Four of the new patients are from Mamit district while three are from Champhai, two from Serchhip and one from Khawzawl district, a report released by the state Information and Public Relations Department said.
Seven of the new patients had returned from Maharashtra and three had returned from Delhi, it said.
Apart from the eight-year-old boy, the remaining nine patients are aged between 21 and 46, the report said.
Nine of the patients are asymptomatic. One has developed coronavirus symptoms and has been admitted to a dedicated COVID-19 Health Centre, it said.
Of the 140 total cases, 131 are active while nine people have recovered.
Mizoram had reported its first COVID-19 case on March 24 and the patient, a 52-year-old pastor who had travelled to the Netherlands, was cured of the disease on May 9.
The northeastern state next reported 12 COVID-19 cases on June 1. Since then, the state has witnessed a spike in the number of cases, taking the count from one to 140 in just three weeks. COR ACD AAR AAR