v25i2

01-02 Surgical face masks were demonstrated to prevent transmission of seasonal coronaviruses, in a study that had 246 participants with suspected respiratory viral infections breathe into a machine and measured exhaled virus levels with and without a mask. 03 HKUMed researchers showed that the serial interval of infection – from when one infected person starts to show symptoms to when the next person infected becomes symptomatic – was shortened by nonpharmaceutical interventions. 03 02 » We were also the first group in the world to demonstrate experimentally that surgical mask partition can effectively reduce COVID-19 transmission between hamsters. Using epidemiological data from Hong Kong, we also showed that transmission tends to occur significantly more often in settings where masks are taken off, such as eateries and bars. » In terms of the effectiveness of social restrictions, the Hong Kong government’s response during the first wave of COVID-19, which did not involve a total lockdown, was considered to have had a meaningful impact based on a sharp drop in cases of another easily-transmitted disease, influenza. The government relied on testing for COVID-19, contact tracing and population behavioural changes, which have less disruptive social and economic impacts than total lockdown. » Nonetheless, tougher measures were shown to be effective, too. A study of 54 countries and four epicentres found that national containment measures, such as stay at home orders, curfews and lockdowns, lowered the daily increase in new cases to less than five per cent within one month. » Better identification and isolation of cases early on in the pandemic was also shown to reduce the chance of transmission later on. The serial interval of cases – used to measure transmission – was cut by more than half, from 7.8 days on January 9 to 2.6 days by February 13. » Air sampling for SARS-CoV-2 around hospitalised patients in negative-pressure facilities demonstrated that SARS-CoV-2 RNA was not detectable by air samplers. 17