What explains Kerala’s sharp rise in COVID-19 cases? Experts weigh in

Kerala, which was once the benchmark for effective COVID-19 management, recorded the second highest number of active COVID-19 cases in India in November.
coronavirus kerala
coronavirus kerala

The 'Kerala model' has come under intense scrutiny after the state, once a poster child for effective epidemic management, reported the second-highest count of active COVID-19 cases  in India since last week. At 86,681 infections as on Tuesday, its total active cases are second only to those in Maharashtra. For a densely populated state, Kerala was reporting fewer than 1,000 cases per day in late July.

But things changed dramatically by August, with the coming of Onam and a spate of violent public protests, triggered by political events. By October 10, Kerala hit a single-day spike of 11,755 cases — the highest number of cases within a 24-hour period. It has since dipped and plateaued at a steady 7,000-8,000 daily cases for five days between October 28 and November 1. In these five days, the state even overshot Maharashtra to report the highest number of daily infections in the country. So what explains Kerala’s sharp rise in COVID-19 cases? TNM spoke to four experts who weighed in on the current scenario in the state.

“It was only bound to happen. Kerala was meant to get infected at some point, as almost the entire chunk of its population was not exposed to the virus. This is thanks to early and effective interventions by the government to curb the spread,” explains Dr Giridhar R Babu, an epidemiologist at the Public Health Foundation of India and a Member of Karnataka's COVID-19 Technical Advisory Commmittee. In fact, the region is practically a ‘fresh territory for the virus to conquer’ and this explains the current number of daily infections as the virus is widespread in the community and is infecting more people every day, adds Oommen C Kurian, senior fellow and head of health initiative at Observer Research Foundation (ORF). 

To understand how ‘unexposed’ Kerala’s population was, Oommen and Giridhar quote the second national serosurvey conducted by the Indian Council of Medical Research (ICMR) in August 2020. The survey revealed a seroprevalence rate of 0.8% in Kerala’s population in August. Seroprevalence is the percentage of individuals in a population who have been exposed to a pathogen (showing antibodies to the pathogen). 

“Going by ICMR’s survey, only 0.8% of Kerala’s population showed antibodies to SARS-CoV-2 by August,” Oommen adds. Compare this to Delhi where  28.3% of the city’s population showed antibodies to the virus and Mumbai, where 45% of the slum population and 18% of the non-slum dwelling population showed antibodies in the same period. 

Most epidemiologists agree that for the spread of the virus to slow down, at least 30-40% of the population must show antibodies to it. By this calculation, and factoring in Kerala’s August seroprevalence percentages, the state could already be peaking and can expect to see a decline in daily infections by November. 

Lockdown fatigue 

But what about its response to the virus, especially post August? 

Oommen says that Kerala may have experienced a ‘lockdown fatigue’ after what was five to six months of ‘aggressive policing and a war-like response to the pandemic’ by the state government. 

“The state relied heavily on its police force and Local Self Government departments to impose lockdowns and physical distancing protocols. This means that a large number of volunteers were working locally to police the population, push them back into their houses. The state police force even went as far as dropping off essential items at people’s doorsteps to make sure they do not step out. This is not a sustainable model as people get used to the new normal after a few months and take things for granted. Also, how long will you keep people indoors?” Oommen asks. 

Moreover, Kerala celebrated Onam- it's biggest festival in August. It also saw hundreds of people from Congress and BJP hit the streets for weeks in protest against the government in relation to the recent gold smuggling scam.

Population density

Virologist Dr T Jacob John, former head of ICMR’s Centre for Advanced Research and emeritus professor at Christian Medical College (CMC), Vellore, says that Kerala succeeded in placing obstructions to prevent ‘free flow of the virus’. 

“Let me compare the COVID-19 epidemic to the floods. Water will flow through all open channels and the water levels in all low-lying areas will come to be more or less the same, but the time taken to reach the level will vary depending on the channel — clean or with obstructions. If obstructions are constructed, the filling will be delayed, but eventually the flood can surpass the obstruction and water level will stabilise,” Dr Jacob explains. 

He then compares COVID-19 cases per million in Kerala, Tamil Nadu, Karnataka and Andhra Pradesh, which stand at 11,625; 9,343; 12,191; 15,142 respectively as on October 30. 

“Tamil Nadu has the lowest per million cases and Kerala is next. Now, compare the wide heterogeneity of people in Tamil Nadu, huge land area and big urban-rural differentials. Kerala is more homogeneous, with a much higher population density. So it hardly has any gaps between habitations and is one large city of 36 million people. So the state should have the highest per million cases. But that is in Andhra Pradesh, followed by Karnataka, Tamil Nadu and then Kerala. Is that not indicative of obstructions created to prevent ‘free flow’?”, he asks. 

Kerala’s population density of 859 persons per square kilometre, as per Census 2011, explains the transmission of the coronavirus and how COVID-19 cases have more or less been reported in all 14 districts, unlike states such as Tamil Nadu and Maharashtra, where infections were concentrated in the metropolises and tier-two cities.  

Dr Giridhar Babu adds that cases reported uniformly could also mean that the state is holding tests in rural areas as well. “In some states such as Maharashtra, big cities such as Mumbai, Thane and Pune reported a high number of COVID-19 cases. But cases reported from rural regions were fewer. This, however, does not mean that there are infections in rural areas. By that argument, Kerala reporting cases from all districts could be a sign that the state is also testing rural populations. This is apart from the fact that the state has high population density,” he says. 

Still not enough testing

But when it comes to testing, the Indian Medical Association (IMA) has routinely requested the state to send more samples to labs, identify and isolate more cases. However, Kerala’s testing strategy has been criticised for its inconsistency, with the daily number of tests swinging from 30,000 on some days to 70,000 on others. “Fewer tests lead to fewer patients being identified and isolated. The undetected ones meanwhile are rapidly spreading the virus in the community,” explains Dr P Gopikumar, Secretary of Indian Medical Association, Kerala. 

Let’s look at the recent data to understand testing in the state. On October 31, Kerala sent 59,999 samples for testing. The number of new cases out of these samples was 7,983, with a test positivity rate of 13.30%. Similarly, on October 28, the state sent 66,980 samples for testing, of which, 8,790 positive cases were recorded (13.12% test positivity rate). Compare this with the results on November 2. The state only reported 4,138 cases of COVID-19. But, it had tested just 33,345 samples on November 2, seeing a drop in the test positivity rate to 12.40%.

While the IMA has asked the state to test 1 lakh or even 1.5 lakh samples a day, Kerala is averaging 50,000 to 60,000 daily tests. “If they do proper contact tracing and testing of exposed primary contacts, the number of tests will automatically jump to 1.5 lakh,” Dr Gopikumar adds. 

The consistently high number of cases, Dr Gopikumar adds, is a result of inadequate testing. “If they ramp up tests to 1 lakh per day, more than 10,000-12,000 cases can be detected,” he says. 

But it’s not just the number of tests that have been criticised. Kerala has been relying heavily on Rapid Antigen Testing (RAT), over the RT-PCR (real-time polymerase chain reaction) tests, which is considered gold standard for testing. The Rapid Antigen test only has a 50% sensitivity rate, which means it shows a lot of false negatives. That is why ICMR has recommended that those who test negative be tested once again using the RT-PCR kit. “However, it is not clear if Kerala is following this through,” Dr Gopikumar adds. 

Low case fatality rate 

Kerala’s case fatality rate, however, has reflected its success in handling the pandemic, experts say. Case fatality rate (CFR) refers to the proportion of people who died from the diseases among a group of individuals who have been infected over a period of time. 

“Case fatality rates in Kerala, Tamil Nadu, Karnataka and Andhra Pradesh are 0.35%; 1.25%; 1.13% and 0.67% respectively (as on November 2). Death rate reflects quality of care and medical interventions — case numbers will equalise but death rates are a better measure of effective management,” says Dr Jacob.

What is remarkable is that Kerala has managed to keep its case fatality rates low despite having a high percentage of senior citizens and persons with comorbidities, adds Oommen. Projected figures from 2018 show that there are 48 lakh persons who are above 60 years of age in Kerala, out of its total population of 3.6 crore. The state is also labelled the ‘diabetic capital of India’ with a study showing prevalence of diabetes in 20%of its population, while the national average is 8%. Diabetes is among a list of comorbidities that is associated with increased COVID-19 related mortality

“The state government staggered the spread of the virus initially and as a result, they were able to ensure that their health infrastructure — beds, oxygen masks, ventilators — was not exhausted. When cases rose, the district administrations were actively adding reinforcements to hospitals to add capacity. All of this definitely helped the state keep its case fatality rates low,” Dr Gopikumar adds. 

However, it must be noted that although Kerala has reported a total number of 1559 deaths, experts have pointed out that this could be more as the state government has not attributed several fatalities to death by COVID-19.

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