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While the SARS-CoV-2 vaccine offers 70%-95% protection effectiveness against Coronavirus disease 2019 (COVID-19), a portion of recipients do not produce adequate protective immune responses, particularly, neutralizing antibodies (nAbs). Previous studies of COVID-19 patients have identified several public antibody lineages, such as IGHV3-30, IGHV3-33, IGHV3-53, IGHV1-58, and IGHV1-24. However, it remains unclear how these public antibodies evolve during vaccination or whether there are any special antibody lineages correlated with SARS-CoV-2 vaccination. In this study, through a combination of single B cell sequencing and next-generation sequencing analysis, we systemically studied the dynamic changes of antibody lineages derived from different B cell germlines in their sequence, frequency, and neutralization ability in different vaccinees before and after receiving inactivated SARS-CoV-2 vaccines. Our findings indicate that the frequency of antibodies derived from the IGHV4-34 lineage increased in most individuals after vaccination, and the higher frequency of the antibody usually resulted in stronger binding affinity. Additionally, the ratio of IGHV4-34 derived antibodies, when compared with other public antibodies, more strongly correlated with the neutralization activity of immune sera from vaccinees. Taken together, these results suggest that IGHV4-34 is a novel vaccine-elicited public nAb lineage that plays a crucial role in immune response following inactivated COVID-19 vaccination., (© 2024 Wiley Periodicals LLC.)

Background: Hand, foot, and mouth disease (HFMD) is a highly prevalent and contagious disease, particularly in children under five years old. Its transmission route resembles that of COVID-19. During the COVID-19 pandemic, non-pharmaceutical interventions (NPIs) were implemented to curb viral spread, which may have concurrently reduced HFMD incidence., Methods: Utilizing HFMD surveillance data from the Anhui Provincial Center for Disease Control and Prevention (2015-2020) and varying levels of COVID-19 emergency measures, a Bayesian structural time series model predicted the counterfactual HFMD incidence and quantified the causal relationships with NPIs., Results: During the implementation of NPIs, the 915 cases observed between weeks 4 and 20 of 2020 reflected a 94.9% reduction from the expected cases number (915 vs. 17,790), avoiding approximately 16,875 cases. The relative reduction of male cases (95.2%) was similar to that of female cases (94.3%). Different age groups the number of cases decline roughly similar were 93.1%, 95.3%, 97.8%, 94.9%., Conclusion: During the COVID-19 pandemic, NPIs implemented in response to COVID-19 effectively reduced HFMD incidence. NPIs should be promoted for future control of enteric infectious diseases such as HFMD., Competing Interests: Declarations. Ethics approval and consent to participate: This study was approved by the ethics committee of Anhui Provincial Center for Disease Control and Prevention (No. AHJK2023-B003-02). All individuals provided their written informed consent to participate in this study. The raw data did not contain any personal identifying information that could be linked to a particular individual and were anonymized before its use. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Monitoring variations in the virus genome to understand the SARS-CoV-2 evolution and spread of the virus is extremely important. Seven early SARS-CoV-2 isolates in China were cultured in vitro and were analyzed for their viral infectivity through viral growth assay, tissue culture infectious dose (TCID 50 ) assay, spike protein quantification, and next generation sequencing analysis, and the resultant mutations in spike protein were used to generate the corresponding pseudoviruses for analysis of immune escape from vaccination and postinfection immunity. The results revealed that in vitro cultured SARS-CoV-2 virus had much higher mutation frequency (up to ~20 times) than that in infected patients, suggesting that SARS-CoV-2 diversify under favorable conditions. Monitoring viral mutations is not only helpful for better understanding of virus evolution and virulence change, but also the key to prevent virus transmission and disease progression. Compared with the D614G reference strain, a pseudovirus strain of SARS-CoV-2 was constructed with a high mutation rate site on the spike protein. We found some novel spike mutations during in vitro culture, such as E868Q, conferred further immune escape ability., (© 2023 Wiley Periodicals LLC.)

Background: COVID-19 has spread worldwide and become a pandemic. We report the epidemiological and clinical characteristics of cluster infections., Methods: Data of clustered cases were retrieved from the public health emergency monitoring information system of China. We analyzed the incubation period, generation gap, secondary attack rate, and viral load in various grouped cases., Results: A total of 60 COVID-19 infection clusters including 226 patients and 19 asymptomatic cases involving four generations were analyzed. With the increase of transmission generations, secondary attack rate decreased (P＜0.001) and severity alleviated (P = 0.008). The median incubation period and intergenerational interval were 9 and 6 days, respectively. The secondary attack rate was 7.1% in the index cases, 5.0% in the first generation, 1.0% in the second generation, and 4.7% overall. Severe cases were seen more in the index (13, 65%) and first generation (7, 35%) ones, who had a significantly higher viral load than the mild and moderate ones., Conclusions: With the increase of transmission generation, secondary infection rate and severity decreased. Severe patients had a higher virus load. Patients in the incubation period and asymptomatic carriers were potential infection sources who might play an important role in transmission., (Copyright © 2021. Published by Elsevier Ltd.)

Background: COVID-19 is a newly emerging disease caused by a novel coronavirus (SARS-CoV-2), which spread globally in early 2020. Asymptomatic carriers of the virus contribute to the propagation of this disease, and the existence of asymptomatic infection has caused widespread fear and concern in the control of this pandemic., Methods: In this study, we investigated the origin and transmission route of SARS-CoV-2 in Anhui's two clusters, analyzed the role and infectiousness of asymptomatic patients in disease transmission, and characterized the complete spike gene sequences in the Anhui strains., Results: We conducted an epidemiological investigation of two clusters caused by asymptomatic infections sequenced the spike gene of viruses isolated from 12 patients. All cases of the two clusters we investigated had clear contact histories, both from Wuhan, Hubei province. The viruses isolated from two outbreaks in Anhui were found to show a genetically close link to the virus from Wuhan. In addition, new single nucleotide variations were discovered in the spike gene., Conclusions: Both clusters may have resulted from close contact and droplet-spreading and asymptomatic infections were identified as the initial cause. We also analyzed the infectiousness of asymptomatic cases and the challenges to the current epidemic to provided information for the development of control strategies.

• 10.9% of asymptomatic SARS-CoV-2 carriers subsequently developed symptoms to become confirmed cases. • The transmission efficiency of asymptomatic SARS-CoV-2 carriers was assessed. • The attack rate for asymptomatic carriers was lower than that for confirmed cases. • Close contact screening should be extended to include the incubation period. Few studies have focused on the transmission efficiency of asymptomatic carriers of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Our follow-up study was performed on 147 asymptomatic carriers in Anhui Province. Of these, 50.0% were male, 50.3% were older than 40 years, 43.8% were farmers, and 68.7% were from the north of Anhui Province. 16 of the 147 asymptomatic carriers developed symptoms in the following 14 days of isolated observation, and were subsequently diagnosed as confirmed cases. The possible latent infection period was found to range from 1–5 days before onset, with a median time of 2 days. The second attack rate for the 16 confirmed cases who had transferred from being asymptomatic carriers was 9.7% (23/236 close contacts), while for the 131 asymptomatic carriers the rate was 2.6% (24/914 close contacts), showing a significant difference in second attack rate between the two groups (p ＜0.001). Our study indicated that COVID-19 cases are contagious during the incubation period, and that close contact screening should be extended to include the incubation period. Our results also showed that the transmission efficiency for asymptomatic carriers was lower than that for confirmed case. [ABSTRACT FROM AUTHOR]