India could start to see a reduction in the number of Covid-19 cases by next week followed by a substantial reduction by April 30 if the lockdown is successful and if people quickly adhere to containment measures, said an epidemiological study on India’s Covid-19 trajectory.In the case of only a 21-day lockdown, suppression measures like social distancing and sealed borders would have to continue in order to maintain the improvements resulting from the lockdown, the study showed.Conducted by an interdisciplinary group of scholars and data scientists and led by Bhramhar Mukherjee, a professor at the University of Michigan , the study used the susceptible, infected, and removed (recoveries & deaths) (SIR) model to predict the impact of the lockdown.“India has taken stringent measures early on and if the lockdown is effective, and by effective I mean if the transmission of the infection reduces, then we expect to see some reduction in the number of cases by the next week,” said Debashree Ray, an assistant professor at the John Hopkins University , who was part of the study group.Highlighting the importance of adhering to social distancing norms and lockdown guidelines, Maxwell Salvatore of the University of Michigan said, “If there is quick social adherence to social distancing and lockdown measures, then there would be a substantial reduction in the number of cases by April 30,” who was also a member of the study.He added that the study accounted for various models based on the number of days of lockdown and the way in which activity resumed after the lockdown was lifted. “The effects of the lockdown would be negated by June 1 in the absence of any form of suppression post the lockdown, whereas the benefits would extend into the long term if such measures are put in place,” Maxwell said.The results of the study, which is updated online on a daily-basis according to updates of official figures, was announced through a webinar hosted by the National Council of Applied Economic Research (NCAER).While stating that the study considered the reported number of cases, recoveries and deaths as true in India, Mukherjee underscored the importance of reliable data through improved testing. “A benchmark is that behind every death, there are probably 800-1000 cases,” she said, citing other research that estimated the number of cases from the number of deaths rather than reported figures.The study also showed that while there was not much difference in terms of reduction of cases for a 21-day and 28-day lockdown, there was a substantial improvement in the outcome of a 42-day lockdown.