Michael Hunter, MD on Medika Life

Got Covid? How Long Do You Have Protection After Catching the Virus?

HAVING COVID-19 PROVIDES DURABLE (BUT TEMPORARY) protection against getting severely sick in the future, no matter the variant. That is the finding of a new study from the University of Washington (USA).

COVID-19 re-infection re-infection risk is relatively low, but not zero. Studies suggest that people who have had COVID-19 may have some level of immunity to the virus, at least for a certain period. However, this immunity may not be long-lasting and may vary depending on a person’s age, overall health, and other factors.

The risk of re-infection also depends on the prevalence of the virus in a person’s community and their level of exposure to it. If someone is exposed to the virus again, their immune system may be able to recognize and fight off the virus more quickly, potentially resulting in milder symptoms.

Several studies have reported cases of COVID-19 re-infection, although these cases appear relatively rare. The Centers for Disease Control and Prevention (CDC) has stated that re-infection with COVID-19 is uncommon within 90 days of the initial infection.

However, it is still important to follow public health guidelines to prevent the spread of the virus, even if you have previously been infected. Mitigation strategies include wearing a mask, practicing physical distancing, and getting vaccinated when a vaccine is available to you.

Let’s explore the most comprehensive data compiled to analyze national immunity protection against the virus. The researchers recently published their findings in The Lancet.

“I didn’t expect to recover from my second operation but since I did, I consider that I’m living on borrowed time. Every day that dawns is a gift to me and I take it in that way. I accept it gratefully without looking beyond it. I completely forget my physical suffering and all the unpleasantness of my present condition and I think only of the joy of seeing the sun rise once more and of being able to work a little bit, even under difficult conditions.”
― Henri Matisse

Covid-19 infection and future risk reduction

Researchers analyzed 65 studies from 19 countries. Let’s get right to the bottom-line conclusion of the study authors:

[The] meta-analyses showed that protection from past infection and any symptomatic disease was high for (COVID-19) ancestral, alpha, beta, and delta variants but were substantially lower for the Omicron BA.1 variant. A Covid infection provided some protection against re-infection from the original (ancestral), alpha, and delta variants. While the risk reduction diminished over time, it remained at 79 percent at 40 weeks.

Protection against re-infection by the Omicron BA.1 variant diminished more quickly, reaching 36 percent at 40 weeks.

Photo by Kate Trifo on Unsplash

Protection from re-infection from ancestral, alpha, and delta variants declined over time but remained 78.6 percent at 40 weeks (around ten months).

The report notes that protection against re-infection by the Omicron BA.1 variant declined more rapidly and was estimated at 36 percent over that same 40-week period.

Covid infection and future severe infection

What about severe infection? Having an infection protects against severe infections from future infections. More specifically, the protection was 90.2 percent for the original, alpha, and delta variants and 88.9 percent for Omicron BA.1 at 40 weeks (about ten months).

As protection appears to wane over time, even individuals with natural immunity will likely still need an annual COVID booster shot to maximize risk reduction for severe illness.


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Michael Hunter, MD
Michael Hunter, MD
I received an undergraduate degree from Harvard, a medical degree from Yale, and trained in radiation oncology at the University of Pennsylvania. I practice radiation oncology in the Seattle area.

Michael Hunter, MD

I received an undergraduate degree from Harvard, a medical degree from Yale, and trained in radiation oncology at the University of Pennsylvania. I practice radiation oncology in the Seattle area.

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