Antibody responses after a single dose of ChAdOx1 nCoV-19 vaccine in healthcare workers previously infected with SARS-CoV-2.

Sebastian Havervall,Henry Ng,Elisa Pin,Nina Greilert-Norin,Charlotte Thålin,Mia Phillipson,Kim Blom,Sara Mangsbo,Peter Nilsson,Jonas Klingström,Ulrika Marking,Sophia Hober,Mikael Åberg,Cecilia Hellström,Ann-Christin Salomonsson,Max Gordon

doi:10.1016/j.ebiom.2021.103523

Abstract

BackgroundRecent reports demonstrate robust serological responses to a single dose of messenger RNA (mRNA) vaccines in individuals previously infected with SARS-CoV-2. Data on immune responses following a single-dose adenovirus-vectored vaccine expressing the SARS-CoV-2 spike protein (ChAdOx1 nCoV-19) in individuals with previous SARS-CoV-2 infection are however limited, and current guidelines recommend a two-dose regimen regardless of preexisting immunity.MethodsWe compared RBD-specific IgG and RBD-ACE2 blocking antibodies against SARS-CoV-2 wild type and variants of concern following two doses of the mRNA vaccine BNT162b2 in SARS-CoV-2 naïve healthcare workers (n=65) and a single dose of the adenovector vaccine ChAdOx1 nCoV-19 in 82 healthcare workers more than (n=45) and less than (n=37) 11 months post mild SARS-CoV-2 infection at time of vaccination.FindingsThe post-vaccine levels of RBD-specific IgG and neutralizing antibodies against the SARS-CoV-2 wild type and variants of concern including Delta lineage 1.617.2 were similar or higher in participants receiving a single dose of ChAdOx1 nCoV-19 vaccine post SARS-CoV-2 infection (both more than and less than 11 months post infection) compared to SARS-CoV-2 naïve participants who received two doses of BNT162b2 vaccine.InterpretationOur data support that a single dose ChAdOx1 nCoV-19 vaccine that is administered up to at least 11 months post SARS-CoV-2 infection serves as an effective immune booster. This provides a possible rationale for a single-dose vaccine regimen.FundingA full list of funding bodies that contributed to this study can be found in the Acknowledgements section

Highlights

Recent reports demonstrate robust serological responses to a single dose of messenger RNA vaccines in individuals previously infected with SARS-CoV-2
We show that a single dose of ChAdOx1 nCoV-19 vaccine to previously SARS-CoV-2 infected individuals elicits similar or higher levels of neutralizing antibodies against SARS-CoV-2 wild type and variants of concern, including Delta lineage 1.617.2, as those found following two doses of BNT162b2 vaccine in SARS-CoV-2 naïve individuals
receptor binding domain (RBD)-specific IgG antibodies against the SARS-CoV-2 wild type and variants of concern B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), and B.1.617.2 (Delta)

Summary

Introduction

Recent reports demonstrate robust serological responses to a single dose of messenger RNA (mRNA) vaccines in individuals previously infected with SARS-CoV-2 These individuals develop spike-specific IgG and neutralizing antibody titers after one dose that are equivalent. Methods: We compared RBD-specific IgG and RBD-ACE2 blocking antibodies against SARS-CoV-2 wild type and variants of concern following two doses of the mRNA vaccine BNT162b2 in SARS-CoV-2 naïve healthcare workers (n=65) and a single dose of the adenovector vaccine ChAdOx1 nCoV-19 in 82 healthcare workers more than (n=45) and less than (n=37) 11 months post mild SARS-CoV-2 infection at time of vaccination.

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