The announcement came as the country on Thursday confirmed its first case of the Omicron variant that was detected in neighbouring South Africa last week, Xinhua news agency reported.
"Booster doses for frontline workers, those with chronic diseases and the elderly to commence with immediate effect," Robert Mudyiradima, the acting secretary in the Ministry of Health and Child Care, said in a statement.
Zimbabwean Vice President and Minister of Health and Child Care Constantino Chiwenga on Thursday confirmed the presence of the Omicron variant in the country.
Daily cases have begun to rise sharply over the past few days from 40 on Sunday to 1,042 on Thursday.
The country says it has acquired enough Covid-19 vaccines, mainly Chinese-made, to inoculate 60 per cent of the population to achieve herd immunity.
As of Thursday, 3,829,636 people had received their first dose and 2,851,625 their second dose.
Zimbabwe's cumulative cases stand at 136,379 with 4,707 deaths.