Zimbabwe says the coronavirus variant first discovered in neighbouring South Africa now makes up more than 60% of cases within its borders.
It is the first country outside of South Africa to report that the so-called “501.YV2” variant is the dominant strain.
Botswana, Zambia, Ghana and the Gambia have also found some cases.
The announcement by Zimbabwe’s government comes a day after a national lockdown was extended by two weeks.
Monday saw the delivery of 200,000 Sinopharm vaccines doses donated by China, with rollout set to begin on Thursday.
As reported by Reuters news agency this month, a small-scale study by Sinopharm researchers found that its efficacy against this variant was weaker than against the original virus.
Zimbabwe is expected to receive another 600,000 doses in March.
The BBC’s Shingai Nyoka in Harare says coronavirus cases are on the decline, but Zimbabwe’s 4% fatality rate has the authorities worried.
Since the pandemic began, Zimbabwe has recorded more than 35,000 coronavirus cases, including 1,410 deaths.
South Africa, meanwhile, is offering all of its doses of the Oxford-AstraZeneca vaccine to the African Union for distribution elsewhere on the continent, after a small-scale study suggested it had limited efficacy against the variant in the country.
Health Minister Zweli Mkhize said it was “disappointing” but added South Africa was “determined not to be derailed from our commitment to roll out vaccines in February”.