Dr. John Zurlo breaks down the difference between natural immunity and vaccine-induced immunity, and why COVID-19 vaccination remains critical.
If you’re wondering if recovering from COVID-19 means you are immune to reinfection with the virus, you’re not alone. Many people think that natural immunity protects you from future infection, but the truth is that those who have had COVID-19 can get it again. Vaccination is thought to further reduce that chance.
Both natural and vaccine-induced immunity result in the production of antibodies and certain immune cells that help to fight off the virus when we’ve been exposed. Yet that doesn’t mean that the immunity is fully effective in preventing us from getting the virus. But immunity does help protect us from severe illness and death. To help us learn more about the role of antibodies, and what it means to have natural immunity, we spoke with Dr. John Zurlo, Chair of the Jefferson COVID-19 Task Force and Division Director of Infectious Diseases at Thomas Jefferson University Hospital.
What do antibodies protect us from?
Antibodies are proteins the body creates to help ward off harmful germs and pathogens. Antibodies are part of a broader immune response our bodies generate to infections. The body creates antibodies in one of two ways: through direct contact with an active virus or through vaccination.
“Early data leads us to believe that those who have had COVID-19 have some level of immunity—and we think that antibodies help protect against variants of the virus as well,” says Dr. Zurlo. “We know, for example, that vaccines have significant efficacy even against variants such as Delta.”
Overall, it’s important to keep in mind that while antibodies produced due to natural and vaccine-induced immunity can help defend our bodies against the virus, they won’t necessarily completely prevent future illness or stop the spread of COVID-19.
What does it mean to have natural immunity?
Natural immunity is acquired when the immune system has built antibodies against a disease through direct interaction with the live virus. In terms of COVID-19, Dr. Zurlo says that people who have gotten the virus may be somewhat protected from getting it again, but it’s not a guarantee.
“People who recover from COVID-19 undoubtedly have some degree of natural immunity, but it depends on the severity of the illness they experienced,” says Dr. Zurlo. “Just like we see with other infections, a mild case of COVID-19 may result in having a light natural immune response. Likewise, a severe case of COVID-19 is likely to result in a stronger immune response.”
Why is it important to still get vaccinated?
Data suggests those who are vaccinated and have had COVID-19 show a stronger immune response to the virus than those who are just vaccinated. Even if you’ve had the virus before, remaining unvaccinated means a higher risk of contracting it again, being less able to fight off new variants, and the risk of spreading it to other people.
“Though a combination of vaccination and previous infection probably have some benefits in fighting off COVID-19, it is certainly not recommended to purposefully expose yourself to the virus,” says Dr. Zurlo. “Not only are we uncertain about how much natural immunity to COVID-19 someone might have, we also don’t know how long the immunity will last.” It will take time to determine the true measures of immunity to COVID-19 and the duration of immunity from both natural infection and vaccination.
Getting vaccinated is proven to reduce the chance of getting COVID-19, as well as to protect against severe illness in cases in which vaccinated people do get the virus. We believe that all patients who have had COVID-19 infection should be vaccinated.