How Long Can the Immunity Against COVID-19 Protect Us from Reinfection

There has been major concern about the protective power of immunity against the novel coronavirus. Many people have asked: how long can the immunity, once acquired by the previous infection or vaccination, protect us from the COVID-19 reinfection?

In February of 2021, a group of researchers reported that the immunity to COVID-19 could last for up to eight months. But a recent research paper published in the Journal Nature on June 14 demonstrated that the protective immunity could last for at least one year, which is very encouraging news.

The researchers analyzed clinical and laboratory data collected from 63 COVID-19-convalescent individuals. Among the 63 individuals, 26 have received mRNA vaccines. Their data showed that the virus-fighting antibody reactivity to the receptor-binding domain (RBD) of the novel coronavirus, SARS-CoV-2, antibody’s neutralizing activity, and the number of RBD-specific memory B cells remain relatively stable from 6 to 12 months. For those who received mRNA vaccines, all components of the humoral immune responses increased. More importantly, those individuals who received an mRNA vaccine developed a broader and stronger COVID-19-fighting immunity because the titer of their neutralizing antibodies and the number of their memory B cells are higher, and their antibodies are even effective to certain types of virus variants.

Although we need to see sufficient data from more studies to get a clear answer on the protective power of immunity to COVID-19, the result of this study is still very encouraging as it shows that the immunity in convalescent individuals is long-lasting, and the mRNA vaccines would boost the immunity of convalescent individuals. We look forward to seeing further data that demonstrates a similar broader and stronger immunity against COVID-19 achieved through mRNA vaccination to those who have not been infected—which would be critical to control the pandemic quickly and more effectively.