Low neutralization of SARS-CoV-2 Omicron BA.2.75.2, BQ.1.1, and XBB.1 by parental mRNA vaccine or a BA.5-bivalent booster.

The newly emerged SARS-CoV-2 Omicron sublineages, including the BA.2-derived BA.2.75.2 and the BA.5-derived BQ.1.1 and XBB.1, have accumulated additional spike mutations that may affect vaccine effectiveness. Here we report neutralizing activities of three human serum panels collected from individuals 23-94 days after dose 4 of a parental mRNA vaccine, 14-32 days after a BA.5-bivalent-booster from individuals with 2-4 previous doses of parental mRNA vaccine, or 15-32 days after a BA.5-bivalent-booster from individuals with previous SARS-CoV-2 infection and 2-4 doses of parental mRNA vaccine. The results showed that a BA.5-bivalent-booster elicited a high neutralizing titer against BA.4/5 measured at 14- to 32-day post-boost; however, the BA.5-bivalent-booster did not produce robust neutralization against the newly emerged BA.2.75.2, BQ.1.1, or XBB.1. Previous infection significantly enhanced the magnitude and breadth of BA.5-bivalent-booster-elicited neutralization. Our data support a vaccine update strategy that future boosters should match newly emerged circulating SARS-CoV-2 variants.

Neutralization of SARS-CoV-2 Omicron sublineages by 4 doses of the original mRNA vaccine.

Since the initial emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.1, several Omicron sublineages have emerged, leading to BA.5 as the current dominant sublineage. Here, we report the neutralization of different Omicron sublineages by human sera collected from individuals who had distinct mRNA vaccination and/or BA.1 infection. Four-dose-vaccine sera neutralize the original USA-WA1/2020, Omicron BA.1, BA.2, BA.2.12.1, BA.3, and BA.4/5 viruses with geometric mean titers (GMTs) of 1,554, 357, 236, 236, 165, and 95, respectively; two-dose-vaccine-plus-BA.1-infection sera exhibit GMTs of 2,114, 1,705, 730, 961, 813, and 274, respectively; and three-dose-vaccine-plus-BA.1-infection sera show GMTs of 2,962, 2,038, 983, 1,190, 1,019, and 297, respectively. Thus, the four-dose vaccine elicits the lowest neutralization against BA.5; the two-dose vaccine plus BA.1 infection elicits significantly higher GMTs against Omicron sublineages than the four-dose-vaccine; and the three-dose vaccine plus BA.1 infection elicits slightly higher GMTs (statistically insignificant) than the two-dose vaccine plus BA.1 infection. Finally, the BA.2.75 is more susceptible than BA.5 to four-dose-vaccine-elicited neutralization and three-dose-vaccine-plus-BA.1-infection-elicited neutralization.

Research on Children’s Aesthetic Needs of Multinational Children’s Songs Based on Information Security

In the context of information security, the aesthetics and data privacy security of multinational children’s songs are studied. The research collects the data of foreign children’s songs, and on the basis of the collected data, the mathematical model of the children’s song text is constructed by using a random matrix. An industry consisting of various media entities that disseminate information is analyzed. In addition, vocal performance is used to improve children’s aesthetic ability and comprehensive quality. An efficient information hiding scheme based on the random matrix is proposed. Furthermore, by establishing a random matrix to optimize the information scheme hidden in the multinational children’s songs, the textual expression efficiency of children’s songs is improved. The results reveal that when the model is iterated for 200 times, the traditional algorithm has only a recognition accuracy of 0.73 for children’s songs, and the recognition accuracy of the convolution neural network (CNN) model can reach 0.76, while the proposed improved deep neural networks (DNN) algorithm model has the best recognition accuracy, which can reach 0.80. It explores how to better meet children’s aesthetic and cultural needs from the perspective of information security by optimizing the semantic indexing algorithm of random matrix mapping elements. Through the performance test of the algorithm, on account of reducing the time complexity of the algorithm, the classification accuracy of children’s song text can be effectively improved. This exploration has practical reference value for cultivating children’s comprehensive quality and aesthetic ability.

Neutralization Titers in Vaccinated Patients with SARS-CoV-2 Delta Breakthrough Infections.

The continuous emergence of SARS-CoV-2 variants with increased transmission and immune evasion has caused breakthrough infections in the vaccinated population. It is important to determine the threshold of neutralizing antibody titers (NT50) that permit breakthrough infections in humans. Here, we tested the neutralization titers of vaccinated patients who contracted Delta variant. All 64 patients with Delta breakthrough infections exhibited NT50 of less than 70. When the breakthrough sera were tested against USA-WA1/2020 (a strain isolated in late January 2020), 82.8%, 15.6%, and 1.6% of them had the NT50 ranges of <20, 20 to 50, and 50 to 69, respectively. When the same breakthrough sera were tested against Delta-spike SARS-CoV-2, 68.7%, 26.6%, and 4.7% of them had the NT50 ranges of <20, 20 to 50, and 50 to 69, respectively. Overall, the results suggest NT50 of 70 as a potential neutralizing threshold required to prevent Delta breakthrough infections. These clinical laboratory results have implications in vaccine strategy and public health policy. IMPORTANCE Given that neutralizing antibodies play a key role in protection of SARS-CoV-2 infection, it is important to define the neutralization levels in vaccinated individuals when they contracted breakthrough infections. In this study, we analyzed the neutralization levels from 64 vaccinated patients on days 0 to 5 before they tested positive for Delta breakthrough infections. The neutralization titers in these vaccinated individuals were all lower than 70 when they contracted breakthrough infections. The results suggest a neutralization titer of 70 as the potential threshold required to prevent breakthrough infections of Delta variant.

Neutralization of Omicron sublineages and Deltacron SARS-CoV-2 by three doses of BNT162b2 vaccine or BA.1 infection.

Distinct SARS-CoV-2 Omicron sublineages have evolved showing increased fitness and immune evasion than the original Omicron variant BA.1. Here, we report the neutralization activity of sera from BNT162b2 vaccinated individuals or unimmunized Omicron BA.1-infected individuals against Omicron sublineages and "Deltacron" variant (XD). BNT162b2 post-dose 3 immune sera neutralized USA-WA1/2020, Omicron BA.1-, BA.2-, BA.2.12.1-, BA.3-, BA.4/5-, and XD-spike SARS-CoV-2s with geometric mean titres (GMTs) of 1335, 393, 298, 315, 216, 103, and 301, respectively; thus, BA.4/5 SARS-CoV-2 spike variant showed the highest propensity to evade vaccine neutralization compared to the original Omicron variants BA.1. BA.1-convalescent sera neutralized USA-WA1/2020, BA.1-, BA.2-, BA.2.12.1-, BA.3-, BA.4/5-, and Deltacron-spike SARS-CoV-2s with GMTs of 15, 430, 110, 109, 102, 25, and 284, respectively. The unique mutation F486V in the BA.4/5 spike contributes to the increased evasion of antibody neutralization by sublineage BA.4/5. The low neutralization titres of vaccinated sera or convalescent sera from BA.1 infected individuals against the emerging and rapidly spreading Omicron BA.4/5 variants provide important results for consideration in the selection of an updated vaccine in the current Omicron wave.Trial registration: ClinicalTrials.gov; identifier: NCT04368728.

Cross-neutralization of Omicron BA.1 against BA.2 and BA.3 SARS-CoV-2.

The Omicron SARS-CoV-2 has several distinct sublineages, among which sublineage BA.1 is responsible for the initial Omicron surge and is now being replaced by BA.2 worldwide, whereas BA.3 is currently at a low frequency. The ongoing BA.1-to-BA.2 replacement underscores the importance to understand the cross-neutralization among the three Omicron sublineages. Here we test the neutralization of BA.1-infected human sera against BA.2, BA.3, and USA/WA1-2020 (a strain isolated in late January 2020). The BA.1-infected sera neutralize BA.1, BA.2, BA.3, and USA/WA1-2020 SARS-CoV-2s with geometric mean titers (GMTs) of 445, 107, 102, and 16, respectively. Thus, the neutralizing GMTs against heterologous BA.2, BA.3, and USA/WA1-2020 are 4.2-, 4.4-, and 28.4-fold lower than the GMT against homologous BA.1, respectively. These findings have implications in COVID-19 vaccine strategy.