Vaccine effectiveness against COVID-19 related hospital admission in the Netherlands by medical risk condition: A test-negative case-control study.

INTRODUCTION: Vaccination remains crucial in reducing COVID-19 hospitalizations and mitigating the strain on healthcare systems. We conducted a multicenter study to assess vaccine effectiveness (VE) of primary and booster vaccination against hospitalization and to identify subgroups with reduced VE. METHODS: From March to July 2021 and October 2021 to January 2022, a test-negative case-control study was conducted in nine Dutch hospitals. The study included adults eligible for COVID-19 vaccination who were hospitalized with respiratory symptoms. Cases tested positive for SARS-CoV-2 within 14 days prior to or 48 h after admission, while controls tested negative. Logistic regression was used to calculate VE, adjusting for calendar week, sex, age, nursing home residency and comorbidity. We explored COVID-19 case characteristics and whether there are subgroups with less effective protection by vaccination against COVID-19 hospitalization. RESULTS: Between October 2021 to January 2022, when the Delta variant was dominant, 335 cases and 277 controls were included. VE of primary and booster vaccination was 78 % (95 % CI: 65-86), and 89 % (95 % CI: 69-96), respectively. Using data from both study periods, including 700 cases and 511 controls, VE of primary vaccination was significantly reduced in those aged 60+ and patients with malignancy, chronic cardiac disease or an immunocompromising condition. CONCLUSION: Although VE against hospitalization was 78% and increased to 89% after boosting during the Delta-dominant study period, VE was lower in certain high risk groups, for which indirect protection or other protective measures might be of added importance.

Incidence and Types of Human Papillomavirus Infections in Adolescent Girls and Young Women Immunized With the Human Papillomavirus Vaccine.

Importance: Rates of human papillomavirus (HPV) infection have decreased since the introduction of HPV vaccines in populations with high vaccine uptake. Data are limited for adolescent and young adult populations in US metropolitan centers. Objective: To determine HPV infection rates in adolescent girls and young women aged 13 to 21 years in New York City following HPV vaccination. Design, Setting, and Participants: This cohort study of type-specific cervical HPV detection was conducted at a large adolescent-specific integrated health center in New York City between October 2007 and September 2019. Participants included an open cohort of adolescent girls and young adult women who received the HPV vaccine (Gardasil; Merck & Co) over a 12-year period following HPV vaccination introduction. Data analysis was concluded September 2019. Exposures: Calendar date and time since receipt of first vaccine dose. Main Outcomes and Measures: Temporal associations in age-adjusted postvaccine HPV rates. Results: A total of 1453 participants, with a mean (SD) age at baseline of 18.2 (1.4) years, were included in the cohort (African American with no Hispanic ethnicity, 515 [35.4%] participants; African American with Hispanic ethnicity, 218 [15.0%] participants; Hispanic with no reported race, 637 [43.8%] participants). Approximately half (694 [47.8%] participants) were vaccinated prior to coitarche. Age-adjusted detection rates for quadrivalent vaccine types (HPV-6, HPV-11, HPV-16, and HPV-18) and related types (HPV-31, and HPV-45) decreased year over year, with the largest effect sizes observed among individuals who had been vaccinated before coitarche (adjusted odds ratio [aOR], 0.81; 95% CI, 0.67-0.98). By contrast, detection was higher year over year for nonvaccine high-risk cervical HPV types (aOR, 1.08; 95% CI, 1.04-1.13) and anal HPV types (aOR, 1.11; 95% CI, 1.05-1.17). The largest effect sizes were observed with nonvaccine types HPV-56 and HPV-68. Conclusions and Relevance: Whereas lower detection rates of vaccine-related HPV types were observed since introduction of vaccines in female youth in New York City, rates of some nonvaccine high-risk HPV types were higher. Continued monitoring of high-risk HPV prevalence is warranted.