Longer intervals between SARS-CoV-2 infection and mRNA-1273 doses improve the neutralization of different variants of concern

The humoral immune response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern elicited by vaccination was evaluated in COVID-19 recovered individuals (Rec) separated 1-3 months (Rec2m) or 4-12 months (Rec9m) postinfection and compared to the response in naive participants. Antibody-mediated immune responses were assessed in 66 participants by three commercial immunoassays and a SARS-CoV-2 lentiviral-based pseudovirus neutralization assay. Immunoglobulin (Ig) levels against SARS-CoV-2 spike were lower in naive participants after two doses than in Rec after a single dose (p < 0.05). After two doses in Rec, levels of total Ig to receptor-binding domain were significantly increased in Rec9m compared to Rec2m (p < 0.001). The neutralizing potency observed in Rec9m was consistently higher than in Rec2m against variants of concern (VOCs) Alpha, Beta, Delta, and BA.1 sublineage of Omicron with 2.2-2.8-fold increases. Increasing the interval between SARS-CoV-2 infection and the vaccination with messenger RNA-based vaccines to more than 3 months generates a more efficient heterologous humoral immune response against VOCs by allowing enough time to mount a strong recall memory B cell response.

Automated summary

The humoral immune response against SARS-CoV-2 variants of concern after vaccination was evaluated in COVID-19 recovered individuals. It was found that recovered individuals had higher levels of antibodies after a single dose compared to naive participants after two doses. Furthermore, antibodies against the receptor-binding domain were higher in individuals who had recovered for 4-12 months compared to those who had recovered for 1-3 months, and the neutralizing potency against variants of concern was also higher in the longer recovered group.