COVID Vaccine or Natural Immunity

Everywhere you look, people play sports, drive cars, and do their jobs outfitted with the latest safety equipment. Few people would think about buying a car without airbags or playing football without a helmet. But, people sometimes assume that if they have been infected with COVID-19, they have developed natural immunity and that they are unlikely to get infected again. I can see the logic. “Natural” immunity, like “natural” food, must be better, they think. In this case, though, the science of vaccines—like the science that has given the safety advances in countless areas of our lives—holds some powerful benefits.

COVID cases and individuals vary. People can get a mild case of COVID or a severe one. Their response to infection may have been vigorous or weak. Because there are so many variables, it is difficult to tell whether a person who has been infected is protected to the extent necessary to prevent another infection. Vaccines, on the other hand, are consistent and most people’s bodies respond in a predictable way to make protective levels of antibodies.

Vaccines offer better protection than natural immunity does. A recent study showed that the odds of a laboratory-confirmed case of COVID-19 was more than 5½ times higher among those who had already had COVID than those who had been vaccinated. A study from Kentucky measured people’s risk of reinfection among unvaccinated previously infected people at more than twice as high compared to those who had been vaccinated. COVID infection does provide protection against reinfection for 3 – 6 months, but this is quite variable between individuals. 

Isn’t there a test to see if you’re immune? There are several tests that will tell you if you have developed antibodies for COVID. Antibodies can increase and decrease over time without indicating much about how protective they are against getting another infection. While higher levels of neutralizing antibodies generally signal higher protection, scientists don’t yet know what level of neutralizing antibodies is necessary to provide protection. So while it seems like the test would tell you if you’re immune, currently it actually only tells you whether or not you’ve been exposed to COVID. As we learn more about antibody responses to infection and vaccines, we will have a better understanding of what it takes to be fully immune. Until then, it isn’t worth taking the risk that you might still have immunity following infection without the predictable response to vaccination. 

Getting the vaccine after you’ve recovered from COVID is safe. If you are currently sick with COVID, wait until you have recovered and met the criteria for discontinuing isolation to get vaccinated. If you were treated with monoclonal antibodies or convalescent plasma, you should wait 90 days. Talk to your doctor if you are uncertain about what treatments you received or if you have a history of multisystem inflammatory syndrome, as this may also affect how long to wait before getting vaccinated.  For most people, there is no risk and plenty of advantages in getting vaccine as soon as possible after COVID.

Just as I would encourage my patients to wear a seatbelt, I encourage my patients to get vaccinated even if they have already had COVID-19. In this case and many others, the advances afforded to us by science really make a difference in our health and survival.

Marie George, MD, FIDSA, is an infectious disease specialist at Southwestern Vermont Medical Center in Bennington.