People who were vaccinated against COVID-19 were less likely to die from other causes than similar unvaccinated people, according to a new study published in the Morbidity and Mortality Weekly Report from the U.S. Centers for Disease Control and Prevention (CDC).
Most of the discussion of COVID-19 vaccines in health media concerns their efficacy at preventing COVID-19 and its worst outcomes, such as hospitalization, admission to the intensive care unit (ICU), and death. By these measures, the vaccines are highly effective, especially with recommended “booster” doses of the two most commonly received vaccines in the United States. For example, a recent trial showed that in people ages 16 and older who received a third dose of the Pfizer vaccine, the vaccine’s efficacy rate against COVID-19 infection was higher than 95%. But vaccines can also have positive “downstream” effects that are unrelated to the disease they were designed to protect against — something that has long been known to happen with other vaccines, including annual flu shots. It can be difficult, though, to separate the actual beneficial effects of vaccines from the effects of other healthier behaviors that may be seen in people who receive them.
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For the latest study, researchers compared the risk of death from causes other than COVID-19 in people who got vaccinated against the viral infection, and in a sample of people who didn’t get vaccinated. This sample of unvaccinated people consisted entirely of people who had gotten at least one flu shot in the last two years, “to ensure comparable health care-seeking behavior among persons who received a COVID-19 vaccine and those who did not,” according to the researchers. Death rates in each study group were also adjusted for age, sex, race and ethnicity, and study site. The study’s participants were about 11 million people, ages 12 and older, who received health care at one of seven Vaccine Safety datalink (VSD) sites between December 2020 and July 2021. These health care providers reported deaths from all causes, as well as lots of other data, as part of their VSD participation — the purpose of which is to support studies like this one, looking at the safety of vaccines.
COVID-19 vaccination linked to reduced death risk from other causes
The study participants included about 6.4 million people who had received a COVID-19 vaccine by the end of May 2021, and about 4.6 million people who had not. The researchers found different death risks associated with each of the three approved COVID-19 vaccines in the United States. Compared with people who didn’t receive a COVID-19 vaccine, those who received the Pfizer-BioNTech vaccine were 59% less likely to die from causes other than COVID-19 after the first dose, and 66% less likely after the second dose. Those who received the Moderna vaccine were 66% less likely to die from causes other than COVID-19 after the first dose, and 69% less likely after the second dose. Those who received the Janssen (Johnson & Johnson) vaccine were 46% less likely to die from causes other than COVID-19 following the single dose of the vaccine.
Since the purpose of this study was to confirm that COVID-19 vaccines didn’t increase the risk for death, that’s exactly what the researchers concluded. But the results, of course, show something more — that to varying degrees, people who received the vaccines were less likely to die of causes other than COVID-19. “The lower mortality risk after COVID-19 vaccination suggests substantial healthy vaccinee effects (i.e., vaccinated persons tend to be healthier than unvaccinated persons) which will be explored in future analyses,” the researchers wrote. But it’s possible that this “healthy vaccinee effect” isn’t enough to explain the differences in death risk, especially since the risk for death went down after the second dose of the two-dose vaccines. It’s possible that in this study, getting a COVID-19 vaccine actually reduced the likelihood of dying from other causes. More research is needed to find out whether COVID-19 vaccines actually do have this effect, and if so, to explain what happens in the body to reduce the risk of death from causes other than the viral infection.
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