LONDON - A coronavirus vaccine that has proved 90% effective after early trials has raised hopes that the global pandemic can be brought under control in the coming months.
But the nature of the vaccine means that less developed health systems face major challenges rolling out any inoculation programs.
Developed jointly by pharmaceutical firms Pfizer and BioNTech, the vaccine is undergoing Phase 3 trials. More than 40,000 people across three continents were recruited for the trial, with half given the vaccine and half a placebo.
Several weeks on, 94 individuals were infected with the coronavirus over the trial period through natural exposure in the community. Exact figures have not yet been released, but the developers say by far the majority of those infected had been given the placebo, suggesting the vaccine is around 90% effective.
Pfizer CEO Albert Bourla released a statement Tuesday saying, "The data demonstrated that the study vaccine can prevent COVID-19 disease in adults who have not previously been diagnosed with COVID-19. This is a great victory for humanity, and one that could not have been accomplished without the almost 44,000 people who selflessly raised their hands to participate in our trial and help our scientists and clinicians advance this important breakthrough."
BioNTech's co-founder and CEO Ugur Sahin said he was optimistic the protective effect of the vaccine would last for at least a year. At least two injections would be required to achieve that level of immunity.
The developers have pledged to price the vaccine at below market rates and to differentiate pricing between countries or regions.
The vaccine is based on new so-called "mRNA" technology and is yet to be approved by regulators. Even if that approval is fast-tracked, there are other hurdles, noted Dr. Peter Drobac, a global public health expert at the University of Oxford.
"There are big manufacturing challenges. There are logistics challenges. This vaccine needs to be stored at minus 80 degrees Celsius," Drobac told VOA.
Such storage conditions are feasible in richer nations. In poorer countries with less developed health systems, rolling out a coronavirus vaccination program will be much more difficult. The United Nations said health systems serving two-thirds of the world's population do not have adequate refrigeration facilities.
Jean-Claude Mubalama, head of health and nutrition at the United Nations Children's Fund (UNICEF), said the capacity simply does not exist.
"So, if today we had to vaccinate against the coronavirus, for example, we would need a lot more refrigerators to keep the vaccines. We don't have these fridges," Mubalama told The Associated Press last month.
Then there is the problem of power.
"The hot climate means that the cooling devices are more important and have to work harder," said Toby Peters, a professor in cold economy at Britain's University of Birmingham. "It's a lack of electricity. It's developing economies. So, if you look in a number of these markets, you can find countries ... where perhaps 30 or 40% of the health centers don't have access to electricity."
UNICEF spent $85 million in 2019 on refrigeration equipment, mostly solar-powered refrigerators in Africa and Asia. It is also stockpiling syringes and developing cold-chain storage and transportation ahead of any vaccine approval.
An added challenge is getting people to clinics or visiting them in the community - and persuading them the vaccine is safe.
Drobac said there is a danger of "vaccine nationalism," where rich countries buy up all the available vaccines for their own populations. Over 150 countries have signed up to a global facility called COVAX to ensure equitable distribution ... "with the goal being to help produce 2 billion doses of various COVID vaccines that could be distributed to all of these countries around the world by the end of 2021," Drobac told VOA.
He added that COVAX will be vital once a vaccine is approved, because "no one is safe until everyone is safe" from the virus.
Scientists say the success of the Pfizer-BioNTech vaccine suggests other coronavirus vaccines currently going through trials could also prove effective, boosting hopes of large-scale inoculation programs.
They warn, however, that until such programs are rolled out, it is vital that governments and individuals continue to try to suppress the spread of the virus, as global infection rates continue to soar.