A World Health Organization spokeswoman said on Friday it does not expect widespread vaccinations against COVID-19 until the middle of next year, stressing the importance of rigorous checks on their effectiveness and safety.
"We are not expecting to see widespread vaccination until the middle of next year," spokeswoman Margaret Harris told journalists at a briefing in Geneva.
"This Phase 3 must take longer because we need to see how truly protective the vaccine is and we also need to see how safe it is," she added referring to vaccine clinical trials.
Three Western drug makers are progressing with their Phase 3 clinical trials, involving tens of thousands of participants.
The three are AstraZeneca, which is partnering with Oxford University in England; Moderna, collaborating with the US National Institutes of Health; and the Pfizer/BioNTech alliance.
By the nature of the trials, it is difficult to predict when reliable results will emerge.
Half of the participants in such trials receive an experimental vaccine, while the other half are given a placebo.
Under normal procedures, test administrators must wait -- probably for months -- to see whether there is a statistically significant difference in the infection rate of the two groups.
The US Food and Drug Administration however has raised the possibility that a vaccine might be given emergency approval before the end of trials.
