I have already had the COVID-19Should I get vaccinated?
Text updated on 2021-08-31
Yes, and only one dose of RNA vaccine is needed.
Most vaccines developed against COVID-19 require two injections. See the question What are the different types of vaccines against COVID-19 ?. The first injection will activate the immune system and the second, a few weeks later, will reactivate it and allow the immune system memory to be consolidated.
If you have had COVID-19 within the last year, this coronavirus infection SARS-CoV-2 is a first activation of the immune system and is equivalent to a first dose of vaccine. A single dose of RNA vaccine (Pfizer or Moderna vaccine) is sufficient to effectively consolidate the memory of the immune system. A single dose of vaccine is sufficient to increase the concentration of antibodies in the blood by up to 1,000 times, reaching levels similar to those obtained after two doses of vaccine in people who have not been previously infected.
After one dose of RNA vaccine, you will be as much or more protected than people who did not get the vaccine and who had two doses! COVID-19 and who had two doses of vaccine! The immune response induced by a single dose after being infected is also effective against the following variants: the Alpha variant (variant B.1.1.7 detected in Great Britain), the Beta variant (variant B.1.351 detected in South Africa), the Gamma variant (variant P1 detected in Brazil) and the iota variant (variant B.1.526 detected in New York).
This study shows that in subjects who have been infected with SARS-CoV-2 and who have had a symptomatic or asymptomatic form, the immune response (production of antibodies and memory B cells) is present from the first dose of RNA vaccine and is observed between 7 and 14 days after vaccination.Saadat, S., Tehrani, Z. R., Logue, J., Newman, M., Frieman, M. B., Harris, A. D., & Sajadi, M. M. (2021). Binding and neutralization antibody titers after a single dose in health care workers previously infected with SARS-CoV-2. Jama, 325(14), 1467-1469.
This study shows that in subjects who have been infected with SARS-CoV-2, the immune response (production of antibodies and memory B cells) is present from the first dose of RNA vaccine. The authors speak of a "boost" effect of the vaccine. Contrary to what is observed in subjects who have not been infected by SARS-CoV-2 and who are vaccinated, a first injection of the vaccine does not induce an increase in the immune response. The observed immune response is also effective against the Beta B.1.351 variant detected in South Africa.Goel, R. R., Apostolidis, S. A., Painter, M. M., Mathew, D., Pattekar, A., Kuthuru, O., ... & Wherry, E. J. (2021). Distinct antibody and memory B cell responses in SARS-CoV-2 naïve and recovered individuals following mRNA vaccination. Science immunology, 6(58).
In people who are already infected and seropositive for the coronavirus, a single dose of vaccine is sufficient to increase the concentration of antibodies in the blood by up to 1,000 times, reaching levels similar to those obtained after two doses of vaccine in people who have not been previously infected.Stamatatos, L., Czartoski, J., Wan, Y. H., Homad, L. J., Rubin, V., Glantz, H., ... & McGuire, A. T. (2021). mRNA vaccination boosts cross-variant neutralizing antibodies elicited by SARS-CoV-2 infection.
This study shows that after the first dose of RNA vaccines, the immune response in people who have been infected with SARS-CoV-2 is comparable to or even higher than that observed after two doses of vaccines in people who had not been previously infected with SARS-CoV-2. In people who have been previously infected, a second dose of vaccine does not induce an increased immune response.Krammer, F., Srivastava, K., Alshammary, H., Amoako, A. A., Awawda, M. H., Beach, K. F., ... & Simon, V. (2021). Antibody responses in seropositive persons after a single dose of SARS-CoV-2 mRNA vaccine. New England Journal of Medicine, 384(14), 1372-1374.
This study of people who have had the COVID-19 shows that immune defences against SARS-CoV-2 are present up to 12 months after infection. Vaccination with an RNA vaccine leads to an increase in the components of the immune response (antibodies and memory B cells) and effective protection against the B.1.1.7 (Alpha, detected in Great Britain), B.1.351 (Beta, detected in South Africa), B.1.526 (Iota, detected in New York) and P.1 (Gamma, detected in Brazil) variants.Wang, Z., Muecksch, F., Schaefer-Babajew, D., Finkin, S., Viant, C., Gaebler, C., ... & Nussenzweig, M. C. (2021). Naturally enhanced neutralizing breadth to SARS-CoV-2 after one year. bioRxiv.
This study shows that a single dose of RNA vaccine in people already infected with SARS-CoV-2 induces a greater response than that observed after two doses in people who have not been previously infected. This immune response is not dependent on the severity of the disease and is observed for infections up to 15 months before vaccination. The induced immune response is effective against the B.1.351 (Beta, detected in South Africa), P.1 (Gamma, detected in Brazil) and B.1.1.7 (Alpha, detected in Great Britain) variants.van Gils, M. J., Willegen, H. D., Wynberg, E., Han, A. X., van der Straten, K., Verveen, A., ... & RECoVERED Study Group. (2021). Single-dose SARS-CoV-2 vaccine in a prospective cohort of COVID-19 patients. medRxiv.
The Pfizer and Moderna RNA vaccines protect people who have not been previously infected with the coronavirus SARS-CoV-2 from the Delta B. 1.617. 2 variant. The study did not analyse previously infected individuals who were vaccinated with a single dose.Bernal, J. L., Andrews, N., Gower, C., Gallagher, E., Simmons, R., Thelwall, S., ... & Ramsay, M. (2021). Effectiveness of COVID-19 vaccines against the B. 1.617. 2 variant. medRxiv.