key: cord-1048333-kkohr5a3
authors: Luczkowiak, Joanna; Labiod, Nuria; Rivas, Gonzalo; Rolo, Marta; Lasala, Fátima; Lora-Tamayo, Jaime; Mancheno-Losa, Mikel; Rial, David; Pérez-Rivilla, Alfredo; Folgueira, María D; Delgado, Rafael
title: Prime-boost vaccination with BNT162b2 induces high neutralizing activity against SARS-CoV-2 variants in naïve and COVID-19 convalescent individuals
date: 2021-09-24
journal: Open Forum Infect Dis
DOI: 10.1093/ofid/ofab468
sha: 22c23d971856e87e66be5cd51b6f254a742b239a
doc_id: 1048333
cord_uid: kkohr5a3

OBJECTIVES: To investigate the neutralizing response against SARS-CoV-2 Variants of Concern (VoC) during COVID-19 convalescence and after vaccination. METHODS: COVID-19 convalescents and naïve individuals were tested for neutralizing activity against SARS-CoV-2 VoC Alpha, Beta, Gamma and Delta at 1- and 7-months post-infection and 4-6 weeks after BNT162b2 vaccination. RESULTS: Vaccination induced a high neutralizing response in naïve individuals. Interestingly, vaccination of convalescent patients induced a boosting response that was able to neutralize all VoC at high titers. CONCLUSIONS: Vaccination with BNT162b2 induced high levels of neutralization against SARS-CoV-2 VoC in most patients, this is especially beneficial in COVID-19 convalescent individuals.

Circulation of SARS-CoV-2 variants has raised concern since changes in the Spike protein and specially in the RBD sequence are associated with an increased transmissibility and can also determine immune escape to neutralizing antibodies induced by natural infection or vaccination thus jeopardizing pandemic control. Although reinfection with SARS-CoV-2 is relatively uncommon 1 and protection from vaccines based in original sequences has been demonstrated to be high for most candidates 2 , the breadth against infection with Variants of Concern (VoC) in convalescent individuals and vaccinees is largely unknown and requires continuous investigation. We have aimed to investigate the magnitude and breadth of the neutralizing response against the main circulating SARS-CoV-2 VoC during COVID-19 convalescence and after vaccination.

The design of the work has been approved by the local ethical committee: Comité Investigación Clínica Hospital Universitario 12 de Octubre (Reference CEIm 20/157).

A c c e p t e d M a n u s c r i p t

Within the WHO Solidarity II serology network, we have studied the neutralizing response against SARS-CoV-2 in 19 COVID-19 convalescent healthcare workers (HCW) from the Hospital Universitario 12 de Octubre in Madrid, Spain, 17 had an RT-PCR documented SARS-CoV-2 infection and 2 had a positive detection of anti-S IgG upon entry in the study, and an additional group of 17 HCW who were negative for SARS-CoV-2 detection along the follow up. All cases of COVID-19 were either asymptomatic, the two HCW detected only by serology, or with mild to moderate symptoms not requiring oxygen therapy or hospitalization. All infection events took place during the A c c e p t e d M a n u s c r i p t

Results are summarized in Figure 1 . Levels of neutralizing activity against the reference SARS-CoV-2 S sequence (D614G) in the early convalescent period (1 mpi) were heterogeneous as described 10 (NT50 geometric mean (GM) = 1/562). As compared with the reference sequence, sera from convalescents individuals showed a partial decrease of neutralizing activity against variants Alpha, Gamma and Delta at 1 mpi (1.5, 1.9 and 1.6fold respectively) and 7 mpi (1,1 and 1,6-fold) that was more prominent against Beta (6.5 and 2.5-fold reduction at 1 and 7 mpi respectively, both reductions were statistically significant, p<0.01, Figure 1 ). At this time points, 1 and 7 mpi during convalescence, 7 c c e p t e d M a n u s c r i p t phase against the reference sequence) and again, although significantly reduced (2.8fold, p<0.01) as compared with control, neutralizing titer for Beta VoC was considerable (GM NT50 1/1740).

The level of neutralizing antibodies is the main surrogate marker for vaccine efficacy 11 , however in COVID-19 it is currently unknown the correlates for protection for the different vaccines and whether a certain reduction in neutralizing levels can determine a lack of protection against VoC 12 . Also, memory B and T-cell responses are thought to play an important role since severe COVID-19 develops within a time frame that allows their activation and effector functions 13 . Nevertheless, the effective production of neutralizing antibodies requires specific CD4 + T-cells cooperation and the levels of neutralizing response could recapitulate significant functions of both humoral and cellular immunity, furthermore it has been proposed that neutralizing activity could be a reliable marker for vaccine protection 14 . Circulating SARS-CoV-2 VoC present changes in the spike RBD region that allow a higher transmissibility and immune scape through mutations, such as S E484K, in epitopes frequently targeted by neutralizing antibodies 15 . A c c e p t e d M a n u s c r i p t This is clearly evident for SARS-CoV-2 variant Beta since sera from convalescent individuals frequently lacks a measurable neutralizing activity against this VoC as it has been described 16 and our own data ratify (Figure 1) . Immunization with the mRNA vaccine BNT162b2 induced a more homogenous response in naïve individuals than the observed in natural infection and relatively high levels of neutralization against VOC Alpha, Gamma and also against the recent characterized Delta variant. This is particularly important since Delta is rapidly spreading globally and a reduction of neutralizing response by convalescent or vaccinee sera has also been described 17 . We found a modest reduction of NT50 (2.2-fold, p<0.01) in naïve vaccinees against the Delta VoC and all vaccinees had a significant neutralizing level 4-6 weeks after vaccination (GM NT50 1/369). The Beta VoC exhibited the highest reduction in neutralization levels (4.7fold) after vaccination in naïve individuals, although the majority (16/17) had a detectable neutralizing response (GM NT50 1/168). As it has been described, in COVID-19 convalescent individuals vaccination elicited the production of high titers of wide breadth cross-neutralizing antibodies showing high neutralizing levels against VoC 18 . This high neutralizing response includes also the Delta variant (GM NT 1/1907). Whether this is related to the occurrence of affinity maturation of antibodies long after acute infection, as has been recently demonstrated 19, 20 , and vaccination is stimulating the production of a A c c e p t e d M a n u s c r i p t repertoire of antibodies with higher affinity and breadth, remains to be investigated.

Nevertheless, our results support the beneficial effect of vaccination for convalescent patients due to this boosting neutralizing response against VoC. We also found a high neutralizing response after prime-boosting vaccination with BNT162b2 in naïve individuals with a reasonable coverage of SARS-CoV-2 VoC Alpha, Beta, Gamma and Delta at 4-6 weeks after immunization. This neutralizing response against the present or future diversity of SARS-CoV-2 VoC are to be monitored over time. Its evolution could have important implications in our understanding of immune protection and in the development of future strategies for immunization.

SARS-CoV-2 infection rates of antibody-positive compared with antibody-negative health-care workers in England: a large, multicentre, prospective cohort study (SIREN)

Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine

SARS-CoV-2 Spike: Evidence that D614G Increases Infectivity of the COVID-19 Virus

Generation of VSV pseudotypes using recombinant ΔG-VSV for studies on virus entry, identification of entry inhibitors, and immune responses to vaccines

Estimated transmissibility and impact of SARS-CoV-2 lineage B.1.1.7 in England

Detection of a SARS-CoV-2 variant of concern in South Africa

Genomics and epidemiology of the P.1 SARS-CoV-2 lineage in Manaus

SARS-CoV-2 B.1.617 emergence and sensitivity to vaccine-elicited antibodies

Robust neutralizing antibodies to SARS-CoV-2 infection persist for months

Correlates of protection induced by vaccination

A correlate of protection for SARS-CoV-2 vaccines is urgently needed

Adaptive immunity to SARS-CoV-2 and COVID-19

Neutralizing antibody levels are highly predictive of immune protection from symptomatic SARS-CoV-2 infection

Complete Mapping of Mutations to the SARS-CoV-2 Spike Receptor-Binding Domain that Escape Antibody Recognition

Escape of SARS-CoV-2 501Y.V2 from neutralization by convalescent plasma

Reduced sensitivity of SARS-CoV-2 variant Delta to antibody neutralization

Naturally enhanced neutralizing breadth against SARS-CoV-2 one year after infection

Development of potency, breadth and resilience to viral escape mutations in SARS-CoV-2 neutralizing antibodies

A c c e p t e d M a n u s c r i p t A c c e p t e d M a n u s c r i p t

We are greatly thankful to the group of participants health workers for their generous contribution to the study along with the WHO Solidarity2 project for supporting and maintaining a great collaborative network. Research in RD lab is supported by grants 

All the authors declare not having any Conflict of Interest related to this publication A c c e p t e d M a n u s c r i p t Convalescent individuals (n=19) were tested at 1-month post-infection (mpi), 7 mpi, and after BNT162b2 vaccination and a naïve group (n=17) after BNT162b2 vaccination. Individual NT50 dilution values are presented as reciprocals in scatter dot plot. Solid lines correspond to geometric mean. Error bars indicate geometric SD. Dashed lines mark the cut-off titer (NT50=1/66). NT50 was calculated from individual results obtained by triplicates using a nonlinear regression model fit with settings for log inhibitor versus normalized response curves by GraphPad Prism v8. Fold decrease in NT50 as compared to SARS-CoV-2 S D614G together with statistical significance are indicated above scatter dot results for each variant. Statistical analysis was performed by Wilcoxon matched-pairs signed rank test in GraphPad Prism v8. ns=not significant,*p<0.05, **p<0.01, ***p≤0.001.A c c e p t e d M a n u s c r i p t