Short-Lived Immunity to Seasonal Coronaviruses
An important facet to ending the COVID-19 pandemic is the development of long-lasting immunity to SARS-CoV-2, the novel coronavirus that causes COVID-19, either from natural infection or vaccines. Data will not be available to answer this question for SARS-CoV-2 for many months or years.
Scientists are trying to gain some insight into SARS-CoV-2 immunity by studying long-term data on reinfections with other seasonal coronaviruses. A recent study published in Nature Medicine examined blood samples collected continuously from 10 healthy individuals since the 1980s for evidence of infection and reinfections with four common seasonal coronaviruses that cause more benign respiratory illnesses. These individuals had been enrolled for decades in the Amsterdam Cohort Studies on HIV-1 infection and AIDS.
To detect coronavirus reinfections, they measured increases in antibodies to the nucleocapsid antigen of each coronavirus. An increase in antibody level was considered to be evidence that a person had mounted an immune response to a new infection with one of the four coronaviruses. A total of 513 blood samples were collected at regular intervals of 3 to 6 months. Between 3 and 17 coronavirus infections were discovered per study participant over more than 35 years. Reinfections occurred every 6 to 105 months, with the most common interval being 12 months after a previous infection.
This study showed that reinfections with common coronaviruses are a common occurrence and that immunity was short-lived. These findings are consistent with early evidence that antibodies to SARS-CoV-2 decrease within two months of infections. It also suggests that similar patterns of reinfection with SARS-CoV-2 may emerge in the coming months and years.
This study had at least three limitations. First, the researchers monitored antibody levels but did not have access to information about actual illness. It is possible that a rise in antibodies to a particular coronavirus might have provided exactly the response needed to convert a significant respiratory illness to a mild cold or no illness at all. Second, sustained immunity to viruses will always be disrupted if a virus is mutating. Third, the role of cell-based immunity in fighting off coronavirus infections is likely to be important but wasn’t studied.
If immunity proves to be transient, the best way to prevent infection will remain social distancing, wearing a mask, avoiding crowded indoor gatherings and handwashing.
References:
[1] Seasonal coronavirus protective immunity is short-lasting. Edridge AWD, Kaczorowska J, Hoste ACR, Bakker M, Klein M, Loens K, Jebbink MF, Matser A, Kinsella CM, Rueda P, Ieven M, Goossens H, Prins M, Sastre P, Deijs M, van der Hoek L. Nat Med. 2020 Sep 14. doi: 10.1038/s41591-020-1083-1. [Published online ahead of print.]
[2] Rapid decay of anti-SARS-CoV-2 antibodies in persons with mild Covid-19. Ibarrondo FJ, Fulcher JA, Goodman-Meza D, Elliott J, Hofmann C, Hausner MA, Ferbas KG, Tobin NH, Aldrovandi GM, Yang OO. N Engl J Med. 2020 Sep 10;383(11):1085-1087.
3. Francis Collins, Study finds people have short-lived immunity to seasonal coronaviruses, NIH Directors blog, September 29th, 2020
