The story so far: The second wave of COVID-19 , which began rising in Kerala in the second week of April, peaked mid-May, when the State was reporting around 44,000 cases daily and had about 4.45 lakh active cases in the community. The test positivity rate (TPR) hovered around 30%. The State then went into a total lockdown for over a fortnight, after which the case graph came down. But since the past one month or more, the epidemic curve has remained on a plateau , logging around 10,000 cases-12,000 cases every day, and the TPR is at 10%-11%. At a time when COVID-19 cases across the nation have come down sharply, Kerala accounts for about 30% of the country’s active caseload. In the past two weeks, the case graph has been rising again, recording a 20% growth. On July 17, Kerala reported 16,148 fresh COVID-19 cases . Maharashtra, which has also seen cases rising, registered 8,172 fresh cases on the same day.
Why is the epidemic curve not coming down?
Public health experts point out that what is happening in Kerala now is no different than what was witnessed in the State after the first wave. The first wave peaked in Kerala by the end of last October, the curve plateaued and remained unchanged for a long time. In January-February, recording between 1,500 and 3,000 fresh cases daily, Kerala accounted for over 45% of the active cases in the country.
The epidemic curve never hit the baseline after the first wave in Kerala because of two things — the large-scale mixing of people and huge gatherings and rallies during the campaigning in February ahead of the election in April, which was followed by the arrival of the highly transmissible Delta variant .
The first wave was yet to taper down, when Kerala rode into the second wave with a daily caseload of over 2,500 in the second week of April. The case graph then rose exponentially to reach a daily tally of almost 45,000 cases by mid-May. Other States had already experienced the worst of the second wave when the curve began rising in Kerala. Because the second wave was delayed, the epidemic curve in the State is expected to remain on a plateau for a prolonged period and at a higher daily average of fresh cases (because of the Delta variant).
What is the rate of community transmission?
The third round of the national sero-prevalence survey, conducted by the Indian Council of Medical Research (ICMR) in three districts of Kerala in January, revealed that only 11.6% of the population had been exposed to the virus, against a national average of 21%. This meant that when the second wave struck, 89% of the State’s 3.5-crore population was immunologically naive and at risk of contracting COVID-19.
When a highly transmissible virus variant like Delta is in circulation among a susceptible population, the level of efficiency with which the community was maintaining non-pharmacological means of protection against the virus (masking and physical distancing) will no longer be enough to check transmission. Cases will continue to occur till a chunk of the population is affected or the transmission is reduced substantially through vaccination. Testing has been consistent in Kerala, with an average of 1.3 lakh samples tested daily. The official stance is that Kerala is picking up one out of every three infections in the community, while the national rate is one in 25 infections.
What has been Kerala’s strategy?
Kerala’s strategy in COVID-19 containment has always been to keep a tight check on transmission through targeted testing, contact-tracing and isolation of infected individuals. The attempt was always to delay the peak of the curve and spread out the infection so that the cases never exceeded the health system capacity. At the peak of the second wave too, though the health infrastructure was severely stressed, the State managed to tide over the situation fairly well. There were tense situations but people were never denied care nor were there distressing scenes of people running around for oxygen beds or ventilators.
Unlike the sharp rise and fall of the epidemic curve in most States, Kerala’s epidemic curve had a gradual rise and decline. This means that while the duration of the epidemic would be longer, the impact on the community would be less.
What is the current situation?
A prolonged plateauing of the epidemic curve and a slight increase in transmission after the lockdown was expected. However, a 20% growth in cases after the plateau over the last two weeks is beginning to look worrying. Cases are going up mainly in the northern districts. The active caseload, which came down below the 1-lakh mark, has climbed to 1.24 lakh again, and while ICU occupancy is down, new hospital admissions are showing a rising trend.
Did something go wrong post-lockdown?
The State’s current strategy of allowing relaxations, solely on the basis of TPR, has turned out to be unscientific, counter-productive and has been criticised by the scientific community as well as the people. The reliability of TPR as an epidemiological indicator of disease transmission is dependent on who is being tested. Testing among primary contacts of the known COVID-19 cases and high-risk individuals will show more infections in the community but this will mean an increased TPR and another round of lockdown. Now that the government has linked TPR to lockdown relaxations, the reduction of TPR has become the goal for local bodies. Rather than targeted testing, the focus is now on reducing TPR by organising mass testing camps where asymptomatic people are offered incentives to test themselves. Increasing the denominator by testing a large population and testing within a relatively low-risk population can artificially bring about a reduction in TPR.
The State has to break the transmission now by finding active pockets of disease in the community through diligent targeted testing and tracing of primary contacts and high-risk individuals. “What is needed is micro-containment, rather than closing down an entire panchayat based on TPR. Skewed policies such as restricting the opening of shops to certain days of the week is actually leading to overcrowding and super-spread events,” a Health official admitted.
What happens next?
Going forward, increasing the pace of vaccination and keeping a sharp eye on the circulation of SARS-CoV-2 variants through continuous genomic surveillance assumes importance.
Compared with the rest of India, Kerala has managed vaccination very well, administering the first dose to 45% of its population above 18 years and the second dose to 17% as on July 17. Though the State has the capacity to administer 2.5 lakh-3 lakh doses a day, erratic vaccine supply has made this impossible.
The State is ahead as far as genomic surveillance goes, with institutions doing targeted sequencing, apart from the whole genomic sequencing done at national institutes. Over 80% of the samples analysed in the State in recent months have been the Delta variant, though more cases of Delta Plus have also been surfacing.
Kerala is also planning to do a sero-prevalence survey soon, including among children. The sero-positivity is expected to be much higher than what it was during the ICMR survey in January, given that over 31 lakh people have already had COVID-19, and have natural immunity, apart from the proportion of the population who have vaccine-derived immunity.