Kerala has been buying time through the quarantine, social distancing measures, followed by the total lockdown so that it can push the expected peak of the outbreak to April-end or beyond. The State’s containment strategy has so far been working well and except for one or two unexpected events, the course of the epidemic in Kerala has been along expected lines.
However, as the lockdown period enters the final week and the number of positive cases from the quarantined pool of people have begun to dip, anxiety levels are high in the Health Department as to how the post-lockdown period will pan out. The crucial question would be whether the 21-day period of social distancing has resulted in a reduction in the transmission potential of SARS-CoV-2 virus so that pockets of infection do not lead to another outbreak when the lockdown is lifted.
Two Indian-origin researchers from the University of Cambridge and the Institute of Mathematical Sciences, Chennai, who assessed the differential impact of social distancing measures on the spread of COVID-19 in India, says that a three-week lockdown is insufficient to prevent a resurgence of COVID-19.
The study (‘Age-structured impact of social distancing on the COVID-19 epidemic in India’) suggests that sustained lockdown with periodic relaxation – a 49-day nationwide lockdown with intervals in between – might be the desirable option to prevent COVID-19 surfacing again. The course and nature of the epidemic in Kerala and factors like virus’s infectivity in the State has had disease modellers contemplate different scenarios for Kerala.
Scenario 1
“We could envisage a scenario like Italy or Spain for Kerala, wherein, virus infectivity is very high. Then we might hit the peak after the 21-day lockdown. It will leave 1.25 crore people affected in the State, 10% of which – 11 lakh – will be hospitalised. Some 1.5 to 2 lakhs will be in the ICUs, 80% of which will be the elderly,” points out a health researcher.
However, going by the nature of the epidemic in Kerala and the system response, this is not a scenario that health administrators are really expecting.
Scenario 2
If one were to model a prediction on the disease pattern and infection rate amongst the 1.5 lakh people now under quarantine in the State, then the current delay phase will go on expected lines, with the peak of impact stretched out to April end or May. This might leave 60 lakh people affected in Kerala, with 10% or 6 lakh hospitalised and about 75,000 persons requiring ICU care.
Scenario 3
If one were to study the rate of local transmission in the community that resulted from the imported cases from amongst the pool of 1.5 lakh on quarantine, then the numbers affected would come down substantially. “It is clear that 70% of the cases in Kerala are imported. But the local transmission that resulted in the community from these imported cases never went beyond primary contacts. Even the number of primary contacts that resulted from each of the imported cases is much less. Some 200-plus imported cases in the community now has not been able to produce another 200 cases. This means that the basic reproduction number of the infection (R0 - R zero or R nought) is less than one and the epidemic cannot be sustained,” a senior epidemiologist said.
“This is a very optimistic projection and one we all hope will play out. There are two unknowns which could send all these projections to a toss, a “superspreader” event and the role of asymptomatics in the community in spreading the infection. But all this could change depending on the whether the lockdown gets extended or not. If we stop with a 21-day lockdown, then the scenario might change drastically with the influx of lakhs of Malayalis, who will all need to be quarantined and monitored. This could alter all other projections,” he warns.
