Special Secretary (Health) Nipun Jindal said the fresh cases were reported from Kangra district.
The three include a head constable and a man who returned from Punjab's Jalandhar recently.
They tested positive for the infection at Tanda's Dr Rajendra Prasad Government Medical College (RPGMC).
The state has 21 active cases of the virus -eight in Kangra; six in Chamba; two each in Hamirpur and Bilaspur; and one each in Mandi, Una and Shimla.Thirty-nine people have recovered from the infection. DJI DVDV