key: cord-1002323-umb6jj26
authors: Suntronwong, N.; Kanokudom, S.; Auphimai, C.; Assawakosri, S.; Thongmee, T.; Vichaiwattana, P.; Duangchinda, T.; Chantima, W.; Pakchotanon, P.; Chansaenroj, J.; Puenpa, J.; Nilyanimit, P.; Srimuan, D.; Thatsanatorn, T.; Sudhinaraset, N.; Wanlapakorn, N.; Poovorawan, y.
title: Effects of boosted mRNA and adenoviral-vectored vaccines on immune responses to omicron BA.1 and BA.2 following the heterologous CoronaVac/AZD1222 vaccination
date: 2022-04-28
journal: nan
DOI: 10.1101/2022.04.25.22274294
sha: 5ff1fa6d2b8f13ca392290467bcf979782e435dd
doc_id: 1002323
cord_uid: umb6jj26

Background. The coronavirus 2019 omicron variant has surged rapidly and raises concerns about immune evasion because it harbors mutations even in individuals with complete vaccination. Here, we examine the capability of the booster vaccination to induce neutralizing antibodies (NAbs) against omicron (BA.1 and BA.2) and T-cell responses. Methods. A total of 167 participants primed with heterologous CoronaVac/AZD1222 were enrolled to receive AZD1222, BNT162b2, or mRNA-1273 as a booster dose. Reactogenicity was recorded. Binding antibody, neutralizing antibody (NAb) titers against omicron BA.1 and BA.2, and total interferon gamma (IFN-{gamma}) post-booster responses were measured. Results. A substantial loss in neutralizing potency to omicron variant was found at 4 to 5 months after receiving the heterologous CoronaVac/AZD1222. Following booster vaccination, a significant increase in binding antibodies and neutralizing activities toward delta and omicron variants was observed. Neutralization to omicron BA.1 and BA.2 were comparable, showing the highest titers after boosted mRNA-1273 followed by BNT162b2 and AZD1222. Notably, boosted individuals with mRNA vaccines could induce T cell response. Reactogenicity was mild to moderate without serious adverse events. Conclusions. Our findings highlight that the booster vaccination could overcome immunity wanes and provide adequate NAbs coverage against omicron BA.1 and BA.2.

As of November 2021, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV- subvariant has recently increased in multiple countries and appears to be more transmissible than 84 BA.1 [7] . Previous studies suggest that BA.1 and BA.2 are highly resistant to neutralization by 85 monoclonal antibody therapy and vaccine-induced immunity [8, 9] . 86 Another concern is the waning immunity that occurs over time. A previous study 87

indicates that the IgG antibodies declined a consistent rate at six months after second dose of the 88 mRNA vaccination while neutralizing antibodies declined rapidly over the first three months 89 followed by a relatively slower decrease after that point [10] . A reduction in NAbs is related to 90 an increased risk of symptomatic SARS-CoV-2 infection and reduced vaccine effectiveness [11] . 91 All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint Moreover, omicron variants were poorly or not at all neutralized in the sera sampled five months 92 after completing the two-dose BNT162b2 or AZD1222 vaccination courses [12] . Due to the 93 emergence of omicron and waning immunity, a booster vaccination program has been 94 implemented in many countries [13, 14] . Thus, data on boosting immunity against omicron 95 variant are needed. 96

Besides humoral immunity, cell-mediated immunity also plays an essential role in indicated that mRNA vaccine-or AZD1222-boosted individuals after a two-dose CoronaVac 111 course elicited a higher immune response than in those receiving boosted inactivated vaccines 112

[21]. In the COV-BOOST trial, the heterologous boost after either two-dose of AZD1222 or 113

BNT162b2 prime showed an increased humoral and cell-mediated immune response compared 114 All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Due to the limited vaccine supply, Thailand has administered the heterologous 119

CoronaVac followed by AZD1222 vaccination as an alternative regimen for combatting the delta 120 variant. This regimen could induce a higher immune response than the homologous CoronaVac 

In a cohort study, 167 individuals who had received CoronaVac/AZD1222 vaccination at 133 least 4 to 5 months earlier and with no history of SARS-CoV-2 infection were enrolled. The 134 participants were offered immunization with one of three approved vaccines, including 135 AZD1222, BNT162b2, or mRNA-1273 vaccines. The cohort study started between November 136 30, 2021 and January 24, 2022. The participants received adverse events (AEs) documents to 137 All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. 

The study vaccines used as booster doses included AZD1222 (AstraZeneca, Oxford, UK) 146 30% was defined as positive, indicating the presence of neutralizing antibodies. The lower limit 160 All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint 8 of detection was set as 0% inhibition. 161

Live SARS-CoV-2 neutralizing antibody titers in a subset of serum samples were 163 determined using a 50% focus reduction neutralization test (FRNT50) against omicron BA.1 164 (accession number: EPI_ISL_8547017) and BA.2 (EPI_ISL_11698090) subvariants. Briefly, 165

heat-inactivated sera were used to prepare serial dilutions starting from 1:10 to 1:7,290 and percentage for an individual sample was calculated, and the half-maximal inhibitory 170 concentration (IC50) was evaluated using PROBIT software. If no neutralization was observed, 171 the FRNT50 was set as 10, which is one dilution step below the lower limit of detection (dilution 172 1:20). 173

The SARS-CoV-2-specific T-cell response was evaluated by using a commercially 175 available IFN-γ release assay in whole blood according to the manufacturer's instructions 176 (QuantiFERON, Qiagen, Hilden, Germany). Heparinized whole blood was incubated with 177 different antigens, including negative (Nil), positive (Mitogen) and two different SARS-CoV-2 178 antigens (Ag1 and Ag2). The Ag1 tube was coated with S1subunit (RBD) peptides with CD4+ 179 stimulation, and Ag2 contained S1+S2 peptides for CD4+ and CD8+ stimulation. After 180 stimulation, total IFN-ɣ production was measured as previously described [23] . The results were 181 calculated from a standard curve and expressed as IU/mL after subtraction of the Nil control. The 182 All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint total IFN-ɣ with a value ≥ 0.15 IU/mL and ≥ 25% of Nil were considered a positive response 183 against SARS-CoV-2. 184

Baseline characteristics were expressed as number or percentage and median with 186 interquartile ranges (IQRs). The levels of binding antibody and NAbs were presented as 187 geometric mean titers (GMT). A comparison of log-transformed data was determine using one- (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint not significantly different (Table 1) . Additionally, no statistically significant differences were 206 observed in the time intervals between the first and the second doses for any group. However, the 207 median interval between the second and third dose in AZD1222 (125 days, IQR: 118-134.5) was 208 slightly shorter (but not statistically significant) than BNT162b2 (130 days, IQR: 110-141) and mRNA-1273 individuals although these differences were not significant. On the contrary, the 225 age-related trend was not found in AZD1222-or BNT162b2-boosted individuals ( Figure 1C) . 226

Most boosted individuals were seronegative for anti-N IgG, indicating no SARS-CoV-2 227 All rights reserved. No reuse allowed without permission.

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The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint exposure during the study period ( Figure 1D ). Although one participant had an anti-N IgG level 228 above the cut-off, the anti-RBD IgG level was comparable with other participants at baseline, 229 suggesting the anti-N IgG may be induced by CoronaVac prime vaccination. 230

Neutralizing activity to the delta and omicron variants was measured in sera at baseline 232 and 28 days after post-boost using the surrogate virus neutralization test. All boosted individuals 233 could restore neutralizing activity to delta by more than 90% (Figure 2A ). Although baseline 234 neutralizing activity to omicron declined at 4 to 5 months after the second dose, a 20% (6/30), 235 83% (25/30), and 90% (27/30) of individuals boosted with AZD1222, BNT162b2, and mRNA-236 1273, respectively, were detected to possess omicron variant neutralizing potential ( Figure 2B) . 237

higher level of neutralizing activity than those boosted with AZD1222. The median of 239 neutralizing activity to omicron was 10.1% for AZD1222, 55.9% for BNT162b2, and 78.2% for 240 mRNA-1273 after booster vaccination. Although neutralizing activity against omicron was 241 significantly lower than that against the delta variant, most individuals have detected the 242 neutralizing activity against omicron after receiving booster mRNA vaccines ( Figure 2C ). 243

The functional NAb titers against omicron BA.1 and BA.2 were quantified using a live 245 virus neutralization test (FRNT50). At baseline, 80% (24/30) and 43% (13/30) of vaccinated 246 individuals with heterologous CoronaVac/AZD1222 had NAbs to omicron BA.1 and BA.2, 247 respectively, which dropped below detectable levels ( Figure 3 ). After 28 days post-boost, NAb 248 All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 28, 2022. 

Besides the neutralizing antibodies, the T cell response were assessed by measuring total 263 IFN-γ responses in whole blood from AZD1222-, BNT162b2-, and mRNA-1273-boosted 264 individuals after S1 (RBD) peptides for CD4+ stimulation or Ag1 ( Figure 4A ) and S1+S2 265 peptides for CD4+ and CD8+ stimulation or Ag2 ( Figure 4B ). At baseline, 47% (43/90) and (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint responses after stimulation with the spike protein of the ancestral strain. On the contrary, no 271 difference in IFN-γ response in those boosted with AZD1222 compared to baseline was found. 272

induce a T-cell response, which elicits a higher level of IFN-γ response, but this process was not 274 observed in those boosted with the AZD1222 vaccine. 275

Local and systemic reactogenicity were self-reported within seven days after booster 277 vaccination. A high frequency of adverse events (AEs) was observed within 2 to 3 days 278 following the booster dose and were predominantly mild to moderate (Supplementary Figure 3) . boosted with AZD1222. Although mRNA vaccines showed a higher frequency of AEs than 293 All rights reserved. No reuse allowed without permission.

(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint 14 AZD1222 vaccine, the reactogenicity was in acceptable ranges, indicating a good safety profiles 294 after booster vaccination. 295

It was found that individuals who received the heterologous CoronaVac/AZD1222 296 vaccination exhibited a 5.9-fold reduction in binding antibody and less detectable NAbs to were not found in this study, which might because most participants were less than 60 years old. 305

Neutralizing antibody titers is a highly predict the immune protection against SARS- previously been reported, their coverages were improved through affinity maturation over time 315

and might be sufficient to expand the coverage of neutralization against SARS-CoV-2 variants 316 All rights reserved. No reuse allowed without permission.

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The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint after receiving a booster dose [31] . Furthermore, a reduced neutralizing activity against omicron 317 compared to delta variant was found. Similar results were found concerning neutralizing activity 318 to omicron, which was reduced by 6-to 23-fold lower than delta after booster vaccination [12] . (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint 

Rapid epidemic expansion of the SARS-CoV-2

Omicron variant in southern Africa

SARS-CoV-2 variants, spike mutations and 384 immune escape

Omicron escapes the majority of existing SARS-CoV-2 386 neutralizing antibodies

Striking antibody evasion manifested by the Omicron 388 variant of SARS-CoV-2

Increased risk of SARS-CoV-2 390 reinfection associated with emergence of Omicron in South Africa

Omicron (BA. 1) and Sub-Variants (BA

BA. 2 and BA. 3) of SARS-CoV-2 Spike Infectivity and Pathogenicity: A Comparative 394

Sequence and Structural-based Computational Assessment

Overview of Variants/Mutations

Accessed 16

Efficacy of Antibodies and Antiviral 399 Drugs against Covid-19 Omicron Variant

Efficacy of Antiviral Agents against the 401

Waning immune humoral response to BNT162b2

Covid-19 vaccine over 6 months

Neutralizing antibody levels are highly 405 predictive of immune protection from symptomatic SARS-CoV-2 infection

Considerable escape of SARS-CoV-2 Omicron to 408 antibody neutralization

Safety and immunogenicity of seven COVID-19 412 vaccines as a third dose (booster) following two doses of ChAdOx1 nCov-19 or

BNT162b2 in the UK (COV-BOOST): a blinded, multicentre, randomised, controlled, 414 phase 2 trial

Correlates of protection against SARS-CoV-2 in 416 rhesus macaques

Antigen-specific adaptive immunity to

SARS-CoV-2 in acute COVID-19 and associations with age and disease severity

Divergent SARS CoV-2 Omicron-421

reactive T-and B cell responses in COVID-19 vaccine recipients

T cell responses to SARS-CoV-2 spike cross-424 recognize Omicron

Age in years (mean, IQR) in age between groups using one-way ANOVA. c represents the comparison in dosing 473 interval between groups using Kruskal-Wallis H test

All rights reserved. No reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint All rights reserved. No reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint this version posted April 28, 2022. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint this version posted April 28, 2022. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint this version posted April 28, 2022. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint this version posted April 28, 2022. Serum samples from vaccinated individuals receiving heterologous CoronaVac/AZD1222 519 followed by a third booster with AZD1222 (n = 30, purple), BNT162b2 (n = 30, green), or 520 mRNA-1273 (n = 30, yellow) were stimulated by (A) Ag1, which is a CD4+ epitope derived 521 from RBD, minus negative control (Nil), and (B) Ag2, which is CD4+ and CD8+ epitopes 522 derived from S1 and S2 subunits, minus negative control (Nil). Levels of IFN-γ above cutoff 523 values (0.15 IU/mL and ≥ 25% of Nil) indicate a reactive response. Horizontal bars indicate the 524 median. The cut-off values were represented by horizontal dotted line. Statistical analysis was 525 done using Wilcoxon signed rank test (two-tailed). ns indicates no significant difference; **, p < 526 0.01; ***, p < 0.001. 527 528 All rights reserved. No reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint this version posted April 28, 2022. 

All rights reserved. No reuse allowed without permission.(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint this version posted April 28, 2022. ; https://doi.org/10.1101/2022.04.25.22274294 doi: medRxiv preprint