Neutralizing antibodies against SARS-CoV-2 variants induced by natural infection or vaccination: a systematic review and pooled meta-analysis.

Recently emerged SARS-CoV-2 variants may pose a threat to immunity. A systematic landscape of neutralizing antibodies against emerging variants is needed. We systematically searched for studies that evaluated neutralizing antibodies titers induced by previous infection or vaccination against SARS-CoV-2 variants and collected individual data. We identified 106 studies meeting the eligibility criteria. Lineage B.1.351 (Beta), P.1 (Gamma) and B.1.617.2 (Delta) significantly escaped natural-infection-mediated neutralization, with an average of 4.1-fold (95% CI: 3.6-4.7), 1.8-fold (1.4-2.4), and 3.2-fold (2.4-4.1) reduction in live virus neutralization assay, while neutralizing titers against B.1.1.7 decreased slightly (1.4-fold, 95%CI: 1.2-1.6). Serum from vaccinees also led to significant reductions in neutralization of B.1.351 across different platforms, with an average of 7.1-fold (5.5-9.0) for non-replicating vector platform, 4.1-fold (3.7-4.4) for mRNA platform, and 2.5-fold (1.7-2.9) for protein subunit platform. Neutralizing antibodies levels induced by mRNA vaccines against SARS-CoV-2 variants were similar, or higher, than that derived from naturally-infected individuals.