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Why comparing Covid-19 vaccine efficacy numbers can be misleading
The best Covid-19 vaccine for you is most likely still the first one you can get.
www.vox.com
“Timing is critical too. The Moderna and Pfizer/BioNTech studies finished enrolling participants in their phase 3 trials in October and reported their results in late November. The Johnson & Johnson phase 3 trial only finished enrolling participants in December 2020 and reported their results in January.
That means the Johnson & Johnson vaccine was tested during one of the most severe stages of the pandemic, when transmission, cases, and hospitalizations were at their worst in many places around the world, including the US. The trial also captured efficacy against the new variants of SARS-CoV-2 (the virus that causes Covid-19) which began circulating at this point in some parts of the world. Several of these variants have shown themselves to be more contagious, deadlier, and more likely to evade protection from vaccines and prior immunity.”
But when Johnson & Johnson filed for an emergency use authorization from the Food and Drug Administration for its Covid-19 vaccine in early February, it reported that its overall efficacy in preventing Covid-19 cases that produced symptoms was 66.1 percent. The Moderna vaccine and the Pfizer/BioNTech vaccines reported efficacy levels around 95 percent.
In addition, health officials have been emphasizing that the most important numbers — how well the vaccines prevent hospitalizations and deaths — are consistent across the board and are arguably more comparable. Even after these vaccines have begun distribution, researchers are finding that Covid-19 vaccines are doing a remarkable job of keeping people alive.
That’s why the recommendation remains that the best Covid-19 vaccine for the vast majority of people is the first one they can get. “That’s how I think of these vaccines, as basically interchangeable,” said Adalja.
