Antibody test: Kolkata municipal corporation starts process to track asymptomatic cases

KOLKATA: In a bid to map Covid-19 spread in containment zones and trace asymptomatic cases, Kolkata Municipal Corporation health department on Tuesday organised camps in city’s high-risk areas for collection of samples of blood for Covid antibody test.
A serological survey involves testing of blood serum of a group of individuals for the presence of antibodies against that infection to know who has been infected in the past and has now recovered. Health experts said that people who had been infected by Covid-19 develop antibody to the virus. Since many asymptomatic people especially in the containment areas are assumed to have been infected, the antibody test will help in assess the number of people who had been infected unknowingly.

Doctors said that the result of the study will give a clear indication on the extent of the disease spread into the general population.
“The antibody test is for epidemiological surveillance. It will find out people who had been infected earlier at certain point of time during this pandemic but who had not been detected due to reasons like being asymptomatic. If they had been infected they would have the antibody in them,” said Bhaskar Narayan Chaudhury, microbiologist at Peerless Hospital.
“This will ascertain the percentage of the population who had been infected and hence give an idea on achieving herd immunity. For example, if around 70% of people are found to have developed antibody, herd immunity is achieved,” said Sumon Poddar, microbiologist at Institute of Child Health.
The blood samples collected from containment zones in five KMC wards will be sent to ICMR, Chennai, for an antibody test. According to a KMC health department official, the civic body had organised the camp in association with ICMR and WHO and collected blood samples from 100 people in each ward who stay in containment areas but are asymptomatic in nature.
Some of the areas from where the blood samples were collected include Hatibagan (Ward 11), Narkeldanga (Ward 28), Elliot Road (Ward 61), Chetla (Ward 82) and Panchanantala (Ward 90). According to a KMC health department official, these areas were selected as several people have been infected with Covid-19 here.
“We will be using the blood samples as serological tools for detecting the antibody against Covid-19 in general population who are mostly asymptomatic,” a KMC health department official said.
According to Atin Ghosh, the member of Board of Administrators (BOA) that now governs the KMC more blood samples would be collected in the city in future. Ghosh said the civic body was also planning to set up a modern laboratory for antibody test.
“Also, we don’t know conclusively if the antibody in a person who had been infected once can protect him/her from getting infected again. Therefore, we could also look if this antibody is a neutralising antibody,” added Poddar.