COVID-19 Vaccine Effectiveness: A New York State Dept. of Health Study


The New York State Department of Health announced the release of a new study. The study addresses one of the most critical questions regarding COVID-19 vaccines, are the vaccines effective, and to what extent? This study focuses on an important issue that to which extent the vaccine effectiveness is declining and whether these changes are due to waning immunity or the predominance of the Delta variant or any other factor.

The study focuses on the work of the Health Department’s first-in-the-nation vaccine effectiveness study, which was published in August by the Centers for Disease Control and Prevention. The study concluded that the declines in vaccine effectiveness can be primarily by the Delta variant. It can also depend on various other factors like immunological waning, or such as reduced use of masks.

“This latest study conducted by our renowned scientists here at DOH is the largest to examine in-depth changes in vaccine effectiveness over time broken down by all three COVID-19 vaccines types currently authorized for use in the United States,” Senior author and Health Commissioner Dr. Howard Zucker said. “It clearly demonstrates what we’ve been saying all along – getting a COVID-19 vaccine continues to be the best way out of this pandemic, and the best way for New Yorkers to prevent serious illness and hospitalization. We urge all New Yorkers to remain vigilant and get vaccinated against COVID-19 if you have not already done so.”

DOH scientists expanded upon their earlier analytic approach based on statewide linked immunization, laboratory testing, and hospitalization databases to calculate vaccine effectiveness over time. The new study focuses on nearly 9 million New Yorkers, who are 18 years of age and older. They have analyzed changes in vaccine effectiveness by age, vaccine product, and month of vaccination. The study witnessed vaccinated people from January through April 2021 and examined their levels of newly diagnosed infections and hospitalizations from May to August 2021, compared to people who never received a vaccine.

The analysis found the following:

Between the weeks of May 1 and August 28, decreases in vaccine effectiveness 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).


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