Reacción a "Reaction to two studies showing that covid-19 vaccines offer extra protection to those already infected"

Both studies confirm what is already known: that vaccines boost acquired immunity after natural infection with SARS-CoV-2, increasing protection, especially against severe disease.

Both the Brazilian and Swedish studies have the statistical power of large numbers of individuals. In both cases, the results provide valuable information on the rate of reinfection, and the consequences of reinfection, in individuals with natural immunity and in many cases subsequently vaccinated.

The major limitation of the two studies is that the data predate omicron, which is the currently predominant variant, and which has changed the landscape of reinfection possibilities. As has been shown, omicron is much more able than previous variants to escape the immunity (in terms of antibodies) provided by both infections with other variants and vaccination. Omicron can therefore cause reinfection more easily than previous variants, and therefore the results of these studies in terms of efficacy in preventing reinfection cannot be directly extrapolated to the current situation.