The UN Security Council is voting on a British-drafted resolution that demands that all parties to armed conflicts "engage immediately in a durable, extensive, and sustained humanitarian pause" to allow for COVID-19 vaccinations.
The likely adoption of the draft resolution - diplomats said they expect it to pass - is a key test of cooperation at the United Nations between China and new US President Joe Biden's administration.
The 15-member Security Council took more than three months to back a call by Secretary-General Antonio Guterres for a global pandemic ceasefire last year due to bickering between China and former US President Donald Trump's administration.
Under pandemic procedure, council members have 24 hours to vote in writing. The result will be announced on Friday. A resolution needs nine votes in favor and no vetoes by the United States, Russia, France, Britain or China to be adopted.
The draft resolution expresses its intention to review specific situations raised by Guterres where COVID-19 vaccination is being impeded and to "consider what further measures may be necessary to ensure such impediments are removed and hostilities paused to enable vaccination".
It also asks developed countries to donate vaccine doses to low and middle-income countries and other nations in need, particularly through the COVAX vaccine sharing facility.
This is co-led by by the GAVI alliance, which secures vaccines for poor countries, the World Health Organization, the Coalition for Epidemic Preparedness Innovations and the UN Children's Fund.
The draft resolution "calls for the strengthening of national and multilateral approaches and international cooperation ... in order to facilitate equitable and affordable access to COVID-19 vaccines in armed conflict situations, post-conflict situations and complex humanitarian emergencies".
It would also stress the need for international partnerships to scale up manufacturing and distribution capabilities.