The World Health Organisation warned on Friday against relying on results of immunodiagnostic tests such rapid antibody testing as definite proof of coronavirus infection. "Laboratory tests that detect antibodies to SARS-CoV-2 in people, including rapid immunodiagnostic tests, need further validation to determine their accuracy and reliability," a scientific brief by the Geneva-based organisation said on Friday.
"Inaccurate immunodiagnostic tests may falsely categorise people in two ways," the apex global healthcare body said. "The first is that they may falsely label people who have been infected as negative, and the second is that people who have not been infected are falsely labelled as positive," it explained.
A prominent infection expert agreed with the WHO's latest advisory on the rapid immunodiagnostic tests. "The sensitivity is definitely low for all these rapid immunodiagnostic tests," said the doctor, not wishing to be identified.
The scientific explanation from the WHO came as quality concerns are being raised around the rapid antibody testing kits imported from two Chinese companies returned accuracy levels to the tune of five to eight per cent, forcing the authorities to put a two-day moratorium on their use on April 22.
Several requests for a pointed response on allegations against Chinese rapid testing kits returned no response from the WHO, though the scientific advise does address some of the concerns around the reliability of rapid testing kits in general.
The two Chinese companies in the line of the firing of the Indian authorities, Guangzhou-based Wondfo Biotech Co Limited and Zhuhai's Livzon Diagnostics Inc, had also put out press releases rejecting criticism around their rapid anti-testing kits.
"Results from anti-body testing should not be used as the sole basis to diagnose or exclude novel coronavirus infection or to confirm infection status," read the press statement from Livzon, echoing concerns around reliability of rapid antibody testing.
Both Wondfo and Livzon have also noted that their kits had been approved by the Pune-based National Institute of Virology (NIV) on March 20 and in April respectively. They have also released a set of operating guidelines that need to be followed while handling the machines, in terms of storage temperature of samples among others.
Between them, the two Chinese entities exported nearly 6.5 lakh of these kits that Indian healthcare workers were using on those suspected of having been infected. The first consignment carrying the supply reached India after leaving from Guangzhou on April 16, India's envoy in Beijing Vikram Misri had tweeted.
The Indian Council of Medical Research, the specialist government agency coordinating India's medical response to the pandemic, on April 22 flagged the misleading results of the China-made rapid body testing kits, temporary suspending the tests across the nation. The decision has impacted the response against the pandemic by cutting down on the quantum of testing, as states such as Rajasthan, Chhattisgarh and Assam cancelled further orders from these companies and instead turned to South Korean SD Biosensor, whose local subsidiary in Manesar is in process of manufacturing more than 5 lakh rapid body kits for the domestic market.
The Union Health Ministry had revealed during its daily press briefing that the rapid antibody tests were being conducted on residents in 'hotspot' or 'potential hotspot' areas. Neighbourhoods and districts identified as hotspots have a higher doubling rate of infection than other relatively less-affected localities.
China's Ambassador to India Sun Weidong also came out in defence of Chinese kits, stating that Beijing was enforcing "stricter regulatory measures" while exporting products made in the country. "Some countries including India raised their purchasing demands through diplomatic channels, and we recommend qualified companies," read the statement.
Despite ongoing concerns around the inferior quality of incoming Chinese equipment, New Delhi, short of other foreign options, is continuing to source rapid testing kits from Chinese entities. The Ministry of External Affairs official spokesperson Anurag Srivastava said in a statement on April 23 that around two dozen flights departed from five major cities in China, carrying onboard nearly 400 tonnes of medical supplies, including RT-PCR Test Kits, Rapid Antibody Test kits, PPE kits, thermometers, etc.
Weidong said on Friday that a new 'green channel' facilitated by Beijing would carry 35 cargo flights loaded with PPEs, rapid testing kits and other coronavirus-related crucial supplies to India in the coming days.