Kerala is entering the next phase of the surveillance to contain COVID 19. The disease epidemiology now gets more complicated, demanding a dynamic surveillance strategy, one that will account for early detection and containment of a possible community transmission.
Till now, the focus of surveillance has been on people with a travel history to affected countries in the last one month, both Keralites and foreign and domestic tourists.
The State’s containment strategy of quarantining them and keeping the primary, secondary contacts of all those who test positive under surveillance has been working well. So far, only a handful of primary contacts have tested positive and the infection has not gone to the secondary contacts.
Unlike the U.S., U.K. and Italy which hardly had any time before cases exploded in the community, Kerala has the much-needed time to recalibrate its surveillance and containment strategy with the lockdown in place.
Next crop of cases
“The next crop of cases will be coming up from the pool of the one lakh people who are already quarantined. These numbers will surge initially and then plateau off as there is no more importation of infection. But it would be suicidal to relax. The challenge is to find out if there are any new cases outside this pool because that would be the first indication of a community spread,” says a senior epidemiologist.
One can most likely suspect that community transmission has taken place when the first case outside the quarantined pool (which has no travel history or no known contact with any potential source of infection) turns up. Frontline healthcare personnel have the highest chance of contracting infection from an undetected/asymptomatic COVID 19 case.
“Surveillance of clusters of mild respiratory illnesses amongst hospital staff should be initiated as the first step to detect community transmission. Investigating all serious cases of viral pneumonia in hospitals to detect if any is linked to COVID-19 would confirm the same,” he adds.
Viral pneumonia
It is now established that 80% have mild symptoms and 20 serious illness 20% (who require ICU care, ventilatory support).
“When it comes to viral pneumonia surveillance, even the single case that we pick up could be extremely important because it comes from that small pool of 20%. It essentially means that the remaining the 80% are in the community undetected,’’ he says.
Now that the Indian Council of Medical Research has also suggested expanding the surveillance of severe acute respiratory illnesses (SARI), the State should not delay viral pneumonia surveillance. Because once these hidden or undetected cases in the community surfaces as patient clusters in many places, it would be a lost battle,” a public health scientist points out.
Once rain or summer showers start, the next driver of epidemic could be the glut of flu cases with upper respiratory infection, making it difficult for doctors to distinguish it from COVID-19.
In a crowded emergency room, this could result in an amplification of disease transmission, a scenario which is highly likely in Kerala, he warns.
