COVID-19 Vaccines Prove Potency in Real-World Studies
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A clinical trial is the gold standard for determining the safety and efficacy of drugs and vaccines, but it’s not quite the same as the real world. As the vaccines against COVID-19 are being rolled out worldwide, numerous studies are being conducted to evaluate how the vaccines do under less controlled situations. Here’s a look.
Pfizer-BioNTech Vaccine in Israel
A real-world study of the Pfizer-BioNTech vaccine in more than half a million people confirmed the vaccine’s effectiveness at preventing serious illness or death—even after only a single dose. The vaccine is designed for two doses about three weeks apart, but the U.K., for instance, has delayed the second dose to about 12 weeks to make more doses available.
In the study, which was conducted by researchers from the Clalit Research Institute and Ben-Gurion University of the Negev in Israel, with Harvard University in the U.S., found the vaccine was 92% effective at preventing disease after two shots and 62% after a single shot. It appeared 72% effective at preventing death two to three weeks after the first dose, which seems to improve over time. It was as effective in people over the age of 70 as it was in younger people.
“This is immensely reassuring … better than I would have guessed,” said Gregory Poland, with the Mayo Clinic.
This is a very similar result to the 95% effectiveness after two doses observed in the clinical trials the U.S. Food and Drug Administration (FDA) used to grant emergency use authorization (EUA).
Senior study author Ran Balicer told Reuters, “We were surprised because we expected that in the real-world setting, where cold chain is not maintained perfectly and the population is older and sicker, that you will not get as good results as you got in the controlled clinical trials. But we did and the vaccine worked as well in the real world.”
The study also suggested the Pfizer-BioNTech vaccine was effective against the U.K. variant. The research didn’t offer a specific efficacy level, but at the time of the study in Israel, the U.K. variant was the dominant strain. No data was available from this study on how the Pfizer-BioNTech vaccine works against the South African variant.
Moderna and Pfizer-BioNTech
Researchers with Nference in Cambridge, Massachusetts and the Mayo Clinic in Rochester, Minnesota, conducted a real-world study on both the Moderna and Pfizer-BioNTech vaccines. The data showed both were effective at preventing infection and decreasing the severity of COVID-19. The data also demonstrated the shots effectively protected people who were at highest risk of COVID-19 infections and who were likely to experience the most severe disease.
“Building upon the previous randomized trials of these vaccines, this study demonstrates their real-world effectiveness in reducing the rates of SARS-CoV-2 infection and COVID-19 severity among individuals at the highest risk for infection,” the researchers wrote.
The study was published on the preprint server medRxiv, and has not been peer-reviewed.
It evaluated 31,069 people who received at least one dose of either vaccine with 31,069 people who did not receive vaccines. They found that two doses of vaccines was 88.7% effective in preventing COVID-19 infection with onset at least 36 days after the first dose. And people who were vaccinated who did get infected, had significantly lower 14-day hospital admission rate than unvaccinated COVID-19 patients, 3.7% compared to 9.2%.
The authors point out that, “One challenge inherent to such real-world analyses is the lack of a built-in placebo arm, which is essential to establish the expected infection rate during the study period and thereby to assess vaccine efficacy.”
Which is why they pulled together a cohort of 31,069 people who had not received a vaccine by the end of the study period. The 88.7% efficacy rate is very good, although less than the approximately 95% seen in the controlled clinical trials. However, one of the key elements is that none of the people who were vaccinated who developed COVID-19 died of the disease.
“Our data demonstrated a strong real-world effect of COVID-19 vaccination on par with the results reported in each randomized trial,” they wrote. “We emphasize that COVID-19 vaccines should be administered as broadly and rapidly as possible to the public and that the real-world efficacy of these vaccines should be continuously monitored as we move beyond Phase Ia of the distribution process.”