ABSTRACT
COVID-19 vaccines against the earlier strains of SARS-CoV-2 are now available. However, breakthrough infections can still occur due to waning antibodies and immune escape by new variants. We assessed humoral immune responses to the mRNA (BNT162b2) and inactivated (CoronaVac) vaccines in our healthcare worker cohort (HCW). We recruited HCWs from public and private healthcare institutions across Hong Kong and collected blood samples at enrolment and every 6 months from June 2020 to June 2022. A subset of volunteers provided blood samples between 10 – 42 days after each dose of vaccine. Immune responses to vaccination were measured as SARS-CoV-2 binding antibodies detected by an enzyme-linked immunosorbent assay (ELISA) and SARS-CoV-2 neutralising antibodies by surrogate virus neutralization test (sVNT) and plaque reduction neutralization test (PRNT). Among the 1,736 HCWs enrolled in our cohort, 252 HCWs provided pre- and post-vaccination blood samples after each dose of either vaccine. Two doses of BNT162b2 generated levels of neutralizing antibodies (sVNT inhibition = 96.8%, range = 42.8%, 98.2%) comparable to those generated by natural infections in the first wave (sVNT inhibition = 84.0%, range = 32.9%, 93.8%). Similar levels were achieved with three doses of CoronaVac (sVNT inhibition = 95.3%, range = 64.7%, 98.3%) and heterologous vaccination with two doses of CoronaVac followed by a booster dose of BNT162b2 vaccine (sVNT inhibition = 97.0%, range = 85.8%, 97.7%). These antibody levels waned faster after second doses and slower after third doses for both vaccines. The BNT162b2 vaccine and CoronaVac vaccines can generate robust antibody responses comparable to natural infections. Three doses of the CoronaVac vaccine, or a heterologous boost with the BNT162b2 vaccine following two doses of the CoronaVac vaccine are required to achieve similar levels of neutralising antibodies in vaccinees who received two doses of the BNT162b2 vaccine. [ FROM AUTHOR] Copyright of International Journal of Infectious Diseases is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)
ABSTRACT
To investigate a superspreading event at a fitness center in Hong Kong, China, we used genomic sequencing to analyze 102 reverse transcription PCR-confirmed cases of severe acute respiratory syndrome coronavirus 2 infection. Our finding highlights the risk for virus transmission in confined spaces with poor ventilation and limited public health interventions.
ABSTRACT
Coronavirus disease 2019 (COVID-19) is a global health concern as it continues to spread within China and beyond. The causative agent of this disease, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), belongs to the genus Betacoronavirus, which also includes severe acute respiratory syndrome-related coronavirus (SARSr-CoV) and Middle East respiratory syndrome-related coronavirus (MERSr-CoV). Codon usage of viral genes are believed to be subjected to different selection pressures in different host environments. Previous studies on codon usage of influenza A viruses helped identify viral host origins and evolution trends, however, similar studies on coronaviruses are lacking. In this study, we compared the codon usage bias using global correspondence analysis (CA), within-group CA and between-group CA. We found that the bat RaTG13 virus best matched the overall codon usage pattern of SARS-CoV-2 in orf1ab, spike and nucleocapsid genes, while the pangolin P1E virus had a more similar codon usage in membrane gene. The amino acid usage pattern of SARS-CoV-2 was generally found similar to bat and human SARSr-CoVs. However, we found greater synonymous codon usage differences between SARS-CoV-2 and its phylogenetic relatives on spike and membrane genes, suggesting these two genes of SARS-CoV-2 are subjected to different evolutionary pressures.
ABSTRACT
Coronaviruses (CoVs) are enveloped, single stranded, positive-sense RNA viruses with a large genomic size of 26–32 kilobases. The first human CoV identified in the 1960s was isolated from patients presenting with common cold symptoms. Subsequent epidemic outbreaks of novel zoonotic CoV transmission were reported, examples including HCoV-229E (229E), HCoV-OC43 (OC43), severe acute respiratory syndrome, and Middle East respiratory syndrome (MERS). The ongoing outbreak of MERS in the Middle East is originating from a zoonotic source of dromedary camels. Surveillance later revealed that three CoV species—HCoV-229E (229E), camel-HKU23, and MERS-CoV—were co-circulating in Saudi Arabia dromedary camels. Camel-HKU23 belongs to Group 2a CoV, which also includes human coronavirus OC43, bovine coronavirus, and porcine hemagglutinating encephalomyelitis virus. Recombination, resulting in the generation of different novel genotypes, has been reported previously among these CoVs. Our surveillance of dromedary camels slaughtered in a major abattoir in Nigeria identified camel-HKU23 from nasal swab samples with a prevalence of 2.2 per cent. Phylogenetic analysis showed Nigeria camel-HKU23 is distinct from those previously identified in Saudi Arabia, while still genetically similar, as they share a monophyletic origin. Recombination analysis of Nigeria camel-HKU23 revealed two recombination breakpoints at positions of 22774–24100 base pairs (bp) and 28224–29362 bp. Recombination breakpoint at position 22774, encoding the Group 2a CoV-specific hemagglutinin esterase gene, exhibited high bootstrap support for clustering with RbCoV HKU14, which was previously detected in domestic rabbits in China. The recombination signal is only observed in Nigeria camel-HKU23, suggesting a regional varied evolutionary history of camel-HKU23. Our findings extended the knowledge of the evolutionary relationship among Group 2a CoVs. Further surveillance in other African camels will be important to elucidate the evolution of camel-HKU23. FAU - So, R T Y
ABSTRACT
Objectives: There have been recurrent spillovers from dromedaries into the human population since the emergence of Middle East respiratory syndrome coronavirus (MERS-CoV). All known zoonotic MERS disease had hitherto occurred in the Arabian Peninsula, with none reported in Africa. This study assesses zoonotic MERS-CoV infection in high-risk groups in Morocco. Method(s): The study adapted a World Health Organization (WHO) MERS-CoV protocol to assess the seroprevalence of MERS-CoV and the risk factors of infection among high-risk populations in three study sites in the south of Morocco with high-densities of dromedaries. Demographic and camel exposure data was obtained using a questionnaire for three set study groups - members of the general population, slaughterhouse workers, and camel herders. Human sera samples were tested for MERS-CoV IgG antibodies through ELISA, pseudoparticule neutralisation, and plaque reduction neutralisation assay. Result(s): Blood samples from 479 participants enrolled in the study were collected between November 2017 and January 2018. The results produced the first evidence in Africa of human primary cases of MERS-CoV infection with documented direct exposure to dromedaries. Three out of 137 slaughterhouse workers and one of 186 from the general population group showed the neutralizing MERS-CoV antibody. Conclusion(s): This is the first time MERS-CoV transmission risk factors have been examined in Morocco through a seroprevalence study among high-risk populations. It provided evidence of zoonotic transmission, underlining the need for exhaustive investigations of human ARI in likely areas for evidence of MERS circulation.