Erala with lowest exposure to coronavirus

Sero-positivity in the general population

Kerala has had the st exposure to Sars-cov-2, rding to true infection estis based on serological studew data by the Union governshowed on Wednesday, with 44% of the population projeco have been infected till early compared with nearly 67% ss the country as a whole. e results, based on the study w many people had antibodn a survey involving nearly 00 people, appear to explain la’s current high numbers uggest the state was able to t true infections better than other region. The study was ed out by the Indian Council edical Research (ICMR). e overall sero survey results released last week by the re and suggested two out of three Indians may have been sed to the virus. If extrapo, this would mean roughly million people have been ted by the virus; India’s officovid-19 count on July 10 n the survey ended) was 30 on. Including Kerala, the s with the three lowest estid population exposure were m (50%) and Maharashtra ). The states with the highest sure were Madhya Pradesh (79%), Rajasthan (76.2%) and Bihar (75.9%).

“(The finding) reinforces my point that case numbers mean very little without sero surveys to inform what fraction is being detected,” said Anurag Agarwal,

79 76.2 75.9 75.3 74.6 73.1

71

70.2 69.8 69.2 68.1

66.5

63.1

63

62

61.2

60.9

60.1

58

50.3

44.4

director of the Institute of Genomics and Integrative Biology (IGIB).

He added that this also means the second wave will “run longer for Kerala and Maharashtra because of less steep rise”.

To be sure, the fourth round of the sero study also included those who received vaccines. While the data released on Wednesday did not give a split between those with natural exposure and those with vaccine-mediated antibodies, the information released last week suggests the latter accounts for a very small proportion: Of the 67.6% who had antibodies overall, 62% were not vaccinated, officials said at the time. According to experts, current infection trends and the new data by the health ministry offer two important insights: Kerala may have the least amount of under-reporting, and it has the most number of vulnerable people at present.

“India was able to detect only 1 in 33 cases as of May 31st as estimated from the 4th ICMR serosurvey — Bihar: 1/134; UP; 1/100; MP: 1/86. Detection was much better in Kerala (1/6) and Maharashtra (1/12). Unfortunately, the fingers keep pointing to MH & KL. For detecting cases better?” Rijo M John, a heath economist, wrote on Twitter. Having antibodies reduces the chances of infection almost completely, and experts said last week it could explain why cases have been falling, although they urged caution, pointing to the nearly 400 million people who remain vulnerable to the virus.

Kerala’s outbreak followed a similar trajectory as the nationwide second wave. But since midjune, the test positivity rate levelled out at around the 10-12%. At the same time, this metric fell drastically across the country.

Taken together with the serology estimates of the true spread, this also means the virus spread more gradually within Kerala, helping flatten the curve of infections, while it spread rapidly in other parts of the country.

A second expert said the study findings were not surprising: “Kerala implemented good Covid-appropriate behaviour and strict lockdown since the first wave. The cases went down in places such as Bihar, UP, and Delhi not because people started following Covid-appropriate behaviour but because a significant proportion was already exposed to the infection,” said Dr Sanjay Rai, head of the department of community medicine at the All India Institute of Medical Sciences.

In the last two weeks, the number of new cases in the state has risen by 28%, which could partly be due to increased testing – over the same duration, the number of daily tests has gone up by an average of 10%, while the positivity rate has risen by 1.8%. It could also be on account of Covid-inappropriate behaviour, with the state government rashly relaxing restrictions on account of the festival of Bakrid.