ICMR to start 4th national sero survey this month
Indian Council of Medical Research’s (ICMR) fourth round of sero survey to detect prevalence of Sars-CoV-2 , the virus that causes coronavirus disease (Covid-19), will begin this month in 70 districts across the country. In a letter to the states, ICMR director general also said that this survey will include children aged 6 years and above.
Apart from the general population, blood samples will also be collected of health care workers in district hospitals of these 70 districts in 21 states.
In the letter written on June 4, ICMR director general, Balram Bhargava, said, “ICMR will be conducting the fourth round of ‘National sero-survey for Covid-19’ in June 2021. This sero survey will be conducted in the same 70 districts in which the first three rounds were conducted. The survey will cover general population aged 6 yrs and above and health care workers working in district hospitals of these districts.”
“The findings of the sero survey will help in ascertaining the current Covid-19 situation in India,” the letter further read.
The 21 states where the samples will collected from select districts for sero survey include Andhra Pradesh (Krishna, SPSR Nellore, Vizianagram), Assam (Udalguri, Kamrup Metropolitan, Karbianglong), Bihar (Muzaffarpur, Purnia, Begusarai, Madhubani, Buxar, Arwal), Chhattisgarh (Bijapur, Kabirdham, Surguja), Gujarat (Mahisagar, Narmada, Sabar Kantha), Jharkhand (Latehar, Pakur, Simdega), Karnataka (Bengaluru urban, Chitradurga, Kalaburagi), Kerala (Palakkad, Ernakulam, Thrissur), Madhya Pradesh (Dewas, Ujjain, Gwalior), Maharashtra (Beed, Nanded, Parbhani, Jalgaon, Ahmednagar, Sangli), Odisha (Rayagada, Ganjam, Koraput), Punjab (Gurdaspur, Jalandhar), Haryana (Kurukshetra), Rajasthan (Dausa, Jalore, Rajsamand), Tamil Nadu (Tiruvannamalai, Coimbatore, Chennai), Telangana (Kamareddy, Jangaon, Nalgonda), and Uttar Pradesh (Amroha).
Blood samples in a sero survey are tested for the presence of IgG (Immunoglobulin G) antibodies that determine a past infection due to the virus. Sero surveys are also important to determine whether the disease has entered the community transmission stage or not.
ICMR’s National Institute of Epidemiology in Chennai has been the nodal agency for all past surveys and will most likely supervise the fourth one as well.
The earlier sero surveys suggested that a significant size of the population was still susceptible to catching the viral infection, and India was far from achieving herd immunity. The first one was designed as a cross-sectional survey of adults aged 18 years or more from 21 states, where the districts were categorised into four strata according to the reported Covid-19 cases per million population .
In the second and third rounds, all other parameters were the same except for the age bracket — samples were taken from people aged 10 and above.
The third sero survey, conducted between December 17, 2020, and January 8, 2021, found 21.4% of those aged 10 and above infected with the virus.
In the second round, nearly one in 15 (6.6%) people above the age of 10 was found to be exposed to the virus till August 2020.
The first survey conducted in May last year had found the infection rate to be 0.73% nationally.