Prime Minister Boris Johnson has said it is "excellent news" that a third coronavirus vaccine has been approved for use in the United Kingdom.
Alejandro Cravioto, chairman of WHO's Strategic Advisory Group of Experts on Immunisation (SAGE), told media persons during a news briefing that two doses are needed to make the vaccine more effective.
There are hundreds still in development, with some expected to report findings in the near future.
The Philippines can soon procure up to 20 million doses of COVID-19 vaccines from American pharmaceutical company Moderna - a result of months of negotiations, an envoy announced Wednesday.
That figure includes nearly a quarter of those aged over 80 in England - people at highest risk of severe illness or death from the virus.
Overall, some 2.9 million people have been infected in the UK.
Health Secretary Matt Hancock said the approval of the Moderna jab by the Independent Medicines and Healthcare products Regulatory Agency (MHRA) was another shot in the arm for the programme.
France is seeking to vaccinate a million people before the end of January, to speed up a process which got off to a slow start. Message boards on the so-called dark web have added COVID-19 vaccines to more traditional illicit goods for sale.
Both vaccines now authorized in the USA, developed by Pfizer and Moderna, require recipients to receive booster shots after three and four weeks, respectively.
The AstraZeneca jab is easier to store and distribute, as it can be kept at normal fridge temperature.
The doses would be available to member states in the second quarter of this year.
On dark web forum Agartha, fake COVID-19 vaccines were offered next to cocaine, opioid medication, "super high quality fake money", hand guns and gift cards. For all of the Covid vaccines, we still do not know how long immunity will last.
The U.S. Federal Bureau of Investigation and Interpol, among others, have warned of emerging pandemic-related fraud schemes, saying false cures and vaccines advertised on fake websites could pose cyber threats and a significant risk to peoples' health, or even lives.
The move would allow European Union governments to double their orders from Pfizer to 600 million doses, commission president Ursula von der Leyen said, as the 27-nation bloc races to ramp up the vaccination of its 450 million people.