London: A large UK study showed that Vaccines against Covid-19 are less effective against the delta variant. The results are likely to fuel calls to give booster shots to the fully vaccinated even as countries around the world still lack enough supply for first immunizations.
The US on Wednesday said Americans who got both doses of the Pfizer-BioNTech or Moderna Inc. mRNA vaccine will be able to get a third one after eight months. UK authorities are still deciding how broadly boosters should be given.
In Israel, which started giving third doses of Pfizer-BioNTech this month, initial results show they have been 86% effective for people over the age of 60.
The UK survey, run by the University of Oxford and the Office for National Statistics and published Thursday in a preprint, analyzed more than 3 million PCR tests from a random sample of people for a detailed picture of infection patterns as delta became the dominant variant this year.