Immune memory against the virus is also potential good news for vaccine developers.
Recent findings published in the online edition of Science, have found that nearly all survivors of the coronavirus disease 2019 (COVID-19) have immune cells that are necessary to fight a re-infection. This suggests that people who have had the virus have protective immunity against the deadly disease for months, potentially even years, after their infection.
Investigators analyzed blood samples from 188 patients who had survived an infection with COVID-19, and found that the key players In the immune system responsible for fighting off the specific pathogens related to SARS-CoV-2 can last in an individual’s system for at least 8 months after they have begun to experience symptoms. The virus-specific antibodies were also found to persist in the bloodstream for months after an infection.
"We measured antibodies, memory B cells, helper T cells and killer T cells all at the same time," Shane Crotty, co-leader on the study said. "As far as we know, this is the largest study ever, for any acute infection, that has measured all four of those components of immune memory."
Another important finding demonstrated that the body produced memory B immune cells that help to fight off the virus, having them ready to be reactivated in the case of another COVID-19 infection. 6 Months after the initial infection, investigators discovered that the immune system also created specific memory B cells for the SARS-CoV-2 spike protein, which the virus uses to initiate an infection in human cells.
Survivors of the virus also produced T cells, memory CD4+ helper T cells and Cb8+ killer T cells, which remained in the body after the infection. These different parts of the immune system all work together to fight off a COVID-19 infection, and they were all found in the blood of participants for over 8 months after being sick.
"It is possible that immune memory will be similarly long-lasting following vaccination, but we will have to wait until the data come in to be able to tell for sure," Daniela Weiskopf, another co-author on the study said. "Several months ago, our studies showed that natural infection induced a strong response, and this study now shows that the responses lasts. The vaccine studies are at the initial stages, and so far, have been associated with strong protection. We are hopeful that a similar pattern of responses lasting over time will also emerge for the vaccine-induced responses."