Coronavirus: 46 cases found for every 100 buildings issued with testing notice, study finds
- University of Hong Kong team analyses testing orders issued to residential blocks from start of pandemic to February 15 this year
- Practice uncovered on average 29 infections for every 100 blocks during first four waves and 46 in fifth one, they say, calling strategy inefficient
The team, which included professors Benjamin Cowling and Gabriel Leung, argued that while building-wide testing had worked well in the earlier stages of the pandemic, it was now past its use-by date and resources should be diverted elsewhere.
“Compulsory testing notices can be an essential method when attempting to maintain local elimination – ‘zero covid’ – and most impactful early in an epidemic when the benefit remains of stemming a new wave,” the academics wrote in a pre-print study posted earlier this week that is yet to be peer-reviewed.
Lockdowns were initially ordered whenever a single infection was found in a building, an exercise known as restriction testing declarations, which exasperated residents.
But health authorities later eased the policy so that testing was triggered by a combination of factors, including viral loads in sewage samples. Residents were also allowed to complete the screening by taking polymerase chain reaction (PCR) tests in community centres within a set number of days.
That approach had yielded only marginal gains in controlling infections, the university team argued.
“However, residential [compulsory testing notices] and [restriction testing declarations] appear to be an expensive method of finding small numbers of infections during periods of sustained community transmission, [and] therefore only make at most a limited contribution to mitigating local spread of infection,” they said.
The team analysed testing orders, including those accompanied by an overnight lockdown, from the start of the pandemic in 2020 to February 15 this year, when the fifth wave driven by Omicron was in its sixth week.
