Dr Anthony Fauci has said a study that sought to determine which Covid-19 vaccine is more effective against the Delta variant has not gone through the right reviews yet.

       The chief medical adviser to President Joe Biden and director for the National Institute of Allergy and Infectious Diseases appeared on CBS’ Face the Nation and discussed the differences between the Moderna and Pfizer vaccines, along with the problems caused by the surge in coronavirus cases.

       When asked about booster shots for vulnerable people, CBS’ Nancy Cordes cited a preliminary study that said the Pfizer vaccine was 42 per cent likely to reduce transmission of the Delta variant compared to 76 per cent for Moderna.

       Dr Fauci said the study, conducted by the Mayo Clinic, was “preprint” and needed to be “fully peer-reviewed” before its findings could be more widely accepted.

       He continued, “I don’t doubt what they’re seeing, but there are a lot of confounding variables in there, about when one was started, the relative amount of people in that cohort who were Delta vs Alpha.”

       The study, which used data from 25,000 Minnesotans, was conducted by looking at samples of people who were infected with the Delta variant of the coronavirus and the type of vaccine they received.

       Currently, there are three vaccines authorised for use in the US. Pfizer and Moderna have manufactured a vaccine each that requires two doses to be deemed fully vaccinated. Johnson & Johnson created a jab that only requires a single dose.

       The Centers for Disease Control and Prevention has released data that showed vaccinated people can still pass on the virus, despite having less severe infections.

       According to Dr Fauci, there are 90 million people who are able to get vaccinated but have not yet, and he urged the importance of doing so.

       According to data from The New York Times, 50 per cent of eligible US residents are deemed to be fully vaccinated against the coronavirus.