The neutralizing response to SARS-CoV-2 Omicron variants BA.1 and BA.2 in COVID-19 patients and homologous and heterologous vaccinees

ABSTRACT

The rapid replacement of Omicron BA.1 by BA.2 sublineage is very alarming, raising the question of whether BA.2 can escape the immunity acquired after BA.1 infection. We compared the neutralizing activity toward the Omicron BA.1 and BA.2 sub-lineages in five groups: COVID-19 patients; subjects who had received two doses of mRNA vaccine; subjects naturally infected with SARS-CoV-2 who had received two doses of mRNA; and subjects who had received three doses of homologous or heterologous vaccine. The results obtained highlight the importance of vaccine boosters in eliciting neutralizing antibody responses against Omicron sub-lineages, and suggest that the adenovirus vectored vaccine elicits a lower response against BA.1 than against BA.2 sub-lineage.

KEYWORDS:

• Hybrid immunity
• mRNA booster
• neutralizing antibodies
• Omicron BA.1
• Omicron BA.2
• SARS-CoV-2
• SARS-CoV-2 vaccines

Acknowledgement

The authors thank Ida Paciello and Giulio Pierleoni for their technical assistance.

Disclosure statement

FD, ML, CS, PP, GP, LB, E. Molesti and A.M. are employed by VisMederi srl. M.L. and L.B. are employed by VisMederi Research srl. R.R. is an employee of the GSK group of companies. E.A. and R.R. are listed as inventors of full-length human monoclonal antibodies described in Italian patent applications n. 102020000015754 filed on June 30th 2020, 102020000018955 filed on August 3rd 2020 and 102020000029969 filed on 4th of December 2020, and the international patent system number PCT/IB2021/055755 filed on the 28th of June 2021. All patents were submitted by Fondazione Toscana Life Sciences, Siena, Italy. CMT is an external consultant of VisMederi Research srl. E. Montomoli is founder and Chief Scientific Officer of VisMederi srl and VisMederi Research srl.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This project has received funding from the University of Siena as part of “Piano di Sostegno alla Ricerca 2021 (PSR-2021)” program, “Curiosity-driven (F-CUR)”, research grant “COVI-VAC – Valutazione della risposta immunitaria umorale in seguito alla somministrazione di un vaccino a mRNA anti COVID-19 in una struttura penitenziaria di tipo sanitario.”