Widespread PCR testing for COVID-19 may not stem an outbreak any more than conducting robust contact tracing and quarantining of symptomatic individuals, according to research from Imperial College focused on the UK.
Instead of mass testing, the paper argues for regular testing in healthcare worker (HCW) communities and contacts of symptomatic individuals.
In the UK and India, the current testing strategy among healthcare workers focuses only on those who are symptomatic. India’s testing strategy focuses on symptomatic contacts of positive cases.
Weekly screening of healthcare workers could cut transmission by a third, depending on the accuracy and timeliness of the results, the paper has found.
It argues for isolating all those with symptoms, rather than waiting for a test result. In Wuhan, quarantining and door-to-door surveying of all suspected cases helped reduce epidemic speed, the paper says.
Instead of testing symptomatic cases only, it argues for testing contacts of symptomatic cases and allowing them to go back into the public if negative.
The UK had a high proportion of healthcare workers who were not working either because of COVID-19 symptoms or because they had household members who had symptoms.
The World Health Organisation has called on countries to “test, test, test” and “test, trace, isolate”. South Korea and Germany have been used as global examples to promote mass testing. In contrast, countries like the UK and US have been criticised for their lack of mass testing.
The Indian government has maintained since the beginning of the pandemic that the country’s strategy would be concentrated testing rather than mass testing, partly because of population size.
The paper uses the example of Hong Kong’s 2003 SARS outbreak, when 20 per cent of those infected were healthcare workers and the government response emphasised contact tracing of positive healthcare workers.
The researchers also reason that contact tracing and faster testing is easier in this community.
In addition to testing all healthcare workers, the paper weighs additional strategies, such as testing healthcare workers who are already self-isolating because of symptomatic household members, testing other healthcare workers who have contacted symptomatic workers, or testing household members of symptomatic healthcare workers.
Several Indian states recently complained of faulty antibody testing results, prompting the Indian Council of Medical Research to halt their use temporarily.
The WHO cautioned against immunity passports as well.
The paper makes assumptions about how infectious the virus is through different phases of infection and how infectious asymptomatic cases are.