Randomized controlled trials show all-cause mortality reduction from the COVID adenovirus-vector vaccines (RR=0.37, 95 percent CI: 0.19-0.70) but not from the mRNA vaccines (RR=1.03, 95 percent CI 0.63-1.71).
That’s the verdict from a new Danish study by Dr. Christine Benn and colleagues. Have people been given vaccines that don’t work (Pfizer/Moderna) instead of vaccines that do work (AstraZeneca/Johnson & Johnson)? Let’s put this study into context and then delve into the numbers.
In medicine, the gold standard for evidence is randomized controlled trials (RCT), as they avoid study bias for or against the vaccine. Moreover, the key outcome is death. Do these vaccines save lives? Hence, the Danish study answers the right question with the right data.
It is the first study to do so.
When the Pfizer and Moderna mRNA vaccines were approved by the U.S. Food and Drug Administration (FDA), that decision was based on RCTs. The RCTs submitted to the FDA showed that the vaccines reduce symptomatic COVID infections. By recruiting mostly younger and middle-aged adults, who are unlikely to die from COVID no matter what, the studies were not designed to determine whether the vaccines also reduce mortality.
That was assumed as a corollary, although it may or may not be true. Neither were the RCTs designed to determine whether the vaccines reduce transmission, but that’s a different story for another time.
The vaccines were developed for COVID, but to properly evaluate a vaccine, we must look at non-COVID deaths as well. Are there unintended adverse reactions leading to death? We don’t want a vaccine that saves the lives of some people but kills an equal number of other people. There may also be unintended benefits, such as incidental protection against other infections. For a fair comparison, that should also be part of the equation.
While each individual RCT was unable to determine whether the COVID vaccine reduced mortality, the RCTs recorded all deaths, and to increase sample size, the Danish study pooled multiple RCTs. There are two different types of COVID vaccines: adenovirus-vector vaccines (AstraZeneca, Johnson & Johnson, Sputnik) and mRNA vaccines (Pfizer and Moderna), and they did one pooled analysis for each type. Here are the results:
