People with past COVID-19 benefit from immunisation
Some patients with past SARS-CoV-2 infections think they have been "naturally immunised" and would not benefit from COVID-19 vaccination. Two new studies add to the evidence showing that vaccination generates a more vigorous B and T cell response than does natural infection and that vaccination is particularly potent in people with previous SARS-CoV-2 infections.
Researchers evaluated people who were vaccinated (with an mRNA vaccine) after natural infection and people who were vaccinated but had no prior natural infection. In people who were vaccinated after natural infections, neutralising antibodies against the beta variant were 25 times higher than after vaccination alone and 100 times higher than after natural infection alone. This result was remarkable, given that natural infections were almost never with the beta variant and that vaccines did not target the beta-variant spike protein. Memory B cells against SARS-CoV-2 were 5- to 10-fold higher when vaccination followed natural infection than after natural infection or vaccination alone.
After natural infection, immunological memory (both B and T cells) persists for at least 8 months (and probably longer). Natural protection against symptomatic reinfection with the initial strain, as well as the alpha variant, is between 93% and 100%, even after asymptomatic infection. People who have had COVID-19 are well advised to be vaccinated.