There’s a lot of uncertainty concerning how long immunity to COVID-19 lasts, both from the vaccines and from infection. Part of the reason for this confusion are the facts that the disease is still new, and that people’s immune responses differ based on a variety of factors that researchers are still exploring. Here’s what we know so far about COVID-19 immunity. 

COVID-19 Immunity 101 

When your immune system confronts a new virus, it stimulates the generation of antibodies that targets that virus for destruction. It can take a few days for your body to stockpile enough antibodies to mount a viable defense. Once activated, the antibodies linger in your blood, but taper off over the course of several weeks or months. 

Specialized T and B cells, however, are long-lived and remember the intruding germ. These cells wait in the wings to mobilize a major immune response should the same virus invade again. Researchers have found that COVID-19 antibodies are still present in the blood of most patients approximately six months after infection and that T and B cells are present for up to eight months. Current data suggests that COVID-19 immunity could potentially last for years.

Immunity after Infection and Recovery

Scientists are still studying the longevity of T and B cells generated to fight COVID-19. A study of 77 people who recovered from mostly mild cases showed that antibody levels dropped significantly in the four months after infection but then leveled off. Antibodies were still detected 11 months later, though it’s unclear what degree of antibody buildup is necessary to prove effective against infection. 

Even after SARS-CoV-2 infection, complete immunity is not guaranteed. The first documented case of reinfection occurred in August 2020. Your immune system can continue manufacturing T and B cells against specific viruses for years after infection. Some people infected with the SARS-CoV-1 virus responsible for the 2002-2004 SARS outbreak still have T and B cells related to that infection, and even a number of survivors of the 1918 flu pandemic retained a degree of immunity to that particular virus almost 90 years later. 

Immunity after Vaccination 

The protective antibody levels of all three COVID-19 vaccines used in the U.S. begin to decline a few months after vaccination. Experts think this may explain the increase in infections in vaccinated individuals about four months following the vaccine rollout. The Delta variant may be another contributor, as it differs enough from the original virus to avoid recognition by antibodies.  

For those who fear that the waning of antibody levels means your immunity is at an end, that is not the case. While the degree of immunity may not prevent infection and mild illness, it does reduce the risk of severe illness, hospitalization, complications, and death from the disease. 

So Should I Get Vaccinated?

Public health officials encourage vaccination even for people who recover from COVID-19 and those who test positive but are asymptomatic. Research shows that vaccination after COVID-19 infection and recovery increases the level of protective antibodies more than an infection does alone. Of those who have been infected, unvaccinated people are more likely than vaccinated people to get COVID-19 again. There is still much to learn about COVID-19 immunity. Research and clinical trials are ongoing. 

*Fink, J. (2021, Oct. 16). How Long COVID-19 Immunity Lasts. Healthgrades.

https://www.healthgrades.com/right-care/coronavirus/how-long-covid-19-immunity-lasts?cid=63emHLN101121COVID

Much about the novel coronavirus, i.e., COVID-19, is still not fully understood. As research progresses and our knowledge of the virus increases, information can change rapidly. We strive to update all of our articles as quickly as possible, but there may occasionally be some lag between scientific developments and our revisions.