A latest sero-study has shown that the actual number of people infected with COVID19 in Kashmir may be at least 35 times higher than detected by testing.
Result of the second round of sero-prevalence study carried out by Indian Council of Medical Research in Pulwama was released last week. The data showed presence of antibodies for SARS-CoV2 among the 27.3 percent of the randomly tested population.
The data stated that at least 27.3 percent of the population in the sample district had been exposed to or infected with COVID19 and had recovered from it. The samples had been collected in the third week of August.
A senior epidemiologist said that the extrapolation of these results to the entire population suggests that in this district, with a population of 5,60,000, at least 1,52,000 may have antibodies for COVID19, after their exposure to the virus. However, till date, as per J&K’s official bulletin on COVID19, less than 4200 people have tested positive in the district. The remaining, 1,47,800 never tested positive, either because they were not tested, or because they never had symptoms, the epidemiologist said. “It means, in other words, that for every case that was detected, there were at least 35 that were missed,” he said.
Prof S Saleem Khan, head department of preventive and community medicine at GMC Srinagar, who was pivotal in executing the study in Pulwama believes that more than 90 percent of the cases of COVID19 would be undetectable. “These, a majority, have no symptoms and we may not capture them during routine surveillance, survey or contact tracing of positive cases,” he said.
Prof Parvaiz A Koul, head department of internal and pulmonary medicine at SKIMS Soura and an influenza expert called sero-positivity a “reflection of an exposure regardless of the symptoms”. “Some of them could have been asymptomatic and some exposed but with minimal symptoms even though the immune response was there,” he said.
He said that an additional factor to consider is that a number of those with symptoms do not develop a significantly detectable antibody response. “All this points to the fact that the number of people that are actually infected is much higher than what we have been able to detect here,” he said.
He cited the recent ICMR data, pertaining to the two rounds of ‘National sero-surveillance to monitor the trend of SARS-CoV-2 infection transmission in India: Community-based surveillance’ carried out in May and August. The data suggests that the actual number of exposed/infected individuals might be 80 to 100 times higher, he said.
“While these numbers are scary but they are also comforting that we have more asymptomatic or minimally symptomatic patients.” He expressed concern over how high population density could mean that small increase in percentages causes alarmingly high numbers in absolute terms.
Prof Khan said the study has shown that COVID19 has been spreading fast over the past three months and in order to prevent casualties, it is important to follow the SOPs.
Pulwama district had been chosen in May, when the first round was carried out, based on its low-prevalence of COVID19 infections. At that time, as per the survey results, only 2 percent of the population was found to have antibodies for COVID19. However, the second round data reveals that 27.3 percent of the population in the sample district had antibodies for COVID19. “Between May and August, the infections spread from 2 to 27.3 percent,” the study showed.