Covid-19 Vaccine Effectiveness in New York State

Area of Science:

• Immunology
• Public Health
• Epidemiology

Background:

• Limited US data exists on the real-world effectiveness of authorized COVID-19 vaccines.
• The impact of waning immunity versus the SARS-CoV-2 delta variant on vaccine effectiveness is unclear.

Purpose of the Study:

• To assess the effectiveness of BNT162b2, mRNA-1273, and Ad26.COV2.S vaccines against COVID-19 and hospitalization.
• To evaluate vaccine effectiveness trends in New York State adults from May to September 2021.

Main Methods:

• Utilized linked statewide data for over 8.6 million adults, including vaccination, testing, and hospitalization records.
• Compared vaccinated cohorts to age-specific unvaccinated cohorts to determine vaccine effectiveness.
• Analyzed effectiveness against laboratory-confirmed COVID-19 and COVID-19-related hospitalizations.

Main Results:

• Initial vaccine effectiveness against COVID-19 was high for all three vaccines (BNT162b2: 91.3%, mRNA-1273: 96.9%, Ad26.COV2.S: 86.6%).
• Effectiveness against COVID-19 declined significantly as the delta variant became predominant, reaching a nadir of 73.5% around July 10.
• Effectiveness against hospitalization remained high (>86%) for younger adults (18-64) but showed modest declines in older adults (≥65) vaccinated with BNT162b2 or mRNA-1273.

Conclusions:

• COVID-19 vaccine effectiveness against infection decreased with the rise of the delta variant.
• Protection against COVID-19 hospitalization remained robust, with only minor reductions observed in specific older adult groups.
• The Ad26.COV2.S vaccine demonstrated lower overall effectiveness compared to mRNA vaccines.