Only 44 per cent of Kerala’s population above the age of six years had so far been infected by the coronavirus, against the national average of over 67 per cent, according to the state-level serosurvey data released by the Government.
This, in effect, means that a much larger proportion of the population in the state is still susceptible to the disease compared to many other states. Also, the number could, at least partially, explain why Kerala is continuing to report a high number of cases.
For the last two days, Kerala has reported over 22,000 infections, over 50 per cent of the national count. The state has been reporting the maximum number of cases in the country for several weeks now.
This seeming dichotomy — very high reporting of cases for a prolonged period, as well as low disease prevalence — can be explained by the fact that Kerala has had a much better record of detecting infections. Earlier serosurveys had shown that while only one out of 26 infections in the country were detected, in Kerala this number was one in five.
The state has so far detected more than 33 lakh infections. One detection in five would mean that over 1.6 crore people in the state have so far been infected, or about 45 per cent of its 3.6 crore population.
Nationally, over 3.1 crore positive cases have been detected. Given the serosurvey data, this means that at least 80 crore people have so far been infected with the virus. This is consistent with the serosurvey’s finding that about 67 per cent of the country’s population above six years of age has been infected.
Maharashtra, the state with the highest case count in the country, also has a relatively low disease prevalence. The data shows that about 58 per cent of Maharashtra’s population has so far been infected. This could mean that even Maharashtra had done an above-average job at detecting and reporting the infections.
The results of the serosurvey show that the disease prevalence was the highest in Madhya Pradesh, where about 79 per cent of the population could already have been infected. This number was 76.2 per cent in Rajasthan, about 76 per cent in Bihar and 71 per cent in Uttar Pradesh.
The Centre, meanwhile, has asked all the states and Union Territories to conduct more serosurveys in consultation with the Indian Council of Medical Research (ICMR) to generate district-level data on disease prevalence. The Health Ministry said this was essential in formulating localised public health response measures.
“The Union Health Ministry has referred to the findings of the 4th round of National Sero-Prevalence Survey done by ICMR and has advised the States to conduct the sero-prevalence studies in their own States/UTs in consultation with ICMR, so that such studies follow a standardized protocol, and the findings of such studies can then be utilized quickly by the respective State/UT to guide objective, transparent and evidence-based public health response to COVID-19,” the ministry said in a statement.
According to the serosurvey, Uttar Pradesh has a population of over 22 crore. A 71 per cent seroprevalence among those above six years of age would mean that about 14 crore people in the state would have been infected. The state has so far reported about 17.1 lakh cases. That would mean that Uttar Pradesh has been able to detect one in over 80 infections, much higher than the national average of one in 26.
Although the number of susceptible people in UP, over 7 crore, is far greater than in Kerala, the proportion of susceptible population is far lesser. In any random group, there are far fewer number of people who can potentially be infected. This could, at least in part, explain the slowdown in Covid numbers in the state. Uttar Pradesh is currently reporting cases in double digits every day.