Countries straining to contain a second wave of COVID-19 are turning to faster, cheaper but less accurate tests to avoid the delays and shortages that have plagued efforts to quickly diagnose and trace those infected.
Germany, where infections jumped by 4,122 on Tuesday to reach 329,453 cases in total, has secured nine million so-called antigen tests per month that can deliver a result in minutes and cost about $7.75 each. That would, in theory, cover more than 10 per cent of the population.
The United States and Canada are also buying millions of tests, as is Italy, whose recent tender for five million tests attracted offers from 35 companies. Switzerland, where new COVID-19 cases are at record levels, is considering adding the tests to its nationwide screening strategy.
Germany’s Robert Koch Institute (RKI) now recommends antigen tests to complement existing molecular polymerase chain reaction (PCR) tests, which have become the standard for assessing active infections but which have also suffered shortages as the pandemic overwhelmed laboratories and outstripped manufacturers’ production capacity.
PCR tests detect genetic material in the virus while antigen tests detect proteins on the virus’s surface, though both are meant to pick up active infections. Another type of test, for antibodies the body produces in response to an infection, can help tell if somebody has had COVID-19 in the past.
Like PCR tests, antigen tests require an uncomfortable nasal swab. They can also produce more “false negatives,” prompting some experts to recommend they only be used in a pinch.