Trials: COVID vaccines 90% effective against Delta infection, death
"A pair of new real-world COVID-19 vaccine studies show good protection against the Delta (B1617.2) variant, one from Scotland finding higher than 90% effectiveness in preventing death in adults and the other showing 93% efficacy against symptomatic infection in Israeli adolescents after the second dose."
Both studies were published as letters today in the
New England Journal of Medicine (
NEJM).
Vaccines 90% effective against adult deaths
In the most recent results of the UK observational
study, a team led by a University of Edinburgh researcher estimated the odds of COVID-19 death among 114,706 vaccinated and unvaccinated Scottish adults (plus teens aged 16 and 17) who tested positive for COVID-19 from Apr 1 to Aug 16, 2021, and were followed up until Sep 27.
Vaccinees had received one or two doses of the Pfizer/BioNTech or AstraZeneca/Oxford COVID-19 vaccines. Relative to the vaccinated, unvaccinated adults tended to be much younger, have fewer chronic conditions, have lower socioeconomic status, and be men. Whole-genome sequencing showed that nearly all infections were caused by Delta.
Of 201 total COVID-19 deaths, none occurred among the 7,180 fully vaccinated participants 16 to 39 years old, compared with 17 among the 35,449 unvaccinated participants in that age-group (0.05%). Of participants aged 40 to 59, 33 deaths occurred among the 4,803 unvaccinated participants (0.69%), versus 18 among 12,905 in the fully vaccinated group (0.14%) (16 with AstraZeneca, 2 with Pfizer).
Overall effectiveness against death from Delta infections at least 14 days after the second vaccine dose was 90% (95% confidence interval [CI], 83% to 94%) for Pfizer and 91% (95% CI, 86% to 94%) for AstraZeneca.
Among 40- to 59-year-olds, the vaccines were 88% effective (95% CI, 76% to 93%) against death for AstraZeneca and 95% (95% CI, 79% to 99%) for Pfizer. Overall effectiveness against death was 90% (95% CI, 84% to 94%) with AstraZeneca and 87% (95% CI, 77% to 93%) with Pfizer among those 60 years and older.
First author Aziz Sheikh, MD, said in a University of Edinburgh
news release that although the research must be repeated in other settings with longer follow-up time, the results are encouraging.
"With the Delta variant now the dominant strain in many places worldwide and posing a higher risk of hospitalization than previous variants seen in the UK, it is reassuring to see that vaccination offers such high protection from death very shortly after the second dose," he said.
"If you still have not taken up your offer to be vaccinated, I would encourage you to do so based on the clear benefits it offers."
Trials: COVID vaccines 90% effective against Delta infection, death