GENEVA, Jan. 21 (CNA) - Nobody should panic about getting access to a COVID-19 vaccine because everyone who wants one will get one, the World Health Organization said on Wednesday (Jan 20).

The WHO's assistant director-general Mariangela Simao said the UN health agency was working towards ensuring access to coronavirus jabs all around the world.

"No one needs to panic, because you're going to get a vaccine," said Simao, the assistant director-general for access to medicines, vaccines and pharmaceuticals.

"We've been working very hard to ensure that all countries, all populations, do have the opportunity to access these vaccines," she told a WHO social media live event.

Simao said that around 50 countries have started vaccination campaigns, with more than 40 of them being high-income states.

The WHO co-led COVAX facility, a globally pooled vaccine procurement and distribution effort, has struck agreements with five manufacturers for 2 billion vaccine doses.

It aims to secure vaccines for 20 per cent of the population in each participating country by the end of the year, with funding covered for the 92 lower- and lower-middle income economies involved.

"We are expecting to have the first doses reaching countries end of February," Simao said.

According to the WHO's overview of candidate vaccines, 64 have been tested on humans, 22 of which have reached final-stage mass testing.

A further 173 candidate vaccines are being developed in laboratories with a view to eventual human trials.

WHO chief scientist Soumya Swaminathan welcomed the "really incredible" range, saying it was important to have a variety of vaccines with different properties.

So far, the WHO has only approved emergency use validation for the two-dose Pfizer-BioNTech vaccine, which requires ultra-cold storage.