A new study has found that 80 percent of Mumbai's population has already been exposed to COVID-19 and thus the impact of the probable third wave is unlikely to be as devastating as the second wave.
The study conducted by the Tata Institute of Fundamental Research (TIFR), however, said that a large number of infections may be reported if cases of reinfections spike due to decaying antibodies or if a variant in the virus is able to break through the immune response.
The study estimates that about 80 percent of Mumbai’s population has been exposed to COVID-19 until June 1. This includes 90 percent of the population in slums and 70 percent in non-slums areas.
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"Mechanisms need to be in place that can continuously measure the emergence of reinfections and variants that can break through existing immunity, including immunity provided through vaccines,” the report said, as quoted by the Indian Express.
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 study, headed by Dr Sandeep Juneja, dean of TIFR's school of technology and computer science, found that if vaccination coverage is extensive in June, July, and August and the vaccine is 75-95 percent effective “the (Covid) wave will be barely noticeable even by September”.
The report also noted that during the second wave of COVID-19, Mumbai recorded the highest single-day spike of 11,202 coronavirus patients.
While Delhi and Bengaluru saw a peak of 28,000 COVID-19 cases and 25,000 Covid-19 cases, respectively.
Meanwhile, the COVID-19 cases in Mumbai have dropped significantly over the last few weeks. The city reported 562 new coronavirus infections, the fifth instance of under-600 case count this month, and 12 fresh fatalities on June 29.
Mumbai has a COVID-19 recovery rate of 96 percent, while the average growth rate of cases between June 22 and June 28 was 0.9 percent, the BMC said. The city had reported the highest-ever 11,163 COVID-19 cases on April 4, while the most deaths in a day during the second wave - at 90 - were recorded on May 1.