The total number of active cases in the state now stand at 197. Two men, one each from Munger and Vaishali district, have died, while 56 have recovered.
Of the four cases reported on Sunday, one each belong to Pachdewari, Sadar, Phulwaria and Bhore block of Gopalganj district. They included two men aged 19 and 60 years and two women aged 50 and 60 years, said Principal Secretary, Health, Sanjay Kumar.
"We are ascertaining their infection trail. These cases were spotted during home screening," he said.
The state government had on April 16 launched a door-to-door screening initiative on the lines of the 'Pulse Polio' drive to identify COVID-19 cases in the state. The number of samples tested so far is 16,985.
Twenty-eight people were found coronavirus positive on Saturday. Bihar had on Friday witnessed the biggest spike in COVID-19 cases when 53 people tested positive for the dreaded virus.
Of the 38 districts in the state, the virus has spread to 21 districts.
Among the COVID-19 affected districts, Munger registered the highest positive cases with 65 so far while Nalanda stood at second with 34 cases. Apart from these districts, Patna with 33 cases, Siwan 30, Buxar 25 and Kaimur 14 accounted for double-digit cases. AR RG NSDNSD