Project description:BackgroundPrior to this report, variants of concern for SARS-CoV-2 were only detected from imported cases in Hong Kong.ObjectiveMultiple cases of SARS-CoV-2 lineage B.1.351 have been identified in local community. We reported the phylogenetic relationship of these cases.Study designSARS-CoV-2 cases were screened for the key non-synonymous substitutions in spike protein by different assays. Preliminary positive cases were further tested by whole genome sequencing.ResultsFrom Dec 2020 to May 2021, 55 SARS-CoV-2 cases belonged to lineage B.1.351. Among them, eight genomes were clustered together, all of them were local cases with epidemiological link.ConclusionsTo track variants of SARS-CoV-2 and to allow early implementation of control measures, SARS-CoV-2 genomic surveillance must be consistently performed.
Project description:Hong Kong utilized an elimination strategy with intermittent use of public health and social measures and increasingly stringent travel regulations to control SARS-CoV-2 transmission. By analyzing >1700 genome sequences representing 17% of confirmed cases from 23-January-2020 to 26-January-2021, we reveal the effects of fluctuating control measures on the evolution and epidemiology of SARS-CoV-2 lineages in Hong Kong. Despite numerous importations, only three introductions were responsible for 90% of locally-acquired cases, two of which circulated cryptically for weeks while less stringent measures were in place. We found that SARS-CoV-2 within-host diversity was most similar among transmission pairs and epidemiological clusters due to a strong transmission bottleneck through which similar genetic background generates similar within-host diversity. Out of the 170 detected introductions of SARS-CoV-2 in Hong Kong during 2020, three introductions caused 90% of community cases.
Project description:BACKGROUND:The spike glycoprotein (S) gene of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) has been useful in analyzing the molecular epidemiology of the 2003 SARS outbreaks. OBJECTIVES:To characterize complete SARS-CoV S-gene sequences from Hong Kong. STUDY DESIGN:Fifty-six SARS-CoV S-gene sequences, obtained from patients who presented with SARS to the Prince of Wales Hospital during March-May 2003, were analysed using a maximum likelihood (ML) approach, together with 138 other (both human and animal) S-gene sequences downloaded from GenBank. RESULTS:The maximum-likelihood (ML) trees showed little evolution occurring within these 56 sequences. Analysis with the other sequences, showed three distinct SARS clusters, closely correlated to previously defined early, middle and late phases of the 2003 international SARS outbreaks. In addition, two new single nucleotide variations (SNVs), T21615A and T21901A, were discovered, not previously reported elsewhere. CONCLUSIONS:The ML approach to the reconstruction of tree phylogenies is known to be superior to the more popular, less computationally and time-demanding neighbour-joining (NJ) approach. The ML analysis in this study confirms the previously reported SARS epidemiology analysed mostly using the NJ approach. The two new SNVs reported here are most likely due to the tissue-culture passaging of the clinical samples.
Project description:We detected severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA on disposable wooden chopsticks used by 5 consecutive asymptomatic and postsymptomatic patients admitted for isolation and care at our hospital. Although we did not assess virus viability, our findings may suggest potential for transmission through shared eating utensils.
Project description:We sequenced severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes from deep throat saliva samples of three imported cases in Hong Kong by Nanopore sequencing. Epidemiological and clinical features of these coronavirus disease 2019 (COVID-19) cases were presented for genomic epidemiology studies.
Project description:We sequenced 10% of imported severe acute respiratory syndrome coronavirus 2 infections detected in travelers to Hong Kong and revealed the genomic diversity of regions of origin, including lineages not previously reported from those countries. Our results suggest that international or regional travel hubs might be useful surveillance sites to monitor sequence diversity.
Project description: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.
Project description:Hong Kong experienced a surge of Omicron BA.2 infections in early 2022, resulting in one of the highest per-capita death rates of COVID-19. The outbreak occurred in a dense population with low immunity towards natural SARS-CoV-2 infection, high vaccine hesitancy in vulnerable populations, comprehensive disease surveillance and the capacity for stringent public health and social measures (PHSMs). By analyzing genome sequences and epidemiological data, we reconstructed the epidemic trajectory of BA.2 wave and found that the initial BA.2 community transmission emerged from cross-infection within hotel quarantine. The rapid implementation of PHSMs suppressed early epidemic growth but the effective reproduction number (Re) increased again during the Spring festival in early February and remained around 1 until early April. Independent estimates of point prevalence and incidence using phylodynamics also showed extensive superspreading at this time, which likely contributed to the rapid expansion of the epidemic. Discordant inferences based on genomic and epidemiological data underscore the need for research to improve near real-time epidemic growth estimates by combining multiple disparate data sources to better inform outbreak response policy.
Project description:Hong Kong employed a strategy of intermittent public health and social measures alongside increasingly stringent travel regulations to eliminate domestic SARS-CoV-2 transmission. By analyzing 1899 genome sequences (>18% of confirmed cases) from 23-January-2020 to 26-January-2021, we reveal the effects of fluctuating control measures on the evolution and epidemiology of SARS-CoV-2 lineages in Hong Kong. Despite numerous importations, only three introductions were responsible for 90% of locally-acquired cases. Community outbreaks were caused by novel introductions rather than a resurgence of circulating strains. Thus, local outbreak prevention requires strong border control and community surveillance, especially during periods of less stringent social restriction. Non-adherence to prolonged preventative measures may explain sustained local transmission observed during wave four in late 2020 and early 2021. We also found that, due to a tight transmission bottleneck, transmission of low-frequency single nucleotide variants between hosts is rare.