Throughout the COVID-19 pandemic, there has been much uncertainty about how long immunity lasts after an unvaccinated person is infected with SARS-CoV-2.
In a new study from Yale and elsewhere, researchers found strong protection following natural infection is short-lived.
They say reinfection can reasonably happen in three months or less. Therefore, those who have been naturally infected should get vaccinated. Previous infection alone can offer very little long-term protection against subsequent infections.
The study is the first to determine the likelihood of reinfection following natural infection and without vaccination.
The team analyzed known reinfection and immunological data from the close viral relatives of SARS-CoV-2 that cause “common colds,” along with immunological data from SARS-CoV-1 and Middle East Respiratory Syndrome.
The team found reinfections can, and have, happened even shortly after recovery. And they will become increasingly common as immunity wanes and new SARS-CoV-2 variants arise.
As new variants arise, previous immune responses become less effective at combating the virus. Those who were naturally infected early in the pandemic are increasingly likely to become reinfected in the near future.
The team’s data-driven model showed striking similarities to the reinfection risks over time between SARS-CoV-2 and endemic coronaviruses.
They say that just like common colds, from one year to the next people may get reinfected with the same virus. The difference is that, during its emergence in this pandemic, COVID-19 has proven to be much more deadly.
A hallmark of the modern world is going to be the evolution of new threats to human health. Evolutionary biology—which provided the theoretical foundations for these analyses—is traditionally considered a historical discipline.
The current findings underscore its important role in informing decision-making, and provide a crucial steppingstone toward robust knowledge of our prospects of resistance to SARS-CoV-2 reinfection.
If you care about COVID vaccines, please read studies about people who had COVID-19 may only need one vaccine dose and findings of straight answers to common questions about COVID-19 vaccines.
For more information about the COVID vaccine and your health, please see recent studies about vaccine side effects don’t tell you how well your immune system will protect you from COVID-19 and results showing that 1 in 4 people experience mild side effects from COVID-19 vaccines.
The study is published in The Lancet Microbe. One author of the study is Jeffrey Townsend.
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