A health workers keep records of swab test samples of the passengers who off loaded at LIT railway station in MumbaiMUMBAI: A mathematical model analysing the reasons for the second Covid wave in the city and the future trends suggests that the rising graph of Covid fatalities will peak in the first week of May. Covid cases peaked a few weeks before May 1 in Mumbai. Analysing the vaccination trends, a paper presented by a team of scientists from Tata Institute of Fundamental Research (TIFR), Mumbai, stated that in scenarios matching Mumbai’s inoculation drive (age-based vaccinations of 15 to 20 lakh new people a month; 75% efficacy), Covid fatalities will reduce to near January- and February-levels by June 1. If the vaccination continues without a hitch, and there is no threat from a new variant, Mumbai may be in a position to open schools by July 1 or soon thereafter, it added. “Of course, as in any forecasting exercise, further off the horizon, more error prone are the projections. So closer to July would be the right time to make this evaluation,” said TIFR dean Dr Sandeep Juneja, who led the team. The ongoing second Covid wave affected 2.3 lakh Mumbaikars and claimed 1,479 lives in April alone. On May 1, the city registered 90 deaths, the highest single-day toll this year so far—the highest-ever in the pandemic was 120 on June 24, 2020. The mathematical model hints that a variant of the SARS-CoV-2 virus led to the second wave and local train services played a role in its spread. The TIFR team said that the variant was possibly in circulation in Mumbai and other larger districts in Maharashtra in February when the city reopened and local trains started plying at near-normal frequency. As the crowds on roads and trains increased, the variant found a conducive environment to spread and create a ferocious second wave. The paper said, “Opening up of the economy at any time before or after February would have led to growth in variants (since it’s unlikely that a large proportion of population would have been vaccinated any time soon), and that is the suggested key reason for the severe second wave as per our computational experiments.” Local trains certainly played an important role in expediting their spread, it added. The scientists said that most factors blamed for the second wave, such as poor Covid-appropriate behavior, increased reinfections, and increased lethality in the virus, or combinations, by themselves do a poor job of matching the second wave pattern. “We find that the most likely explanation is the presence of a small amount of extremely infective variant on February 1 that grew rapidly thereafter and became a dominant strain by mid-March. The scenario where the variant is 2 to 2.5 times more infectious than the dominant strain last year, and accounts for 2.5% of the infected population on February 1, appears to match the data well,” said the paper. Given the large uncertainty in model parameters, the above numbers may be far off from the truth. However, the observation that Mumbai had highly infective variants that grew to have substantial presence in March is likely to be true. As the second wave patterns in other districts like Pune, Thane, Nashik and Nagpur followed Mumbai’s pattern closely, the doctor said a similar lag may be evident for Maharashtra soon. FacebookTwitterLinkedinEMail