pandemic has impacted HPV vaccination uptake.
ABSTRACT
In September 2017, Hurricane Maria devastated the Caribbean region, among them the US territory of Puerto Rico (PR). Vaccination distribution and uptake suffered from the impact. This study evaluated the trends in monthly vaccination initiation rates for human papilloma virus (HPV), Tdap and meningococcal conjugate (MenACWY) adolescent vaccines from 2015 to 2019, during which it was possible to observe and analyze the impact of Hurricane Maria on vaccine initiation. Monthly initiation rates were estimated. Age-standardized initiation rate ratio (SRR) and 95% CI were estimated. The analysis included 85,340 adolescents; 52.3% were male, and 47.7% were females. September 2017 showed HPV vaccine initiation had the lower rates of all the studied vaccines, with a rate of 75% after the disaster (from a rate of almost 90% in July 2017). Tdap and MenACWY vaccines rates remained above 90% in the same period. The SRR of HPV vaccine for September and October 2017 showed an estimated reduction of 5% and 8% in vaccine initiation rates, respectively for each month, when 2016 was the reference year (p > .05). The SRR of Tdap and MenACWY vaccines for November 2017 showed significant reductions when 2015 and 2016 were reference years (p < .05). HPV vaccine initiation rate was the most severely affected by the Hurricane Maria. Post-natural disaster protocols should strengthen existing programs for facilitate immunization access.