- For those who recover from COVID-19, immunity to the virus can last at least 8 months and maybe longer, research shows.
- Immunity can occur naturally after developing COVID-19 or from getting the COVID-19 vaccination.
- Because the length of immunity after developing COVID-19 or getting the vaccine is unknown, practicing physical or social distancing and wearing a mask need to continue to stop the spread.
Whether you’ve recovered from COVID-19, received the vaccine, or neither, understanding immunity and how long it lasts can help give you important insight into how you can interact safely with others during the pandemic. First, it helps to know what immunity means. There are two types of immunity: natural and vaccine-induced.
How natural immunity works after COVID-19 develops
After a person acquires a virus, the immune system retains a memory of it. Immune cells and proteins that circulate in the body can recognize and kill the pathogen if it’s encountered again, protecting against disease and reducing illness severity.
The components of immunity protection include:
- Antibodies, which are proteins that circulate in the blood and recognize foreign substances like viruses, and neutralize them.
- Helper T cells help to recognize pathogens.
- Killer T cells kill pathogens.
- B cells make new antibodies when the body needs them.
People who recover from COVID-19 have been found to have all four of these components. However, specifics about what this means for the immune response and how long immunity lasts are not clear.
According to Lauren Rodda, PhD, a senior postdoctoral fellow in immunology at the University of Washington School of Medicine, we don’t know for certain if people are immune to re-infection simply because not enough studies have been done yet. This would require tracking the re-exposure of a significant number of people and determining if they get sick.
Knowledge in this area continues to grow; however, as new studies are conducted. Most recently, a study published in the journal Science has found that immunity can last for as long as 8 months. According to Shane Crotty, PhD, a professor at the La Jolla Institute for Immunology in California who co-led the study, his team measured all four components of immune memory in almost 200 people who had been exposed to SARS-CoV-2, which causes COVID-19, and recovered.
The researchers found that the four factors persisted for at least 8 months following infection with the virus. This is important because this shows that the body can “remember” SARS-CoV-2. If it encounters the virus again, the memory B cells can quickly gear up and produce antibodies to fight it.
Those who have recovered from COVID-19 could have immunity for months or perhaps even years, the authors said. Before this latest study, Rodda said work had been done by her research team and others, showing that antibodies are maintained for at least 3 months. In her team’s study, in particular, it was shown that this occurs even in people who have mild symptoms. Their study also suggested that immunity could last much longer.
In a different study published in The New England Journal of Medicine, researchers in Iceland studied 1,107 people who had recovered from COVID-19 and tested positive for the antibodies. Over a 4-month period, they found that those COVID-19 antibodies did not decline. A study published in the journal Immunity found that people who recover from even mild cases of COVID-19 produce antibodies for at least 5 to 7 months and could last much longer.