The outcomes of a latest study published in The Journal of Clinical Investigation raised questions regarding the use of a second mRNA vaccine in COVID-19 recovered patients. Also, the time to attain herd immunity can be reduced if millions of vaccine doses may be redirected to people who have not be exposed to COVID-19.

Alessio Mazzoni and researchers deduced the effect of two doses of COVID-19 vaccination (BNT162b2) in COVID-19 recovered compared to people who never had COVID-19, i.e. naive subjects.

The COVID-19 spike-specific T and B cell responses, plus especially Immunoglobulin (IgG, IgA, IgM) and neutralizing antibodies titers in 22 people who were given COVID-19 vaccine were evaluated. Eleven out of 22 patients had a history of SARS-CoV-2 infection. Evaluations were carried out prior to vaccination and then per week until 7 days after the second vaccine.

Clearly, one vaccine dose was appropriate to increase both cellular and humoral immune response in COVID-19 recovered individuals. The administration of second dose did not provide extra improvement. But, the second dose was crucial in naive subjects to further boost the immune response. These findings were further strengthened based on the serological level in naïve (68 individuals) and COVID-19 recovered (29 individuals), with a follow-up of 50 days after the vaccination.