Syrian regime delivered 200,000 vaccine doses
Damascus was sent 200,000 doses of the AstraZeneca vaccine, which was described as "critical and timely" in a joint statement by UNICEF and the World Health Organisation.
They added that the doses would ensure health workers could "continue delivering life-saving services in an already exhausted health system as a result of the decade-long war".
The statement added that more vaccine deliveries would be made in the coming weeks and months.
Opposition-held north-west was also supplied with 53,800 vaccine doses.
Akjemal Magtymova, head of the WHO's Syria mission, said the country has a strong track record when it comes to undertaking vaccination programmes but added that there would be many challenges ahead.
Magtymova had previously stated a goal of vaccinating 20 percent of Syria's populations by the end of the year. To meet this goal, Syria would have to vaccinate around 5 million people across regime and opposition areas.
A Syrian regime programme to vaccinate the 20 million people living in territories under its control plans will include 76 hospitals and a further 300 mobile units who will work in more remote areas.
The conflict in Syria and the difficulty in crossing frontlines makes the job of vaccinating the general population incredibly challenging, which is further hampered by the international sanctions imposed on the country.
Regime-held territories in Syria experienced two major spikes in infections in August and December, with a further spike reported by health workers in February.
Official numbers have recorded 51,580 cases of Covid-19, although the true number is believed to be much higher, due to limited testing capacity.