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Background: We explored whether hospital‐based surveillance is useful in detecting severe acute respiratory infection (SARI) clusters and how often these events result in outbreak investigation and community mitigation. Methods: During May 2009–December 2020, physicians at 14 sentinel hospitals prospectively identified SARI clusters (i.e., ≥2 SARI cases who developed symptoms ≤10 days of each other and lived <30 min walk or <3 km from each other). Oropharyngeal and nasopharyngeal swabs were tested for influenza and other respiratory viruses by real‐time reverse transcriptase‐polymerase chain reaction (rRT‐PCR). We describe the demographic of persons within clusters, laboratory results, and outbreak investigations. Results: Field staff identified 464 clusters comprising 1427 SARI cases (range 0–13 clusters per month). Sixty percent of clusters had three, 23% had two, and 17% had ≥4 cases. Their median age was 2 years (inter‐quartile range [IQR] 0.4–25) and 63% were male. Laboratory results were available for the 464 clusters with a median of 9 days (IQR = 6–13 days) after cluster identification. Less than one in five clusters had cases that tested positive for the same virus: respiratory syncytial virus (RSV) in 58 (13%), influenza viruses in 24 (5%), human metapneumovirus (HMPV) in five (1%), human parainfluenza virus (HPIV) in three (0.6%), adenovirus in two (0.4%). While 102/464 (22%) had poultry exposure, none tested positive for influenza A (H5N1) or A (H7N9). None of the 464 clusters led to field deployments for outbreak response. Conclusions: For 11 years, none of the hundreds of identified clusters led to an emergency response. The value of this event‐based surveillance might be improved by seeking larger clusters, with stronger epidemiologic ties or decedents. [ABSTRACT FROM AUTHOR]

Background: Measures for mitigation of Coronavirus Disease 2019 (COVID‐19) were set to reduce the spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS‐CoV‐2). SARS‐CoV‐2 and other respiratory viruses share similar transmission routes and some common clinical manifestations. Co‐circulation of SARS‐CoV‐2 and other common respiratory viruses is imminent. Therefore, development of multiplex assays for detecting these respiratory viruses is essential for being prepared for future outbreaks of respiratory viruses. Methods: A panel of three reverse transcription droplet digital PCR (RT‐ddPCR) assays were developed to detect 15 different human respiratory viruses. Evaluations of its performance were demonstrated. A total of 100 local and 98 imported COVID‐19 cases in Hong Kong were screened for co‐infection with other common respiratory viruses. Results: All detected viral targets showed distinct signal clusters using the multiplex RT‐ddPCR assays. These assays have a broad range of linearity and good intra‐/inter‐assay reproducibility for each target. The lower limits of quantification for all targets were ≤46 copies per reaction. Six imported cases of COVID‐19 were found to be co‐infected with other respiratory viruses, whereas no local case of co‐infection was observed. Conclusions: The multiplex RT‐ddPCR assays were demonstrated to be useful for screening of respiratory virus co‐infections. The strict preventive measures applied in Hong Kong may be effective in limiting the circulation of other human respiratory viruses. The multiplex assays developed in this study can achieve a robust detection method for clinical and research purposes. [ABSTRACT FROM AUTHOR]

In response to unusual crow die‐offs from avian influenza A(H5N1) virus infection during January‐February 2017 in Dhaka, Bangladesh, a One Health team assessed potential infection risks in live bird markets (LBMs). Evidence of aerosolized avian influenza A viruses was detected in LBMs and in the respiratory tracts of market workers, indicating exposure and potential for infection. This study highlighted the importance of surveillance platforms with a coordinated One Health strategy to investigate and mitigate zoonotic risk. [ABSTRACT FROM AUTHOR]

The H9N2 influenza viruses that have become established in Bangladeshi live poultry markets possess five gene segments of the highly pathogenic H7N3 avian influenza virus. We assessed the replication, transmission, and disease potential of three H9N2 viruses in chickens and New World quail. Each virus replicated to high titers and transmitted by the airborne route to contacts in both species. Infected chickens showed no disease signs, and the viruses differed in their disease potential in New World quail. New World quail were more susceptible than chickens to H9N2 viruses and shed virus after airborne transmission for 10 days. Consequently, New World quail are a potential threat in the maintenance and spread of influenza virus in live poultry markets. [ABSTRACT FROM AUTHOR]

Background National media reported a febrile illness among dormitory residents of a boys' religious school. We investigated the outbreak to identify cause. Methods Individuals with fever (>100°F) and cough or sore throat between 1 and 13 August 2011 were influenza-like-illness ( ILI) case-patients. We collected histories and specimens from hospitalized case-patients and visited campus to explore environmental context. Results All 28 case-patients were dormitory residents including 27 hospitalizations. Accommodation space per resident was <0.8 square metres. Nasal and oropharyngeal swabs from 22 case-patients were positive for influenza B virus using real-time reverse transcription polymerase chain reaction ( rRT- PCR). Conclusions Overcrowding likely facilitated transmission leading to this dormitory outbreak. [ABSTRACT FROM AUTHOR]

Avian H7N9 influenza viruses may pose a further threat to humans by reassortment with human viruses, which could lead to generation of novel reassortants with enhanced polymerase activity. We previously established a novel statistical approach to study the polymerase activity of reassorted v RNPs (Influenza Other Respir Viruses. 2013;7:969-78). Here, we report the use of this method to study recombinant v RNPs with subunits derived from human H1N1, H3N2, and H7N9 viruses. Our results demonstrate that some reassortant v RNPs with subunits derived from the H7N9 and other human viruses can have much higher polymerase activities than the wild-type levels. [ABSTRACT FROM AUTHOR]