India's high use of antigen tests risks underestimating COVID-19 spread, says diagnostician

Thyrocare Technologies

28/10/2020 11:33

By Krishna N. Das
    NEW DELHI, Oct 28 (Reuters) - Fast but less accurate "rapid
antigen tests" now account for 60% of all coronavirus tests in
India, the head of a top diagnostic firm estimated on Wednesday,
warning that such a high use could misrepresent the actual
spread of the infection.
    Antigen devices return results in about 15 minutes compared
with several hours for the reverse transcription polymerase
chain reaction (RT-PCR) method, a laboratory-based process which
the U.S. Centers for Disease Control and Prevention calls the
"gold standard https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antigen-tests-guidelines.html
" for COVID-19 detection.
    Whereas antigen tests typically detect the virus around 80%
to 90% of the time, lab-based tests detect the virus more than
95% of the time, say regulators and health experts in countries
like the United States.
    As a consequence of the reduced accuracy, India's high use
of antigen tests compared with a global use of around 10%,
risked underestimating the spread of coronavirus, according to
the founder of Mumbai-based Thyrocare Technologies Ltd
 THYO.NS , one of India's top-three diagnostic chains.
    "It's a wrong scale used to assess" the extent of the spread
of the virus, Arokiaswamy Velumani told Reuters in a phone
interview.
    Though the total number of coronavirus cases reached close
to 8 million on Wednesday, India's official tally shows daily
new cases have dropped sharply since a mid-September peak.
 urn:newsml:reuters.com:*:nL1N2HJ09F
    Velumani said Thyrocare's centres are now receiving only
about 2,500 samples a day for RT-PCR tests, down from a high of
about 7,000 in September.
    The health ministry and the Indian Council of Medical
Research did not immediately respond to emails from Reuters
seeking comment on Velumani's comments.
    RT-PCR dominates in the United States but authorities there
are planning to increase the use of antigen tests to screen
people.  urn:newsml:reuters.com:*:nL1N2G810S
    India's federal health ministry has not provided a breakdown
of the test methods deployed, but state and federal officials
have repeatedly defended the use of antigen tests to quickly
identify infections in the country of 1.3 billion people.
    It has also helped India quickly ramp up its testing
capacity to 1.5 million samples a day.
    "There was a stigma that India was not doing enough tests,"
Velumani said, noting at least that criticism was being
addressed.

 (Reporting by Krishna N. Das; additional reporting by Savio
Shetty; Editing by Simon Cameron-Moore)
 ((Krishna.Das@tr.com; +91 987111 8314;))