About 22.1% found positive for antibodies in UP’s sero survey
Around 22.1% of the 16,000-odd people tested in 11 districts of the state during September’s serological survey showed prevalence of antibodies against the Sars-Cov-2 virus, UP government officials said on Thursday.
The 11 districts where the survey was conducted included Ghaziabad, from where blood samples of about 1,440 persons was taken.
The five-day drive to collect the blood samples as part of the sero survey was initiated on September 4 and samples from 45 different areas was collected in Ghaziabad. The samples were sent to Lucknow for testing.
“The survey in 11 districts of the state was carried out and about 16,000 samples were taken and tested at King George’s Medical University for detection of antibodies. These were the districts that had a high number of cases. The results revealed that about 22.1% of the samples were having presence of antibodies,” said Amit Mohan Prasad, UP’s additional chief secretary (health).
The officials, however, did not reveal the district-wise percentage.
This was the first sero survey in Ghaziabad, which has an officially estimated population of about 44 lakh.
A serological survey checks for an immune response against the coronavirus in the form of antibodies in the blood of a random sample of the population. It can help establish how far the disease had spread and how many people fought the virus without showing symptoms.
District health department officials said if the results are extrapolated over a population of about 44 lakh, it would mean that about 972,400 persons were exposed to Covid-19 infection in Ghaziabad.
“If the 22.1% results are extrapolated over the entire population of the district, the results would mean about every fifth person got exposed to infection some way or the other and remained asymptomatic. Besides, they got recovered on their own and were not aware of the infection,” said an officer from the district health department.
The experts said the results would mean that the remaining 77.9% of the sample size is yet to be exposed to the virus.
“The 22.1% positive rate of the sample would mean that the rest of the persons are still not exposed. In case of any second wave, it would mean that the rest can still contract infection. So, utmost precautions are needed. If for instance, we assume that 22.1% of population got exposed, then we arrive at a figure of 9.72 lakh (in case of Ghaziabad). If the total present cases are less than this figure, it would mean that the remaining are still not under the net,” said Dr Lalit Kant, the former epidemiology and communicable diseases head at the Indian Council for Medical Research (ICMR).
Dr VB Jindal, former president of the Indian Medical Association, Ghaziabad chapter, said if a large number of people are still not under the net of testing, it is time that utmost precaution is observed.
“If the total testing is about 5.3 lakh at present, and the district has about 22,000 cases so far, the sero survey results would indicate that we have large number of people who remained asymptomatic and are yet to be tested. It is a good sign. But such people can pass on the infection to others. So, it is of utmost importance that all precautions are strictly observed,” he, added.
Dr Vikasendu Agarwal, the state surveillance officer, said they would not extrapolate the result over the entire population of the state as people only in 11 districts were sampled.
“These 11 districts were those which had a high rate of infection. So, the results of the sero survey are on expected lines and only indicative. The results are an indication of the prevalence of antibodies but it is good sign that it has not spread largely. Also, we have not seen any indication of a second wave so far in the state as our daily cases are still in range of about 2,000-3,000 per day and testing has not gone down,” he, said.
“We were expecting a surge in cases during the festival season but at present we do not have large clusters where infection is prevalent. We conducted targeted sampling before and after festivals but the positivity is very less. However, we are mapping localities that have high number of cases and targeted sampling will be taken up,” he added.
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