Stress on RT-PCR to bring down Covid testing numbers in Kerala

THIRUVANANTHAPURAM: The government changing the Covid testing strategy by relying more on RT-PCR tests even when the pandemic situation has not changed much has baffled health experts in the state. The RT-PCR test, considered the gold standard for diagnosing Covid, has limitations in terms of scale and the turnaround time. Health experts are of the view that rapid antigen tests (RAT) hitherto used widely has helped the state to detect maximum number of positive cases and restrict the spread of infection. 

The government defended the use of RAT even when other states had completely switched over to RT-PCR. The sero survey conducted by ICMR also validated the case detection rate of the state which was much better than the national average. However, the situation changed with the new testing strategy announced by the health department on August 28. 

It recommended RT-PCR tests on symptomatic and RAT on asymptomatic persons in places with at least 80% population receiving one dose of vaccine. On September 10, the chief minister said RT-PCR would be the standard test and antigen test would be used in select situations, as the overall vaccine coverage had improved. 

However, health experts have raised concerns of inadequate testing leading to further spread of infection. The state reported 15,692 new positive cases when 89,722 people were tested with a test positivity rate of 17.5%. The low testing was mainly because of Sunday. The health experts stressed the need to conduct the maximum number of tests to identify as many people with infection as possible. According to them, a high TPR also indicated that a lot of infected people are not being tested. 

To be sure, the number of RT-PCR tests conducted in the state has almost doubled from earlier. However, the health experts are still not convinced of effectiveness of the new strategy. The total number of daily tests has come down since September 10 even when the TPR has remained more or less the same (15-18%). 

Though the vaccination has increased, various studies pointed out that the viral load in a vaccinated and unvaccinated person remain the same. The vaccines have proved to be effective in preventing morbidity and death. The Covid deaths have also remained high steadily. Even if most deaths happen among the unvaccinated, the low level of testing and the risk of undetected persons spreading the infection remains the same, according to experts.

“The change in testing strategy defies logic. It happens at a time when the acceptance of antigen tests has increased worldwide. For symptomatic persons, RAT is still good enough to detect the infection and isolate them quickly. The RT-PCR test takes time to get the result. People who wait for RT-PCR results are unlikely to observe the quarantine rules, thereby increasing the chances of spreading,” said internal medicine specialist and public health activist Dr N M Arun. At present, over 70% of the samples are tested using the RT-PCR method.