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COVID-19 and immunity: What we know so far

If you've had COVID-19, does that mean you're immune to the coronavirus?

The answer is a resounding "maybe," according to experts at Johns Hopkins University. People who have recovered from COVID-19 usually have antibodies against the virus. That may offer them some protection from getting infected again. But scientists aren't sure how strong that protection is or how long it lasts.

It might depend on how severe the original infection was. A more severe infection might result in a higher level of immunity. A mild infection could lead to a lower level of immunity.

Infected again? It's possible

There have also been a handful of cases where a person has had a second infection after recovering from the first. In some of them, the second infection proved worse than the first.

These cases of reinfection show that people who have had COVID-19 may still be at risk from the virus. That means they still need to adhere to safety guidelines, such as:

  • Wearing face masks.
  • Staying 6 feet away from others in public.
  • Washing hands often.
  • Not touching their eyes, nose or mouth with unwashed hands.

What about herd immunity?

Herd immunity occurs when enough people are immune to a virus that it slows the spread through a community. But we're not likely to reach the numbers required for herd immunity through natural infections alone. And doing so could have a high cost in illness and death.

A safer way is to create herd immunity through a vaccine. One good thing about coronaviruses is that they mutate more slowly than many other viruses. Flu viruses, for instance, mutate quickly. That's why we need a new flu shot every year.

But SARS-CoV-2 (the virus that causes COVID-19) appears to change slowly. That gives hope that an effective vaccine could create herd immunity if enough people get it.

Want to learn more about slowing the spread of COVID-19? Visit our Coronavirus health topic center.

Reviewed 11/3/2020

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