Delhi will witness a sero survey during the first five days of every month, starting August 1, the AAP government has announced. The move comes a day after the Ministry of Health and Family Welfare announced the results of a comprehensive sero surveillance carried out in Delhi between June 27 and July 10. The results showed that 22.86% of the 21,387 people surveyed had been exposed to Covid-19.
“A survey was done last month in Delhi to check the prevalence of the disease, and the results show that almost one-fourth of Delhi’s population has been infected with the virus and have now recovered. Most of them were not even aware that they had been affected. The government has now decided to conduct a sero surveillance every month to assess how many people have been infected with the disease,” said Delhi Health Minister Satyendar Jain Wednesday.
The recent survey collected samples from across 11 districts of the capital, which were then divided into two groups — of less than 18 years and older. The survey carried out by the National Centre for Disease Control (NCDC) along with state health authorities also concluded that 77% of the remaining population continues to be vulnerable to the virus — and that rigorous measures to enforce containment zones are necessary.
“We will collect more than 21,000 samples. We are doing it again to identify further spread of the disease and to formulate policies for containment and management. It will be a representative sample of the society, which will include people from all age groups. We are developing a strategy as per scientific evidence,” Jain said.
This will be the third serological surveillance to be carried out in Delhi. Earlier, ICMR had conducted a pilot sero survey in April across 83 districts in 21 states. That survey, carried out in containment zones of Delhi’s Southeast district, showed a prevalence of 9-11% of the disease.
Asked about community transmission and where the city stood in terms of herd immunity, Jain said: “There is a spread in the community as around 23% of people have been infected and recovered. The decision to call it community transmission has to be taken by the NCDC and the Central government. According to experts, if 40-70% people have been infected and recovered, then herd immunity is developed. At present, it is not feasible to say that herd immunity has developed in Delhi.”
Jain further added that the percentage of deaths due to Covid-19 in July is far less than in June.
During the recent sero survey, the ICMR had approved the use of COVID KAVACH ELISA kits for testing. About 160 teams of four members each, comprising anganwadi/ ASHA, ANM, pharmacists and phlebotomists, visited the houses randomly picked by the districts.
On Wednesday, Delhi recorded 1,227 coronavirus cases, taking the tally in the city to over 1.26 lakh, while the death toll from the disease rose to 3,719. Twenty-nine fatalities have been recorded in the last 24 hours.The number of Rapid Antigen Tests conducted that day stood at 14,810 while the RT-PCR, CBNAAT and True NAAT tests figures were 5,250, in all adding to 20,060. The total number of tests done till date in Delhi stands at 8,71,371. The number of tests done per million, as on Wednesday, was 45,861.
At private labs
Earlier this month, all top private hospitals and labs had started antibody testing, where a blood sample is collected to determine if a person is infected with the novel coronavirus. It is also used to detect if the person was infected in the past based on whether antibodies were produced to combat Covid-19.
“We started the IgG antibody test around 10 days ago and have carried out around 3,000 such tests so far. As per the results, around 15-20% of the people have tested positive, which means they have developed certain immunity levels against the virus,” said Dr Arvind Lal, chairman and managing director of Dr Lal PathLabs.
Dr Dangs Lab, which has tested 1,200 people, has found a positivity of 20-25%. “Majority of those who have tested positive are asymptomatic. It is extremely important to understand that the test does not indicate infectivity but is only used for surveillance purpose. It only explains whether the person has been exposed to the virus before. Those who are coming for the test include healthcare workers, other frontline workers, and some professionals who are about to join work,” said Dr Arjun Dang, CEO, Dr Dangs Lab.
Dr Poonam Das, principal director, Max Labs, said: “We are doing a study on 315 individuals who had tested positive for Covid-19 in the RT-PCR test. Around 84% showed IgG antibody positivity after three weeks of infection/symptoms. This is a healthy sign as it indicates not only past infection but also immunity against a particular virus or reinfection by the same virus. We are following up some of these patients to recheck their antibodies after an interval of two weeks — majority are showing a rise in IgG antibody values. It’s too early to say what the trend would be like, but as of now it’s a positive sign, contrary to initial reports shared during the pandemic from countries abroad where it was stated that patients who recovered from the infection were not producing antibodies against it. However, we have to continue following up the count of IgG antibodies to see the trend.
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