The World Health Organisation (WHO) on New Year's first day granted emergency use validation for the Pfizer-BioNTech COVID-19 vaccine, opening the door for nation to expedite their own regulatory approval processes to import the vaccine.

While many countries rely on their own regulatory systems for vaccine approvals, some countries with weak system depend on WHO's nod to a great extent for rolling out their national vaccination programmes.

The WHO's emergency validation also enables Unicef and the Pan-American Health Organization to procure the vaccine for distribution to countries in need, the UN health agency said on Thursday.

Several nations including the US and the UK have already approved the Covid-19 vaccine of Pfizer.

This is the first time the international has granted emergency validation to a vaccine since the crisis began.

Mariangela Simao, WHO Assistant-Director General for Access to Medicines and Health Products, in a statement said,

"This is a very positive step towards ensuring global access to Covid-19 vaccines. But I want to emphasise the need for an even greater global effort to achieve enough vaccine supply to meet the needs of priority populations everywhere."

The WHO noted that the vaccine requires storage using an ultra-cold chain -- it needs to be stored at minus 60 degree C to minus 90 degree C.

This requirement makes the vaccine more challenging to deploy in settings where ultra-cold chain equipment may not be available or reliably accessible.

For that reason, WHO is working to support countries in assessing their delivery plans and preparing for use where possible.

(With inputs from IANS)