India’s export ban on Covid-19 shots risks dragging the battle against the pandemic “back to square one” unless wealthy nations step in to plug a gaping hole in the COVAX global vaccine-sharing scheme, health specialists said on May 20.

The same group at the University of Oxford and the Jenner Institute that developed the AstraZeneca-Oxford Covid-19 vaccine reported that their investigational malaria vaccine, R21/Matrix-M, demonstrated 77 percent efficacy in children over 12 months of follow-up.

COVAX will deliver 237 million doses of AstraZeneca’s Covid-19 shot to 142 countries by the end of May as the World Health Organization-backed program steps up the global roll-out of its vaccine supplies.

Many health experts believe that the Covid-19 vaccine candidate NVX-CoV237 from Novavax offers potential advantages over competitors including Pfizer-BioNTech, Moderna, Johnson & Johnson, and AstraZeneca-Oxford.

Drug developer Novavax Inc. completed enrolling 30,000 volunteers in a late-stage study of the company’s Covid-19 vaccine in the United States and Mexico.

The World Health Organization (WHO) on Feb. 15 listed AstraZeneca and Oxford University’s Covid-19 vaccine for emergency use, widening access to the relatively inexpensive shot in the developing world.

AstraZeneca is likely to run an additional global trial to assess the efficacy of the company’s Covid-19 vaccine using a lower dosage, the British drugmaker’s chief executive was quoted as saying amid questions over the results of a late-stage study.

Although it’s increasingly likely that one of the Covid-19 vaccines being tested will be approved or receive Emergency Use Authorization (EUA) before the end of 2020, experts are increasingly warning that widespread distribution may take a much longer time.