COVID-19 | Is antibody testing a misplaced priority for the Kerala?

Clinicians say surveillance and early detection alone can reduce ICU admissions and mortality as progression of the disease is fast

April 18, 2020 11:13 pm | Updated April 19, 2020 07:44 am IST - Thiruvananthapuram

Kochi: Medics at the real-time Polymerase Chain Reaction laboratory (PCR lab) at the Kalamassery Medical College Hospital, during the nationwide lockdown in wake of the coronavirus pandemic,  in Kochi, Thursday, April 16, 2020. (PTI Photo)(PTI17-04-2020_000250B)

Kochi: Medics at the real-time Polymerase Chain Reaction laboratory (PCR lab) at the Kalamassery Medical College Hospital, during the nationwide lockdown in wake of the coronavirus pandemic, in Kochi, Thursday, April 16, 2020. (PTI Photo)(PTI17-04-2020_000250B)

Kerala could be misplacing its priorities given the overemphasis on the proposed antibody testing amongst the State population while still going through the COVID-19 outbreak.

The government had announced that it will be conducting “rapid” antibody tests in the community to identify possible community transmission of COVID-19 and for serosurveillance studies, to understand whether a section of the population has already been exposed to the virus covertly.

Severity levels

COVID-19 appears as a mild disease in 80% cases. The manifestation is severe in the remaining 20%, of which 5% might require ICU care.

Clinicians managing COVID-19 cases say early detection and management alone can reduce ICU admissions and mortality.

“We have observed that the therapeutic window to nurse the patient back to health is available only in the first week of illness. After day 7 or 8, once dyspnoea sets in, the progression of the disease is fast and the patient might require ventilator support,” said R. Aravind, Head of Infectious Diseases, Thiruvananthapuram Government Medical College Hospital. Improving early case detection is the key to reducing ICU admissions.

Definitive modality

RT-PCR (Reverse transcription - polymerase chain reaction) is the primary and definitive diagnostic modality which can help in detecting active infection.

But in the second phase of the outbreak, the State did not use RT-PCR as vigorously as it should have. At present, even the available PCR kits are not being used enough.

“PCR was used extensively for testing people who had returned from abroad and their contacts, which helped us quarantine people during their infectious period. As these numbers have dwindled, our aim should be to utilise PCR to test hospitalised Severe Acute Respiratory Illnesses (SARI) cases from the community,” a senior public health professional said.

However, this priority seems to have been usurped by the idea that “rapid” antibody testing is the answer to community surveillance.

A robust surveillance system for SARI within the health system will be more effective and consistent in picking up early warning signals of any silent community transmission.

The expert committee, which is guiding the State government in devising strategies to combat COVID-19, has also been stressing on the importance of SARI surveillance and that PCR testing cannot be replaced by antibody testing.

One lakh tests

The government has already issued orders that it will conduct one lakh antibody tests, among prioritised groups such as health-care workers, policemen, local body representatives, volunteers, and vulnerable groups.

“In the middle of an outbreak, we should be looking for active cases of infection in the community so that they can be hospitalised/ quarantined, thus preventing a local transmission. Active infection, as evidenced by the presence of IgM antibodies in blood samples, can happen only after a week or more after the onset of symptoms. In the case of COVID-19, it is of little use, as by day 7 or 8, the patient would have developed breathlessness and be in hospital,” epidemiologists say.

Except in the case of front line healthworkers in hospitals constantly exposed to infection, doing a sero surveillance study using rapid antibody test kits in the middle of an outbreak will only result in a waste of resources, they feel.

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