Hyderabad: About one-fifth (19.7 per cent) of Andhra Pradesh population may have been exposed to novel coronavirus, according to the state government’s sero-surveillance survey.
The results were declared Friday, after compiling the findings from a two-phase sero survey conducted in August. The first phase, carried out early August, focused on four districts, with 3,750 samples collected from each. The second, conducted in August-end, involved 5,000 samples each from the state’s remaining nine districts.
Sero surveys are meant to identify the level of exposure a population has to a disease. Since the majority of Covid-19 cases are believed to be asymptomatic, the exercise helps yield a truer picture of Covid prevalence by also taking into account people who may have recovered from the disease without even realising they had it.
“This 19.7 per cent is about 1.2 crore people of the state and this number was kind of expected because the sample size we picked was really huge and this time 40 per cent of the samples are from non-containment zones,” State Covid Coordinator Dr K. Rambabu told ThePrint
According to the survey, Vizianagaram, which has the second lowest number of Covid cases in the state (after Krishna), is the district with the highest Covid exposure, at 30.6 per cent. Kurnool (28.1 per cent) and Srikakulam (21.5 per cent) follow.
Krishna district, where the survey was conducted in the first phase, reported a high prevalence of 21.7 per cent.
High sero prevalence in Vizianagaram and Krishna, which are districts with the lowest number of Covid cases, is not unusual, according to Dr Rambabu, who said the results are “well-synchronised” with the ground reality.
Both Krishna and Vizianagaram did not have a single positive case until two months ago, said Rambabu.
Vizianagaram’s non-containment areas have the highest sero prevalence of 30.1 per cent, followed by Chittoor and Srikakulam at 24.4 per cent. Non-containment areas in these districts had a higher sero prevalence than containment areas.
“This also indicates that, in the coming days, Vizianagaram will have a lower number of cases because about 30 per cent have already developed antibodies — that is our estimation. Similarly, Kurnool will also see a low number of cases in coming days,” State Health & Medical Commissioner Katamaneni Bhaskar said.
Dr Rambabu added, “Unlike other places like Haryana or Mumbai, we did not limit the sample size collection to one area or low number. Our sample size is huge — we collected about 52,500 samples spread across the state and did it as per ICMR guidelines of picking one in 10 houses from extreme corners, giving priority to women, made sure no visitors were allowed to that house etc.”
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96.1% cases asymptomatic
An interesting find in the survey is that 96.1 per cent of those found to have Covid antibodies in the survey were asymptomatic. In Chittoor, all the survey respondents found to have Covid antibodies were asymptomatic.
It also indicates that most urban areas have a higher sero prevalence than rural ones.
Krishna district has maximum seroprevalence (35.2 per cent) among the urban population, followed by Vizianagaram (34.7 per cent) and Kurnool with (30.1 per cent). Overall, about 22.5 per cent of the urban population has sero prevalence.
The rural areas of these districts showed a sero prevalence of 14.8 per cent, 29 per cent and 27.3 per cent, respectively.
However, in Chittoor and Srikakulam districts, rural areas had higher seo-prevalence than urban areas. Chittoor’s rural areas reported a prevalence of 21.5 per cent, and Srikakulam, 23.9 percent.
The urban areas of these districts had a sero prevalence of 19.4 per cent and 18.5 per cent, respectively.
Overall, about 18.2 per cent of the state’s rural population was detected with Covid antibodies.
In six out of 13 districts, more women had Covid antibodies than men. Vizianagaram accounted for the highest share of women with Covid antibodies, 31.7 per cent, against 29.5 per cent among the men surveyed in the district.
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