THE World Health Organization (WHO) and global vaccine charities launched the COVAX programme last April to distribute COVID-19 vaccines to some of the world's poorest people.

The scheme, relied on by dozens of poorer countries, has faced setbacks: production glitches, a lack of support from wealthy nations and a recent move by India, the biggest vaccine manufacturer, to curb its exports.

Besides the WHO, it is run by the Global Alliance for Vaccines and Immunization (GAVI), Coalition for Epidemic Preparedness Innovations (CEPI) and U.N. Children's Fund (UNICEF).

Here's a look at progress since its inception:

APRIL 24, 2020:

The WHO, European Commission and the Bill & Melinda Gates Foundation launch an initiative known as the ACT (Access to COVID-19 Tools) Accelerator. COVAX is the part that focuses on vaccines.

JUNE 4, 2020:

COVAX raises $567 million towards an initial goal of $2 billion from international donors.

JULY 15, 2020:

More than 75 countries show interest in joining the scheme.

JULY 31, 2020:

The WHO urges countries to support COVAX, says countries that back it have a better chance of getting a successful COVID-19 vaccine.

AUG. 18, 2020:

WHO chief Tedros Adhanom Ghebreyesus warns that countries putting their own interests ahead of others to ensure supplies of a possible vaccine are making the pandemic worse.

AUG. 24, 2020:

Some 172 countries join COVAX. WHO says more funding is urgently needed and countries should make binding commitments.

AUG. 28, 2020:

Wealthier countries are offered a new option under COVAX to pick and choose which shots they get, in a move aimed at convincing governments that have bilateral deals to sign up to the facility.

SEPT. 4, 2020:

WHO says 78 high-income countries confirm participation ahead of Sept. 18 deadline for signing up.

SEPT. 17, 2020:

WHO says more than 170 countries have joined COVAX. EU nations offer funds but decline to buy vaccines through COVAX for themselves.

United States and Russia don't join.

OCT. 8, 2020:

China says it will purchase COVAX vaccines for 1% of its population.

OCT. 19, 2020:

WHO says 184 countries have signed up for COVAX.

NOV. 12, 2020:

EU increases contribution to COVAX to 500 million euros. ($601 million).

NOV. 13, 2020:

GAVI raises $2 billion to buy COVID-19 shots for COVAX.

NOV. 22, 2020:

German Chancellor Angela Merkel urges COVAX to start talks immediately with vaccine makers.

DEC. 4, 2020:

WHO hopes to have half a billion vaccine doses available for distribution by COVAX in Q1 2021.

DEC. 15, 2020:

The European Union considers plan to donate 5% of the COVID-19 vaccines it has secured to poorer nations.

DEC. 18, 2020:

COVAX doubles global vaccine supply deals to 2 billion doses and aims to deliver 1.3 billion doses in 2021 to 92 eligible low- and middle-income economies.

JAN. 7, 2021:

WHO says poorer nations could start receiving vaccines from COVAX as soon as January, after the programme raises $6 billion of the $7 billion that it has sought in 2021 to help finance deliveries.

JAN. 8, 2021:

WHO's Tedros urges countries to stop striking bilateral deals with manufacturers and release extra doses to COVAX immediately, as the EU agrees a supply deal for hundreds of millions of doses of the Pfizer-BioNTech vaccine.

The United States, Britain and Canada have also reserved large volumes of vaccines.

JAN. 18, 2021:

WHO chief Tedros says vaccine nationalism puts world on brink of "catastrophic moral failure" and could delay COVAX deliveries.

WHO says it is in talks with Pfizer about including its vaccine in COVAX.

JAN. 19, 2021:

European Union eyes its own scheme to share surplus vaccines with poorer neighbouring states and Africa before COVAX is fully operational.

JAN. 20, 2021:

Chinese vaccine makers - Sinovac Biotech, China National Pharmaceutical Group (Sinopharm) and CanSino Biologics - apply to join COVAX.

JAN. 21, 2021:

U.S. infectious disease official Anthony Fauci says United States intends to join COVAX.

Pfizer and BioNTech agree to supply 40 million doses of their vaccine to COVAX.

JAN. 29, 2021:

WHO says COVAX will ship enough shots for 3% of poor countries' populations in first half of 2021.

FEB. 3, 2021:

China says it will provide 10 million doses of COVID-19 vaccines to COVAX.

India's Serum Institute signs new long-term deal to supply 1.1 billion doses of vaccines developed by AstraZeneca and Novavax to COVAX.

FEB. 5, 2021:

WHO says COVAX initiative aims to start shipping nearly 90 million COVID-19 vaccine doses to Africa in February.

FEB. 15, 2021:

WHO approves AstraZeneca/Oxford COVID-19 vaccine for emergency use. South Korea scales back initial vaccination targets due to delayed COVAX shipments.

FEB. 18, 2021:

The United States announces $4 billion funding for COVAX, of which $2.5 billion is for this year.

FEB. 19, 2021:

EU doubles contribution to COVAX with additional 500 million euros.

Johnson & Johnson applies to WHO for emergency use listing of COVID-19 vaccine, a prerequisite for supplying vaccines to COVAX.

FEB. 22, 2021:

WHO agrees a no-fault compensation plan for claims of serious side effects in people in 92 poorer countries getting vaccines via COVAX.

FEB. 24 and 26, 2021:

First COVID-19 vaccine doses via COVAX arrive in Ghana and Ivory Coast.

FEB. 26, 2021:

WHO says countries seeking their own vaccine doses threaten COVAX supplies.

MARCH 2, 2021:

Nigeria and Cambodia receive first COVID-19 vaccines under COVAX.

WHO says COVAX is expected to deliver 237 million doses of AstraZeneca's vaccine to 142 countries by end of May.

MARCH 5, 2021:

Moldova is first European country to receive COVID-19 vaccines under COVAX.

WHO's Tedros says COVAX has supplied more than 20 mln doses to 20 countries.

MARCH. 12, 2021:

WHO approves J&J's COVID-19 vaccine for emergency listing.

MARCH 24, 2021:

India puts a temporary hold on exports of AstraZeneca shot made by the Serum Institue of India to meet domestic demand.[nL1N2LM3IG]

Serum had been due to deliver 90 million doses of vaccine to COVAX in March and April.

APRIL 1, 2021:

WHO's Tedros says the facility faces a "serious challenge" to meet demand, requesting manufacturers help ensure that the countries that step up can rapidly donate those doses.

APRIL 8, 2021:

WHO says COVAX has delivered nearly 38.4 million doses of COVID-19 vaccines to 102 countries and economies across six continents. The facility aims to supply at least 2 billion doses this year.

APRIL 15, 2021:

United Nations officials appeal for another $2 billion by June for COVAX.