ALBANY, NY – The New York State Department of Health recently announced the release of the largest comparative study of its kind on immunity to COVID-19 from vaccines and past infections, continuing its groundbreaking work on the effectiveness of vaccines.
The study, which also contains new data on reinfections, was conducted in collaboration with researchers from the California Department of Public Health and the Centers for Disease Control and Prevention (CDC), and published in the Morbidity and Mortality Weekly Report ( MMWR) from the CDC. He found that vaccination and previous infection provided protection against future infection and hospitalization.
Researchers found that from May to November 2021, COVID-19 cases and associated hospitalizations were significantly lower among those who had been vaccinated and/or survived a previous infection, compared to those who had not. been vaccinated and without previous infection. The study concluded that although after the appearance of the Delta variant, new infections and hospitalizations were lowest among people who had already been infected, especially those who had also been vaccinated.
The results show that vaccination remains the surest way to prevent future COVID-19 infections and serious consequences, including death. Since the start of the pandemic, more than 63,500 New Yorkers have died from COVID-19.
“This study led by our top scientists continues to underscore the importance of vaccination as an essential tool in the response to COVID-19,” said study co-author and NIHB Health Commissioner. State, Dr. Mary T. Bassett.
“Although the epidemiology of this virus may continue to change as new variants emerge, vaccination remains the surest way to prevent infection, hospitalization and death. We continue to urge all eligible New Yorkers to get vaccinated and boosted, wear a mask, and take all possible steps to protect yourself and your loved ones,” Bassett noted.
The study is based on more than 32 million adults who have had at least one COVD-19 test, grouped as follows:
• Group 1: unvaccinated with no previous laboratory-confirmed COVID-19 diagnosis;
• Group 2: vaccinated (14 days after the end of a primary COVID-19 vaccination series) without a previous diagnosis of COVID-19;
• Group 3: Unvaccinated who survived a previous diagnosis of COVID-19; and
• Group 4: vaccinated who survived a previous diagnosis of COVID-19.
During the study period from May 30 to November 20, 2021, new cases of COVID-19 in both states were highest among unvaccinated people with no previous diagnosis of COVID-19 compared to the other three groups. After the Delta variant became predominant in late June and July, case rates were lowest among vaccinated people with no previous COVID-19 diagnosis, and lowest among the two groups with a previous COVID-19 diagnosis.
For example, in New York State, during the week beginning October 3, unvaccinated people with no previous diagnosis of COVID-19 were 4.5 times more likely to test positive for COVID-19 than unvaccinated people. vaccinated people with no previous diagnosis of COVID-19 (Group 1 vs 2), 14.7 times more likely than unvaccinated people with a previous diagnosis (Group 1 vs 3) and 19.8 times more likely than vaccinated people with a previous diagnosis of COVID-19 (group 1 versus 4).
During the same period, compared to unvaccinated people without a prior diagnosis of COVID-19, the number and rates of hospitalizations in California followed a similar trend. For example, from October 3 to 16, hospitalization rates in unvaccinated people without a previous diagnosis of COVID-19 were 19.8 times higher than in vaccinated people without a previous diagnosis of COVID-19 (group 1 vs. 2 ), 55.3 times higher than in unvaccinated people with previous diagnosis of COVID-19 (group 1 vs. 3) and 57.5 times higher than in vaccinated people with previous diagnosis of COVID -19 (group 1 vs 4).
These results, in two large states that accounted for one in six deaths in the United States from COVID-19 through the end of November, suggest that vaccination protected against infection and related hospitalization, but also that surviving an infection anterior protected against reinfection and hospitalization. These results apply to the period before the emergence of the Omicron variant and the widespread use of booster doses.
Getting vaccinated and staying up to date with booster doses remains the most effective and only recommended way to build immunity against COVID-19. Being infected carries serious risks, including hospitalization and death, and makes it more likely that you will transmit COVID-19 to others, including those most at risk of hospitalization and death.
“This analysis represents another chapter in our ongoing studies of this virus and the most effective ways to protect against the disease. Our knowledge is evolving with the virus and together with our public health partners, we will continue to explore these issues to best inform and protect the public,” explained study lead author Dr. Eli Rosenberg of the Ministry. of Health.
This work includes an unprecedented examination of reinfections, which are new infections among people who have already been diagnosed with COVID-19. To provide the public with ongoing information about reinfections, the Department also announced the launch of a new dashboard containing data on COVID-19 reinfection in New York State. The Department also launched a pioneering breakthrough data dashboard after its Vaccine Effectiveness Study was released last year.
Data from the new Reinfection Dashboard expands on the findings of the new study to illustrate that while reinfections have always been rare, the number increased in December 2021 when the Omicron variant emerged in New York State. This information will continue to be important in understanding the extent of infection in New York State during the current wave, complementing the other dashboards available on the Department’s webpage.
Updates to this Reinfection Dashboard will be posted weekly.