NEW DELHI: One person infected with coronavirus can possibly infect 406 others in just 30 days in the absence of a lockdown and social distancing measures, but this can dramatically come down to 2.5 people with a 75% reduction in social exposure, a recent study conducted by the Indian Council of Medical Research (ICMR) shows.“If one person does not follow lockdown and so-cial distancing norms, he can infect 406 people in 30 days. However, if social exposure is reduced by 75%, then the same infected person can spread it to just 2.5 people,” Lav Agarwal , joint secretary in the health ministry, said on Tuesday.“It is, therefore, our appeal to all of you to follow the lockdown and social distancing measures. We should understand that this is a very important intervention in the management of Covid-19,” Agarwal added, citing the study to underline the importance of observing the national lockdown.At present, the mathematical component that represents the number of persons to whom an infected person can spread the disease is between 1.5 to 4 for Covid-19, Agarwal said and added that Union health minister Harsh Vardhan was right in stating that “social distancing is social vaccine” in managing the infection.However, recent reports also suggest that the novel coronavirus often infects clusters of family members and friends. In China, almost 80% of the transmission appears to have occurred within families. A similar pattern has been reported in the United States, too.These trends assume significance in India where family members often stay together and members comprise different age groups, making social distancing a difficult proposition. While the elderly are at a higher risk of severe illness from the disease, the younger members of their family are more likely to be asymptomatic carriers.With 354 new cases of Covid-19 and eight deaths reported in the last 24 hours, the total count of coronavirus positive cases in the country has gone up to 4,421, while total deaths stood at 117, the health ministry said.