Antibody coronavirus tests for sale in a shop in Ireland (Simon Roughneen)
DUBLIN — Rapid antigen tests for coronavirus likely work better for larger populations than slower but more sensitive polymerase chain reaction (PCR) tests, Indian scientists have found.
A “computational analysis” comparing testing regimes and results across India, which was recently hit hard by a virus surge, suggests “the amount of testing matters more than the sensitivity of the tests.”
The findings hint that lower- and middle-income countries “might be able to achieve optimal outcomes by concentrating on ramping up testing using less sensitive tests which provide immediate results.”
According to the team, “traditional thinking” suggests the PCR test – sometimes referred to as “gold standard” but criticized for generating false positives – should “ultimately lead to fewer overall infections.”
But a mix of tests works better, according to the research which was carried out by a team from Ashoka University and the National Centre for Biological Sciences TIFR in Bangalore and was published in the journal PLOS.
According to Ashoka’s Gautam Menon, “the trade-offs are in favor of rapid testing” – if the number of people tested is high enough. “Tests are continually improving,” Menon said.
The pros and cons of various tests have stirred controversy, with footballer Cristiano Ronaldo last year slamming PCR as “bullshit” after testing positive but not developing any symptoms of Covid-19, the respiratory disease sometimes caused by the virus.
Many well-off countries have made wider use of antigen tests due to their quick turnaround time, which facilitates entry to events or travel. In Singapore, where scientists have developed a one-minute breathalyzer test and which has one of the world’s lowest related death tolls at 35, the government recently approved the sale of antigen tests in supermarkets.
An exception remains Ireland, where where the government has adopted an “abundance of caution” approach to easing virus restrictions, with indoor drinking and dining at pubs and restaurants banned since December. Antigen tests were described as “snake oil” by Philip Nolan, head of Ireland’s National Public Health Emergency Team, after German supermarket chain Lidl put the kits on its Irish shelves earlier this year.
