One in 15 individuals aged 10 years and above were estimated to be exposed to SARS-CoV2 by August, showing that a considerable population is still susceptible to COVID-19, according to the ICMR's second sero-survey findings released on September 29.

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Presenting the nationwide sero-survey at a press briefing, ICMR Director-General Dr Balram Bhargava said 6.6 percent of the 29,082 people, aged 10 and above, surveyed from August 17 to September 22 showed evidence of past exposure to COVID-19 and 7.1 percent of the adult population, aged 18 and above, also showed evidence of past exposure to it. He said lockdown, containment and behavioural change at the population level have effectively checked the potential spread of SARS-CoV2. "However the survey findings show that a considerable population is still vulnerable and susceptible to coronavirus infection".

Bhargava further said the risk in urban slums was twice than that in non-slum urban areas and four times the risk in rural settings. "Urban slums (15.6 percent) and non-slum (8.2 percent) areas had higher SARS-COV2 infection prevalence than in rural areas (4.4 percent)," he said, sharing the findings from the second sero-survey. "One in 15 individuals aged 10 years and above were estimated to be exposed to SARS-CoV2 by August 2020," Bhargava said, adding, "Earlier we were under the impression that it does not affect those below 18, but now we have found there is no difference. The seroprevalence was not different by age group or gender."

The second sero-survey was conducted in the same 700 villages and wards from 70 districts from 21 states which were covered during the first survey. But this time, it surveyed different households and individuals, the ICMR DG elaborated. The first sero-survey in May revealed the prevalence of novel coronavirus infection to be 0.73 percent among the surveyed population. Also, there were 26 32 infections per reported case by August as against 81-130 in May, which underlines the effect of scaled-up testing tracking and treating strategy, Bhargava said.

Since a large proportion of the population is still susceptible, prevention fatigue has to be avoided and the 5T strategy -- test, track, trace, treat, technology -- has to be adhered to, he underlined. The second survey further showed that there is a lower infection to case ratio in August compared to May which reflects a substantial increase in testing and detection across India. Presenting findings of seroprevalence in cities like Delhi, Mumbai, Ahmedabad, and Puducherry, Bhargava said in the national capital's first round of sero-survey, conducted from June 27 to July 10, as many as 21,387 samples were tested and seroprevalence of 23.5 percent was found.

In the second round conducted between August 1 to 7, as many as 15,000 samples were tested and the seroprevalence was found to be 29.1 percent while in the last one, it was 32-33 percent. In a serosurvey done from June 16 to July 11 in Ahmedabad, the seroprevalence was 17.6 percent. The survey done Mumbai from June 29 to July 19 found that seroprevalence was 15.8 percent in the slums and 17.4 percent in non-slums. As for Puducherry, the seroprevalence has gone from 4.9 percent in the August 11-16 survey to 22.7 percent in the September 10-16 study. "If you look at the international figures, the latest one has come out from the US which shows the seroprevalence at 9.3 percent in a survey conducted in July with 28,503 samples being tested as a part of the exercise. "In Spain, it is 4.6 percent, in the UK the seroprevalence is about 6.9 percent. The highest is probably in Iran which is 22 percent at the moment in terms of the country prevalence and rest of them all are below," Bhargava said.

The NITI Aayog member urged people to keep following COVID-appropriate behaviour like wearing masks and maintaining social distancing, saying there is no reason to be lax if stability in coronavirus cases is to be observed. "We need to have Puja, Chhath, Diwali and Eid with masks to curb the spread of COVID-19. A second peak is coming in the world and we have seen a second peak in Delhi, Kerala and Punjab. So, we should not get lax and keep following COVID-appropriate behaviour," he said.

People are more prone to respiratory infections like pneumonia and influenza in the winter months and festive seasons Thus "we have to put in all efforts, stay vigilant and diligently follow COVID-appropriate behaviour", the NITI Aayog member said. The Union Health Secretary said India has 4,453 COVID-19 cases and 70 deaths per million population which is among the lowest in the world.

Informing reporters that in the last seven days, India has recorded 425 new cases per million population, he said, the country has crossed the mark of 50,000 tests per million population. A month-wise analysis also shows a rapid increase of testing with 2.97 crore tests done in this month itself, the health secretary said. "India has achieved the capability of conducting 15 lakh tests per day. The number of tests done depends on various factors including the intensity of infection spread in an area. Hence, on a day-to-day basis, the number of tests may increase or decrease," he said. He also highlighted that another analysis of a national trend shows that new recoveries have exceeded new cases in recent days. Further, an analysis of data since September 15 shows a sustained decrease in the percentage of active cases and a rise in the percentage of recovered cases, the Union Health Secretary added.