According to preliminary results published on the medRxiv platform, people that were infected with Covid-19 and recovered are better protected against the Delta variant than those vaccinated with the Pfizer-BioNTech’s vaccine.
The study, in which 779,000 people in Israel participated, is the largest study to date comparing natural immunity and immunity through vaccination. It showed that patients vaccinated with two doses of Pfizer’s vaccine (the only vaccine used in Israel) are 13 times more likely to be infected with the Delta variant than people infected with the virus in the January or February 2021 waves. The risk is still 5.96 times higher compared to people affected by the 2020 waves, where other variants circulated, and 7.13 times higher for symptomatic forms. When people were both affected by the virus and vaccinated with a single dose, the risk was only 0.53 times higher.
“This result may be explained by a more complete immune response resulting from natural infection,” the authors suggest. This difference appears to be specific to the Delta variant, as another study published in Nature on August 26, looking only at the Alpha and Beta variants, claims that serums from cured people provide “significantly less” protection than those from vaccinated people (this study, however, does not look at real data, but at laboratory measurements of antibody effectiveness). There may also be some bias in the statistics, such as asymptomatic people being counted less (since only those who tested positive are evaluated).
This does not mean that it is better to wait until you are naturally infected. According to the latest data, an unvaccinated person is seven times more likely to be hospitalized than a vaccinated person. “Taking the risk of dying in the name of immunity is a very bad calculation,” concludes Robert Schooley of the University of California.
In short, getting vaccinated is still the wisest move in order to avoid serious complications. Also, Pfizer will most likely release in the near future an updated version of its vaccine to protect against whatever strains the pandemic keeps throwing at us.
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