When the coronavirus infection cases in Delhi reached a new height, the authorities got all hands on deck and formulated a new set of strategies to combat the virus. One of them was to conduct a serological survey in the state, to determine the percentage of people affected with coronavirus.
The results for the same were declared on 21 July by the Ministry of Health and Family Welfare. According to the results, 22.86% of the Delhi population has IgG antibodies against coronavirus in this bloodstream. This means that 22.86% of the people in Delhi have been exposed to coronavirus.
The survey conducted between June 27 to July 10, examined the samples of 21,387 Delhi citizens. What’s shocking is that the study indicates a large number of coronavirus patients in Delhi are asymptomatic.
What is a Serological Survey?
A serological survey is conducted to assess the antibodies against a particular infection in the population. It is mainly used to diagnose autoimmune diseases and certain infections. However, the survey can only account for past or chronic infections and not the acute ones. The serological survey got the ICMR approval due to its high sensitivity and specificity. A biotechnology based test known as Elisa Linked Immunosorbent Assay (ELISA) was employed to conduct the survey. It detected the level of IgG antibodies against the coronavirus in the citizens of Delhi.
However, due to the enormous Delhi population, it is not possible to conduct the serological survey on every doorstep. Hence, it is mainly used to estimate the spread of infection in a community. In Delhi, the serological survey was carried out by 160 teams of four members each between June 27 and July 10. The teams included one Anganwadi/ASHA worker, a midwife, a pharmacist, and a phlebotomist (person trained to draw blood).
What do the Results Indicate?
According to the results announced by the Ministry of Health and Family Welfare on Tuesday, 22.86% of Delhi’s population has IgG antibodies. This level of seropositivity cannot be undermined. As of Tuesday, the total number of coronavirus cases in Delhi is 1,24,000.
A leading epidemiologist and former Dean of Christian Medical College, Dr. Jayaprakash Muliyil, reviewed the Delhi serological survey. He said, “The seroprevalence in Delhi is considerably high. There are some questions on how long the immunity will last. I think it will be a long-lasting immunity, but I cannot give you an exact number.”
He further added that, “The high percentage shows that the real magnitude of the virus is higher than the total number of positive cases in the city. In a few weeks, Delhi will attain herd immunity.”
Taking cognizance of the results, the Delhi government said that there’s still a large population that’s vulnerable to coronavirus. Therefore, the government will implement the safety measures with the same vigour that it had before. Furthermore, the government has urged its people to remain calm and follow all the necessary social distancing guidelines.
