Studies on the COVID vaccine and those who have had COVID in recent months have concluded that infection-induced immunity could last for months; receiving a vaccine on top of this can make infection-induced immunity last much longer. These individuals may also not need a booster shot later on.
According to a study done by Nature, the immune cells located in bone marrow are able to memorize the structure of the coronavirus and create protective antibodies against it in order to prevent future reinfection. In another study, which has not yet been peer reviewed, researchers found that these antibodies can strengthen over time.
“The data suggest that immunity in convalescent individuals will be very long lasting and that convalescent individuals who receive available mRNA vaccines will produce antibodies and memory B cells that should be protective against circulating SARS-CoV-2 variants,” stated the researchers of this article.
When infection in the body happens, the immune system will make antibodies against the virus during the period of infection. After the infection is cleared, many of the antibodies made against the virus decline over time and the body begins to create memory B cells. These cells are circulated around the body, ready to begin protective measures if infection occurs. At the same time, bone marrow plasma cells (BMPCs), are stored in the bone marrow, slowly releasing antibodies throughout our lifetime.
Initially, researchers were worried, as severe cases of COVID-19 caused a decline in the production of BMPCs instead of causing a spike as most viral infections do. However, after some time, researchers discovered that the production of BMPCs that could detect the SARS-CoV-2 spike protein were still detectable in the body. The study showed that the Pfizer mRNA vaccine can trigger the same type of cell production.
Even with immunity from previous infection, it is still important to get vaccinated. Most studies show infection-induced immunity to last up to 11 months. It is also still possible to become reinfected with COVID and spread it to others, getting vaccinated can help reduce the possibility of reinfection and possible spread. The antibodies received from the vaccine are also different from the ones received from infection.
With this, studies have shown that those who have had a previous COVID-19 infection and are vaccinated will not likely need a booster due to the strong immune reaction that occurs from the antibodies caused by both previous infection and vaccination.
Vaccinated people who haven’t had a previous infection, on the other hand, will likely need the booster shot, along with those who did not have had a strong immune response to a previous COVID-19 infection.
Dr. Len Horovitz, a pulmonary specialist at Lenox Hill Hospital in New York, stated “someone who’s had COVID-19, gets immunized, never have to have a booster, they have more immunity than someone who’s been vaccinated [and never had a previous infection], it would seem.”
Overall, experts say that, although reinfection is not uncommon, it is still possible. But, being vaccinated if you’ve had a previous infection can significantly boost immunity. Those who have had COVID-19 may not require booster shots in order to maintain protection against the virus.