Antibodies and T Cell Responses to COVID-19 Virus Persist Three Months After Infection
April 26, 2021
- SARS-CoV-2 has caused a pandemic that affects many countries with more than 13 million cases and at least 570,000 deaths as of July 15, 2020.
- Modeling research studies have shown that SARS-CoV-2 infection can produce immunity to reinfection for at least one year.
- A number of studies reported that patients infected with SARS-CoV-2 can produce an antibody response.
- However, reported data had focused mainly on hospitalized patients where only virus-specific IgG and IgM antibodies were analyzed.
- One study found that all their patients are seropositive for IgG and neutralizing antibodies 41 to 53 days after illness onset.
- In another study, researchers detected neutralizing antibodies and high concentration of IgG in most of their patients that are newly discharged or two weeks after discharged.
- In a recent study, neutralizing antibodies were detected in patients 8 weeks after discharged however, the concentration decreased significantly and about 13% of the symptomatic patients become negative for IgG antibody at the start of the convalescent stage.
- The convalescent stage refers to the late stage of infection where a patient starts to recover and returns to normal health, but may still be able to transmit the disease to others.
- These data suggest seeking more information about protective immunity and the proper amount of time that should be recommended for quarantine.
- Other researchers pointed to T cells as the potential key to solving this problem.
- Memory T cells specific to SARS-CoV-2 have been observed in the peripheral blood of one-case patient two weeks after the start of symptoms.
- Also, a number of studies reported the presence of CD8+ and CD4+ T cells specific to SARS-CoV-2 in most of the COVID-19 convalescent patients 3 to 5 weeks after the start of symptoms.
- A lot of studies can provide useful information about protective immunity however, the dynamics, duration, and nature of immunity produced during SARS-CoV-2 infection are still not well understood.
- In this study, researchers measured virus-neutralizing antibodies, antibodies against the spike protein, receptor binding domain, nucleoprotein of SARS-CoV-2, and the T cell responses up to 121 days after the start of symptoms.
- The study includes 25 patients infected with SARS-CoV-2.
- IgG against SARS-CoV-2 proteins as well as IgM against the receptor-binding domain was detected in all patients by 14 days after the start of symptoms with peak levels achieved by 15 to 30 days at the start of symptoms.
- Additionally, all patients produced neutralizing antibodies.
- The IgG and neutralizing antibodies were detectable 3 to 4 months after the start of symptoms.
- However, the concentration of IgM antibodies rapidly declined.
- About 65% of the patients have CD4+ or CD8+ T cell responses specific to COVID-19 virus 3 to 4 after the start of symptoms.
- The results provide important information that IgG, neutralizing antibodies, and T cell responses continue in most of the patients for at least 3 to 4 months after infection.
Jiang, X. L., Wang, G. L., Zhao, X. N., Yan, F. H., Yao, L., Kou, Z. Q., Ji, S. X., Zhang, X. L., Li, C. B., Duan, L. J., Li, Y., Zhang, Y. W., Duan, Q., Wang, T. C., Li, E. T., Wei, X., Wang, Q. Y., Wang, X. F., Sun, W. Y., Gao, Y. W., … Ma, M. J. (2021). Lasting antibody and T cell responses to SARS-CoV-2 in COVID-19 patients three months after infection. Nature communications, 12(1), 897. https://doi.org/10.1038/s41467-021-21155-x Cole WH, Keeton RW, Calloway NO, Glickman N, Mitchell HH, Dyniewicz J, Howes D (October 1947). “Studies in Postoperative Convalescence”. Annals of Surgery. 126 (4): 592–609. doi:10.1097/00000658-194710000-00017. PMC 1803419. PMID 17859018