Reduced sera neutralization to Omicron SARS-CoV-2 by both inactivated and protein subunit vaccines and the convalescents

Abstract

Omicron variant continues to spread all over the world. There are lots of scientific questions remaining to be answered for such a devastating variant. There are a dozen of vaccines already in clinical use. The very urgent scientific question would be whether or not these vaccines can protect Omicron variant. Here, we tested the sera from both convalescents and vaccine recipients receiving either inactivated or protein subunits vaccines (CoronaVac from Sinovac, or BBIBP-CoV from Sinopharm, or ZF2001 from Zhifei longcom) for the binding antibody titers (ELISA) and neutralization antibodies titers (pseudovirus neutralization assay). We showed that Omicron do have severe immune escape in convalescents, with 15 of 16 were negative in neutralization. By contrast, in vaccinees who received three jabs of inactivated or protein subunit vaccine, the neutralizing activity was much better preserved. Especially in the ZF2001 group with an extended period of the second and third jab (4-6 months) remains 100% positive in Omicron neutralization, with only 3.1-folds reduction in neutralizing antibody (NAb) titer. In this case, we proposed that, the multi-boost strategy with an extended interval between the second and third jab for immune maturation would be beneficial for NAb against devastating variants such as Omicron.

Steep Decline in Binding Capability of SARS-CoV-2 Omicron Variant (B.1.1.529) RBD to the Antibodies in Early COVID-19 Convalescent Sera and Inactivated Vaccine Sera

“…The Omicron variant has a total of 30 mutations on the spike protein, and half of the mutations happened on the RBD compared to the ancestral variant B.1, while there are eight mutations for the Delta variant, two of which exist on the RBD [15]. The results in Figure 2 revealed that the Delta variant, with only two mutations on the RBD, has limited decrease in the binding capability of the RBD to both vaccinated sera and convalescent sera, which was consistent to some studies recently [16,17]. However, Omicron evades antibodies elicited by the ancestral variants and by the inactivated vaccine efficiently, with steep reduction in the binding capability of its RBD.…”

Chimeric mRNA based COVID-19 vaccine induces protective immunity against Omicron and Delta

“…Omicron quickly outcompeted the circulating Delta variant within weeks after landing in Europe and US, and has become the dominant VOC around the globe. Scientists found that there was a significant reduction in Omicron virus neutralizing activity in sera obtained from individuals infected by pre-Omicron variants and populations vaccinated with immunogens based on early WA-1 virus (Cao et al, 2021; Lee et al, 2022; Zhao et al, 2021). A huge number of breakthrough infections have been reported even from individuals fully vaccinated with the 3 rd booster shot.…”

Analysis of SARS-CoV-2 Omicron Neutralization Data up to 2022-01-28

“…GMTs and fold changes were obtained by Webplotdigitzer for Kimpel11 , Corti12 (subset), Gupta13 and Liu14 . The data for Pfizer/BioNTech 15 , Schmidt16 , Israel MoH 17 , HKU18 , Balazs 19 , Gruell20 , Poehlmann21 , Montefiori/Doria-Rose 22 , Ho23 , Schwartz24 , Snape 25 ,Gao26 were directly obtained from the respective manuscripts or reports.…”