COVID-19 vaccines 66% effective against the Delta variant

Aug 25, 2021 – Vaccine efficacy against COVID-19 infection increased from around 91% to 66% once the Delta variant became the dominant strain in the United States, according to a new study released Tuesday by the CDC.

This decline is testament to the highly contagious nature of the Delta variant and emphasizes the importance of vaccination to prevent serious illness, hospitalizations and death, the study authors wrote.

“While we have seen a reduction in protection from COVID-19 vaccine against the Delta variant, it’s still a two-thirds reduction in risk, ”Ashley Fowlkes, ScD, lead author and epidemiologist for the CDC’s COVID-19 emergency response, told CNN.

The latest update is part of a study that tracks healthcare workers, first responders and other essential workers who are tested weekly in eight locations in six states. The weekly tests help researchers better track the rates of people who develop mild or no symptoms and may be less likely to get tested overall, CNN reported.

Of the 4,217 participations, 3,483 – or 83% – were vaccinated. About 65% received the Pfizer vaccine, 33% received the Moderna doses, and 2% received the Johnson & Johnson vaccine. Between December 2020 and April 2021, the vaccines were about 90% effective at preventing infections with and without symptoms.

Between April and August, the Delta variant became more dominant and the vaccine’s effectiveness began to decline, although there were still few infections. The researchers found 19 infections among 488 unvaccinated people, and about 95% had symptoms. They also found 24 infections among 2,352 fully vaccinated people, and 75% had symptoms. The study did not include details on the type of symptoms or their severity.

“It’s still a very potent vaccine,” Fowlkes told CNN. “But we are also considering continuing to use masks for a bit longer. “

The study team is planning future scans that compare different COVID-19 vaccines and the types of symptoms that vaccinated and unvaccinated people have, CNN reported.

Johnson & Johnson reported on Wednesday that a second dose of their vaccine increases levels of antibodies against the coronavirus. When participants received a booster shot at 6 months, their spike binding antibodies increased about nine times more than after the first dose, the company wrote. in a report.