Effects of strict public health measures on seroprevalence of anti-SARS-CoV-2 antibodies during pregnancy.

INTRODUCTION: A substantial number of people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remain asymptomatic throughout the course of infection. Nearly half of pregnant women with coronavirus disease 2019 (COVID-19) are asymptomatic upon diagnosis; these cases are not without risk of maternal morbidity. Here, we investigated the seroprevalence of anti-SARS-CoV-2 antibodies in an unselected sample of pregnant women in Hong Kong. METHODS: This prospective cohort study included pregnant women who presented for routine Down syndrome screening (DSS) between November 2019 and October 2020; all women subsequently delivered at the booking hospitals. Serum antibodies against SARS-CoV-2 were analysed using a qualitative serological assay in paired serum samples taken at DSS and delivery for all participants. RESULTS: In total, 1830 women were recruited. Six women (0.33%) were seropositive at the DSS visit; this seropositivity persisted until delivery. Of the six women, none reported relevant symptoms during pregnancy; one reported a travel history before DSS and one reported relevant contact history. The interval between sample collections was 177 days (range, 161-195). Among women with epidemiological risk factors, 1.79% with travel history, 50% with relevant contact history, and 0.77% with community SARS-CoV-2 testing history, were seropositive. CONCLUSION: The low seroprevalence in this study suggests that strict public health measures are effective for preventing SARS-CoV-2 transmission. However, these measures cannot be maintained indefinitely. Until a highly effective therapeutic drug targeting SARS-CoV-2 becomes available, vaccination remains the best method to control the COVID-19 pandemic.

Virological response to peramivir treatment in adults hospitalised for influenza-associated lower respiratory tract infections.

An open-label trial on intravenous peramivir was conducted among adult patients hospitalised for influenza-associated lower respiratory tract complications (LRTCs). Virus culture and quantitative reverse transcription PCR (qRT-PCR) were performed serially until Day 10. Peramivir treatment was associated with viral RNA decline as well as culture and RNA negativity, which occurred at rates comparable with those of oseltamivir: by Day 5, viral load decline -2.5 log10 copies/mL [ßinteraction -0.071, standard error (SE) 0.121, 95% confidence interval (CI) -0.309 to 0.167]; culture-negative, 94% (vs. 95%); and RNA-negative, 44% (vs. 36%). Extended treatment of >5 days was required in 69% of cases because of slow clinical resolution and viral clearance in LRTCs. Peramivir was well tolerated. These data are useful for future trial design in this unique population.

Validation of a portable recording device (ApneaLink) for identifying patients with suspected obstructive sleep apnoea syndrome.

BACKGROUND: Polysomnography (PSG) is currently the standard diagnostic procedure for sleep apnoea. This study evaluates the diagnostic accuracy of a portable recording device, ApneaLink (AL; ResMed, Poway, CA, USA) for detection of sleep apnoea in comparisons against PSG. METHODS: The AL device is a three-channel screening tool that measures airflow through a nasal pressure transducer, oximetry and pulse, providing an apnoea-hypopnoea index (AHI) based on recording time. Nocturnal PSG (Alice 4; Healthdyne, Atlanta, GA, USA), with airflow measured by a nasal pressure transducer (ProTech PTAF2; ProTech, Woodinville, WA, USA) and AL recordings were carried out simultaneously in consecutive patients with suspected obstructive sleep apnoea syndrome (OSAS). The PSG recordings were analysed manually by a blinded investigator. The oxygen desaturation index of AL was also compared against the AHI based on PSG. RESULTS: Fifty consecutive subjects with symptoms of OSAS were recruited with mean age of 50 years and body mass index of 27.9 kg/m2. The AHI obtained by the AL device correlated closely to that obtained by PSG (Pearson correlation, r= 0.978, P < 0.001), whereas the correlation between PSG AHI and oxygen desaturation index by AL was also strong (r= 0.895, P < 0.001). Comparison of AHI based on the AL against the PSG demonstrated high sensitivity and specificity at AHI > or =10/h (sensitivity 0.977 and specificity 1.0) and at AHI > or =20/h (sensitivity 0.969 and specificity 1.0). CONCLUSION: The AL portable monitoring device is highly sensitive and specific in quantifying the apnoea-hypopnoea index when compared against hospital based polysomnography in patients with suspected OSAS. The simple device may be useful for screening and diagnostic purpose when access to PSG is limited.

Effects of air pollution on asthma hospitalization rates in different age groups in Hong Kong.

AIMS: To assess the relationship between levels of ambient air pollutants and hospitalization rates for asthma in Hong Kong (HK). METHODS: This is a retrospective ecological study. Data of daily emergency hospital admissions to 15 major hospitals in HK for asthma and indices of air pollutants [sulphur dioxide (SO(2)), nitrogen dioxide (NO(2)), ozone (O(3)), particulates with an aerodynamic diameter of <10 microm particulate matter (PM(10)) and 2.5 microm (PM(2.5))] and meteorological variables from January 2000 to December 2005 were obtained from several government departments. Analysis was performed by the generalized additive models with Poisson distribution. The effects of time trend, season, other cyclical factors, temperature and humidity were adjusted. Autocorrelation and overdispersion were corrected. RESULTS: Altogether, 69 716 admissions were assessed. Significant associations were found between hospital admissions for asthma and levels of NO(2), O(3), PM(10) and PM(2.5). The relative risks (RR) for hospitalization for every 10 microg/m(3) increase in NO(2), O(3), PM(10) and PM(2.5) were 1.028, 1.034, 1.019 and 1.021, respectively, at a lag day that ranged from cumulative lag 0-4 to 0-5. In a multi-pollutant model, O(3) was significantly associated with increased admissions for asthma. The younger age group (0-14 years) tended to have a higher RR for each 10 microg/m(3) increase in pollutants than those aged 15-65 years. The elderly (aged >/=65 years) had a shorter 'best' lag time to develop asthma exacerbation following exposure to pollutants than those aged <65 years. CONCLUSION: Adverse effects of ambient concentrations of air pollutants on hospitalization rates for asthma are evident. Measures to improve air quality in HK are urgently needed.