STATEN ISLAND, N.Y. — A New York State Department of Health (DOH) study released Monday found recent modest dips in coronavirus (COVID-19) vaccine efficacy were more likely the cause of the virulent delta variant and other factors like reduced use of masks.
The study, published on the preprint server medRxiv and dubbed the largest United States study by vaccine type and timing of vaccination, included more than 8.8 million New York adults through the use of statewide testing, hospital and vaccine registry databases to compare vaccine effectiveness over time.
Researchers tracked people vaccinated in January through April of this year and examined levels of new infections and hospitalizations from May to August, 2021, and compared those results to people who never received a vaccine.
The findings showed vaccines remained highly effective against the worst COVID-19 outcomes, specifically hospitalizations, with “modest declines limited to Pfizer-BioNTech and Moderna recipients 65 years of age and older.”
Those results, the state DOH added, supported administering booster doses to older individuals.
“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,” said senior author and outgoing Health Commissioner Dr. Howard Zucker.
“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,” added Zucker. “We urge all New Yorkers to remain vigilant and get vaccinated against COVID-19 if you have not already done so.”
Statewide, 72.2% of all New Yorkers have received at least one dose of a COVID-19 vaccine, and 64.5% of the state is considered fully vaccinated. More than 85% of all New York adults are partially vaccinated while 76.3% have either received one dose of the Johnson & Johnson vaccine or two doses of the Moderna or Pfizer vaccines.
The study found Pfizer’s vaccine effectiveness dipped the most significantly against laboratory-confirmed infections, followed by Moderna and Johnson & Johnson’s vaccines.
Those decreases in effectiveness happened simultaneously across age groups and other demographics like when an individual was vaccinated during weeks when the delta variant rapidly increased.
When the delta variant passed 85% prevalence in New York, those changes in vaccine effectiveness plateaued, the study’s authors said, with more recently vaccinated people seeing higher levels of protection.
However, continued declines in effectiveness were seen for people 65-years and older.
“These results suggest that declines in VE [vaccine effectiveness] 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,” the DOH said.
The study found that vaccines remained highly effective against hospitalizations, with a mild decline seen in Pfizer and Moderna recipients over the age of 65.
“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,” said lead study author Dr. Eli Rosenberg.
“We saw limited evidence of decline in effectiveness against severe disease for people ages 18 to 64 years old,” said Rosenberg. “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.”
Last month, the FDA authorized a booster dose of the Pfizer vaccine. Moderna and Johnson & Johnson have submitted their applications seeking authorization for a booster shot of its vaccine.
So far, Pfizer’s booster doses have been granted for people ages 65 and older, those with certain underlying conditions and those who are frequently exposed to the virus.