How some vaccines are helping nations to exit Covid faster than others

 Messenger RNA shots developed by Moderna or Pfizer and BioNTech are better at stopping people from becoming contagious, shows evidence.

With hundreds of millions of people now vaccinated against Covid-19, the coronavirus outbreak should begin to die down in places where a large chunk of the population has been inoculated. But that isn’t happening everywhere. Instead, two paths are emerging: In countries such as Israel, new Covid cases are declining as vaccinations spread, while in other places like the Seychelles — which has fully inoculated more of its population than any other nation — infections continue to increase or even reach new highs.

One reason for that may be the different types of vaccine being used. Evidence derived from the expanding global inoculation rollout indicates that the messenger RNA shots developed by Moderna Inc. or Pfizer Inc. and BioNTech SE are better at stopping people from becoming contagious, helping reduce onward transmission — an unexpected extra benefit as the first wave of Covid vaccines were intended to stop people from becoming very sick.

Other vaccines, while effective in preventing acute illness or death from Covid, appear not to have this extra perk to the same degree. “This will be an increasing trend as countries start to realize that some vaccines are better than others,” said Nikolai Petrovsky, a professor at the College of Medicine and Public Health at Flinders University in South Australia. While the use of any vaccine “is still better than nothing,” he said, some doses “may have little benefit in preventing spread, even if they reduce the risk of death or severe disease.”