Despite findings of the latest serological survey, researchers are still not suggesting that Pune city is approaching ‘herd immunity’ against COVID-19.
A new study conducted in Maharashtra’s Pune has revealed found that nearly 85 percent of those who found infected with COVID-19 in an earlier serological survey have developed protective antibodies. The first-of-its-kind finding for any Indian city shows that these individuals acquired immunity from the disease caused by the novel coronavirus.
According to a report in The Indian Express, the findings are the result of a follow-up survey done in five prabhags (comprising three-four municipal wards each) of the city.
A serological survey in July-August found that about 51 percent of the people were infected with the disease.
Serological surveys have been carried out in several Indian cities to map the spread of the coronavirus by detecting antibodies whose presence indicates that a person has been infected by the highly contagious virus at some point of time.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
The presence of antibodies does not necessarily mean that a person has acquired immunity, which is developed only if ‘protective’ or ‘neutralising’ antibodies are developed.
Pune's is the first known study used to follow up on an earlier serological survey to detect the presence of these "neutralising" antibodies in infected persons, the news report said.
This theory is backed by the fact that in the Lohianagar prabhag, which showed the highest disease prevalence in the earlier serological survey, cases have fallen in the last three months. This indicates that there may now be a population-level protection against the disease but researchers have not yet suggested that the city is approaching "herd immunity".
The report quotes Dr Gagandeep Kang, one of the co-authors of the study, as saying that Pune's citizens “must not relax or lower their guards” and that a second wave cannot be ruled out.
As of November 19, Pune had reported 3.44 lakh COVID-19 cases. Of these, 3.19 lakh people had recovered and more than 7,200 people died of the infectious disease.Click here for Moneycontrol’s full coverage of the coronavirus pandemic