Neutralization against emerging Omicron subvariants after SARS-CoV-2 reinfection

Dear Editor, In this journal, Wang and colleagues reported some of the clinical features amongst patients as Omicron began to circulate amongst the population of China1Wang B. Yu Y. Yu Y. et al.Clinical features and outcomes of hospitalized patients with COVID-19 during the Omicron wave in Shanghai, China.J Infect. 2023; 86: e27-e29Abstract Full Text Full Text PDF PubMed Scopus (0) Google Scholar. Next, between December 2022 and February 2023, over 80% of the population in China were infected by Omicron BA.5 subvariants (BA.5.2 and BF.7) after adjustment of the zero-COVID-19 policy2Fu D. He G. Li H. et al.Effectiveness of COVID-19 Vaccination Against SARS-CoV-2 Omicron Variant Infection and Symptoms - China, December 2022-February 2023.China CDC Wkly. 2023; 5: 369-373Crossref PubMed Scopus (4) Google Scholar. At present, BA.2.75.2, CH.1.1, and various XBB subvariants are co-circulating in the world, in which the XBB subvariants have become predominant3WHO . Weekly epidemiological update on COVID-19 - 15 June 2023 . Available at: 〈https://www.who.int/publications/m/item/weekly-epidemiological-update-on-covid-19---15-june-2023〉. Accessed June 19th.Google Scholar. Neutralizing activity elicited by vaccination or infection against emerging Omicron subvariants has been well reported previously4Davis-Gardner M.E. Lai L. Wali B. et al.Neutralization against BA.2.75.2, BQ.1.1, and XBB from mRNA Bivalent Booster.N Engl J Med. 2023; 388: 183-185Crossref PubMed Scopus (58) Google Scholar, 5Yue C. Song W. Wang L. et al.ACE2 binding and antibody evasion in enhanced transmissibility of XBB.1.5.Lancet Infect Dis. 2023; 23: 278-280Abstract Full Text Full Text PDF PubMed Google Scholar, 6Chen J.J. Li L.B. Peng H.H. et al.Neutralization against XBB.1 and XBB.1.5 after omicron subvariants breakthrough infection or reinfection.Lancet Reg Health West Pac. 2023; 33100759Google Scholar, while studies on humoral immunity after reinfection have been limited7Chen X. Xu Y. Xie Y. et al.Protective effect of plasma neutralization from prior SARS-CoV-2 Omicron infection against BA.5 subvariant symptomatic reinfection.Lancet Reg Health West Pac. 2023; 33100758Google Scholar. Therefore, we enrolled participants in three groups who were previously vaccinated with inactivated vaccine (BBIBP-CorV or CoronaVac) or recombinant protein vaccine (ZF2001) without infection, in one group who suffered BA.5 primary infection, in five groups who suffered BA.5 reinfection with Wild-type (WT), Gamma, BA.1.1, BA.2.2, or BA.2.76 primary infection, and in one group who suffered XBB reinfection with BA.5 primary infection (Supplementary Table S1-S12). We then measured the neutralizing antibody (NAb) titers of serum samples from these participants against the D614G strain and Omicron subvariants BA.2, BA.4/5, BF.7, BQ.1.1, BA.2.75.2, CH.1.1, XBB.1.5, XBB.1.16, and EG.5.1 using pseudovirus neutralization tests (pVNT) (Supplementary Figure S1A). We first assessed the neutralizing ability of serum from participants in the previously vaccinated groups (Fig. 1A-C). In the group vaccinated with the 2 doses inactivated vaccine, we found that 73.3% of the serum was able to neutralize D614G, while all serum lost its ability to neutralize the Omicron subvariants (Fig. 1A). In the group vaccinated with the 3 doses inactivated vaccine, 86.7% and 20.0% of serum showed detectable NAbs against D614G and BA.2, respectively, but all samples failed to neutralize the other Omicron subvariants (Fig. 1B). For subjects vaccinated with 3-dose of ZF2001, 100%, 73.3%, 20.0% and 20.0% serum neutralized D614G, BA.2, BA.4/5 and BF.7, respectively, and the NAb titers against the Omicron subvariants were significantly lower than those against D614G (Fig. 1C). However, serum from subjects vaccinated with 3-dose of ZF2001 also lost its ability to neutralize BQ.1.1, BA.2.75.2, CH.1.1, XBB.1.5, XBB.1.6, and EG.5.1 (Fig. 1C). Next, we assessed the neutralizing ability in participants who had only suffered from Omicron BA.5 primary infection (Fig. 1D). The NAb titers were 1.4 to 2.6 times lower against BA.2, BA.4/5 and BF.7 than against D614G, while they were 17.4 to 91.9 times lower against the other Omicron subvariants. What’s more, significantly lower NAb titers were observed for BQ.1.1, BA.2.75.2, CH.1.1, XBB.1.5, XBB.1.16, and EG.5.1 compared to D614G, BA.2, BA.4/5, and BF.7. We then measured the NAb titers of serum from participants who had been reinfected with Omicron BA.5 in five groups. Overall, the serum NAb titers were comparable to those against D614G for Omicron BA.2, BA.4/5, and BF.7, while those against BQ.1.1, BA.2.75.2, CH.1.1, XBB.1.5, XBB.1.16, and EG.5.1 were significantly lower than those against D614G (Fig. 1E-I). For subjects with WT primary infection, the NAb titers were 0.9 to 1.9 times lower against BA.2, BA.4/5, and BF.7 than against D614G, while they were 15.5 to 95.0 times significantly lower against the other Omicron subvariants (Fig. 1E). For subjects with Gamma primary infection, the NAb titers were 0.9 to 1.8 times lower against BA.2, BA.4/5, and BF.7 than against D614G, while they were 11.1 to 78.2 times lower against other Omicron subvariants (Fig. 1F). For subjects with BA.1.1 primary infection, the NAb titers were 0.7 to 0.9 times lower against BA.2, BA.4/5, and BF.7 than against D614G, and they were 3.4 to 20.0 times significantly lower against the other Omicron subvariants (Fig. 1G). When subjects suffered BA.2.2 primary infection, the NAb titers were 0.7 to 1.1 times lower against BA.2, BA.4/5, and BF.7 than against D614G, while they were 5.4 to 16.3 times significantly lower against the other Omicron subvariants (Fig. 1H). Finally, for participants with BA.2.76 primary infection, the NAb titers against BA.2, BA.4/5, and BF.7 were 1.5 to 3.1 times lower than that those against D614G, however, a significant reduction of 18.1 to 113.0 times was observed against the other six Omicron subvariants compared to D614G (Fig. 1I). Finally, we measured the NAb titers of serum from participants who had been reinfected with Omicron XBB and found that the serum had detectable NAb titers against all SARS-CoV-2 variants (Fig. 1J). The NAb titers were 1.2 to 1.5 times lower against BA.2, BA.4/5, and BF.7 than against D614G, while they were 3.0 to 3.2 times slightly lower against BQ.1.1 and EG.5.1, and were 4.7 to 9.5 times significantly lower against the other four Omicron subvariants. A further comparison between the different groups showed that participants vaccinated with 3 doses of ZF2001, SARS-CoV-2 primary infection or reinfection had significantly higher NAb titers against D614G than participants vaccinated with 2–3 doses of inactivated vaccine (Supplementary Figure S2A). For the Omicron BA.2, BA.4/5, BF.7, BQ.1.1, BA.2.75.2, XBB.1.16, and EG.5.1 subvariants, significantly higher NAb titers were observed in each SARS-CoV-2 primary or reinfected group than in the previously vaccinated groups (Supplementary Figure S2B-F, I, and J). For CH.1.1, the NAb titers in Omicron-Omicron subvariants reinfection groups were significantly higher than in previously vaccinated groups (Supplementary Figure S2G). For XBB.1.5, all of the SARS-CoV-2 reinfected groups had significantly higher NAb titers than those in the previously vaccinated groups (Supplementary Figure S2H). What’s more, SARS-CoV-2 reinfection group had higher NAb titers against all Omicron subvariants than the BA.5 primary infection group, especially for those Omicron-Omicron reinfection groups (Supplementary Figure S2B-J), and the results were furtherly confirmed by the antigenic map, in which Omicron BA.5 or XBB reinfection can shorten the antigen distance between group A (D614G, BA.2, BA.4/5, and BF.7) and group B (BQ.1.1, BA.2.75.2, CH.1.1, XBB.1.5, XBB.1.16, and EG.5.1) (Fig. 1K-M). In addition, comparisons between the reinfection groups showed that the BA.1.1 or BA.2.2 primary infection group had significantly higher NAb titers against BA.2.75.2, CH.1.1, XBB.1.16, and EG.5.1 than the WT, Gamma, or BA.2.76 primary infection group (Supplementary Figure S2F, G, I, and J). Moreover, XBB reinfection group had significantly higher NAb titers against BQ.1.1, BA.2.75.2, CH.1.1, XBB.1.5, XBB.1.16, and EG.5.1 than the WT, Gamma, or BA.2.76 primary infection group (Supplementary Figure S2E-J). Consistent with previous studies8Cao Y. Jian F. Wang J. et al.Imprinted SARS-CoV-2 humoral immunity induces convergent Omicron RBD evolution.Nature. 2023; 614: 521-529PubMed Google Scholar, 9Qu P. Faraone J.N. Evans J.P. et al.Enhanced evasion of neutralizing antibody response by Omicron XBB.1.5, CH.1.1, and CA.3.1 variants.Cell Rep. 2023; 42112443Abstract Full Text Full Text PDF Scopus (9) Google Scholar, the comparison of amino acid mutation sites in the RBD region suggests that mutations of G339H, G446S, N460K, and F486S/P play an important role in neutralization resistance against BQ.1.1, BA.2.75.2, CH.1.1, XBB.1.5, XBB.1.16, and EG.5.1 (Supplementary Figure S1B), and that the development of the next generation of COVID-19 vaccines should cover as many of the above mutation sites as possible. More importantly, as previously reported10Yisimayi A. , Song W. , Wang J. , et al. Repeated Omicron infection alleviates SARS-CoV-2 immune imprinting. 2023 : 2023.05.01.538516.Google Scholar, SARS-CoV-2 reinfection may also alleviate WT-vaccination-induced immune imprinting and induce higher NAb titers against BQ.1.1, BA.2.75.2, CH.1.1, XBB.1.5, XBB.1.16, and EG.5.1 than BA.5 primary infection. Besides, the short time interval between antigen exposures may have reduced the NAb titers against BA.2.75, CH.1.1, XBB.1.5, XBB.1.16, and EG.5.1 in the BA.5 reinfection group with BA.2.76 primary infection11Zhao X. Li D. Ruan W. et al.Effects of a Prolonged Booster Interval on Neutralization of Omicron Variant.N Engl J Med. 2022; 386: 894-896Crossref PubMed Scopus (62) Google Scholar. There is one limitation of our study. Due to the small number of SARS-CoV-2 reinfection subjects enrolled, the factors of sex, age and vaccination background were not fully matched across the different reinfection groups. Nevertheless, this study can still shed important light on SARS-CoV-2 repeated infection. In conclusion, our data suggest that the Omicron subvariants BQ.1.1, BA.2.75.2, CH.1.1, XBB.1.5, XBB.1.16, and EG.5.1 can extensively escape the serum neutralization elicited by SARS-CoV-2 primary infection or reinfection. Considering the decrease of neutralizing antibodies after hybrid immunity and the continued emergence of new variants, humans will be infected multiple times by SARS-CoV-2 in the near future. Therefore, enhanced surveillance of novel variants, assessment of immune escape ability, and development of anti-SARS-CoV-2 updated vaccines or drugs are important in the long run. GLW, YHW, ZQK, and LQF designed and supervised the study. TL, XLL, XL-Li and KGD collected clinical samples and data. ST, XJZ, and KGD performed the laboratory detection. ST, XJZ and GLW analyzed the data. GLW, YHW, LQF, TL and ZQK drafted the manuscript. All authors reviewed and approved the final manuscript. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. We thank all study participants for providing serum and data for this study. This work was supported by Beijing Natural Science Foundation (L222119 to Guo-Lin Wang), the National Natural Science Foundation of China (82103901 to Guo-Lin Wang), the National Key Research and Development Program of China (2019YFC1200502 to Guo-Lin Wang and 2019YFC1200604 to Li-Qun Fang), and the Shandong Natural Science Foundation (ZR2022MH309 to Zeng-Qiang Kou and ZR2021MH372 to Ti Liu). The authors declare no competing interests. Download .docx (121.54 MB) Help with docx files Supplementary material