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Tuesday, September 28, 2021

Understanding why Kerala’s Covid caseload remains high

Udaya S Mishra, William Joe writes: Test Positivity Rates provide a false picture about the Covid-19 spread. Greater access to testing and greater sensitivity to the virus make Kerala’s numbers higher.

Written by Udaya S Mishra , William Joe |
Updated: September 2, 2021 7:14:08 am
People wearing face masks as a precaution against the coronavirus walk at a pedestrian crossing in Kochi (AP)

The pandemic’s persistence and the devastation of two waves of widespread infection have led to serious scientific engagement with the assessment of its possible trajectories, particularly after the vaccination drive has been in full swing as well as the periodic sero-positivity surveillance. At the onset of the pandemic, the common yardstick of its intensity was the case fatality rates and the use of this measure for comparison was fraught with many limitations.

The primary difficulty was to have the corresponding fatalities of the cases that were in the denominator and, therefore, a lagged measure of case fatality was preferred. However, this measure did not entail an appropriate comparison across the population given that the fatality associated with Covid-19 intensified with pre-disposed risks of the patient in terms of chronic morbidities as well as the age profile along with the presentation of the case at a hospital. Case fatality rates were further conditioned by the available health infrastructure as well as the inadequacy of critical care availability. These limitations have made case fatality rates less visible in the current discourse, following the devastating fatality levels (otherwise understated in government records) and with the rising levels of testing with increasing capacities all across the nation. Alternatively, when two waves of the infection have already passed, it is assumed that a much greater number of the population got exposed to the infection without realising it, and either lost the battle or recovered. This is also the impression that is emerging from the periodic sero-surveillance findings — the numbers seem to be systematically improving over time in the Indian population in general, with wide variations across regions.

The most recent yardstick of Test Positivity Rates (TPR) guiding the trajectory of the pandemic in terms of its potential spread as well as the differential levels of containment measures appears to indicate something that is unbelievable. The trends in sero-prevalence coupled with the levels of immunisation coverage and a very low level of TPR situates the regions of India with relatively poor infrastructure and human resources for healthcare in an advantageous position against regions that have all the systems and protocols in place. The most recent mapping of the infection around the country shows that Kerala is contributing half the national infection rates with unacceptably high levels of TPR. This is not only surprising but raises genuine doubts about the comparability of TPR levels.

Comparability not only depends on the magnitude of testing but also the testing protocols adopted by the health system. Test positivity rates are not merely a function of the levels of testing carried out but also the entire “tracing, tracking and testing” protocol followed by the system. While the spread of infection is undoubtedly shaped by the violation of Covid protocols, it is also largely the asymptomatic carriers that are spreading it within homes or the community. In Kerala, the testing is done in clusters where positive cases are found and the likelihood of positivity is obviously greater than the general population.

The use of interstate comparison of TPRs to comment on a state’s efficiency seems far-fetched, overlooking the manner and extent of testing. Testing is a voluntary initiative — apart from cases presenting in clinical facilities. Kerala’s population has volunteered for more testing because a negative test is a prerequisite for intra-state mobility. Comparisons of TPR should not ignore the fact that access to testing infrastructure varies widely across states. Greater access to testing and greater sensitivity to the spread of Covid-19 makes Kerala’s numbers higher — and more genuine. The TPR mapping across the country could well be illusory, if a large majority is neither tested nor vaccinated, and the sero-prevalence indicates greater immunity compared to Kerala’s population.

If a genuine comparative assessment is to be made then the entire road from the detection of infection to recovery has to be evaluated. Such an evaluation should include the number of patients needing hospitalised care, the rate of their progression to oxygen dependence, ICU care and ventilators and finally, fatalities. In fact, comparative evaluation of this kind is perhaps not possible in many of the northern and eastern states, given the abysmal inadequacy of infrastructure there. In the final analysis, Kerala’s case fatality rate as of August 20 remains among the lowest — 0.51 — of all Indian states and against a national average CFR of 1.36. This bears true testimony to the management of the infection by the healthcare system of the state. The claimed immunity across a majority of Indian states may be falsified again with the emergence of another wave after the festive season.

It is clear that any opportunity to demolish the image of a protocol-driven, well-functioning healthcare system is used by those engaged in competitive politics based on false assumptions. These assumptions can put the entire population at risk of a devastating third, fourth wave. The lesson is to avoid politics and politicisation when it comes to human lives. The pandemic scenario will remain gloomy until and unless vaccination coverage is advanced and healthcare infrastructure is increased to meet future uncertainties.

This column first appeared in the print edition on September 1, 2021 under the title ‘Explaining the Kerala surge’. Mishra is with the Centre for Development Studies, Trivandrum and Joe is with the Institute of Economic Growth, Delhi

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