NYSDOH says new study shows effectiveness of COVID-19 vaccines

covid vaccine
Posted at 1:24 PM, Oct 11, 2021

NEW YORK (WKBW) — The New York State Department of Health (NYSDOH) released a new study Monday that it says shows the continued effectiveness of COVID-19 vaccines.

The study, which can be found here, expands on its vaccine effectiveness study that was published by the CDC in August.

Statewide linked immunization, laboratory testing and hospitalization databases were used to determine vaccine-effectiveness (VE) over time of nearly nine million New Yorkers 18 and older.

According to a release from NYSDOH, the study and analysis found the following:


  • Between the weeks of May 1 and August 28, decreases in VE against laboratory-confirmed infections were greatest for Pfizer-BioNTech (-24.6% for 18-49, -19.1% for 50-64 and-14.1% for 65 and older), and similar for Moderna (-18.0% for 18-49, -11.6% for 50-64 and - 9.0% for 65 and older) and Janssen (-19.2% for 18-49, -10.8 for 50-64 and -10.9% for 65 years of age and older).


  • The declines in VE for laboratory-confirmed infections occurred simultaneously across groups defined by age, product and month of vaccination, during the weeks when Delta variant rapidly increased, with the largest declines seen for Pfizer-BioNTech recipients. 
  • After the Delta variant exceeded 85% prevalence, these changes in VE plateaued, with more recently vaccinated people at higher protection levels in some groups. Modest continued declines in VE were seen for people 65 years of age and older.  
  • These results suggest that declines in VE for infections occurred during the study time period but may have been driven primarily by factors other than immunological waning, such as the Delta variant or changes in COVID-19 prevention behaviors.


  • Vaccine effectiveness for hospitalization for adults 18-64 years was more than 86% across cohorts, with no trend over time. Among people aged 65 years or older, VE declined from May to August for Pfizer-BioNTech (95.0% to 89.2%) and Moderna (97.2% to 94.1%). VE was lower for Janssen, with no time trend, ranging 85.5%- 82.8%.
  • The study concluded that VE for COVID-19 hospitalizations remained high, with modest declines limited to Pfizer-BioNTech and Moderna recipients 65 years of age and older.  

Lead study author Dr. Eli Rosenberg of the Department of Health released the following statement:

The findings of our study support the need for boosters in older people in particular, and we encourage them to seek out a booster shot from their health care provider, pharmacy or mass vaccination site. We saw limited evidence of decline in effectiveness against severe disease for people ages 18 to 64 years old. While we did observe early declines in effectiveness against infections for this age group, this appears to have leveled off when the Delta variant became the predominant strain in New York. Together, this suggests that ongoing waning protection may be less of a current concern for adults younger than 65 years.
- Dr. Eli Rosenberg