The FDA-authorized COVID-19 vaccine from Moderna and Pfizer require two doses for full immunity, but healthcare officials are weighing whether to delay the second doses or to halve the recommended dose in order to reach more people.

Operation Warp Speed chief adviser Moncef Slaoui said there is evidence that two half doses in people between the ages of 18 and 55 gives “identical immune response” to the recommended one hundred micorogram dose, but said the final decision will rest with the FDA.


According to Reuters, the CDC reports 4,225,756 first doses of COVID-19 vaccines have been administered in the US and (as of Saturday morning) and 13,071,925 doses have been delivered.

There are an estimated 331 million people living in the United States.

Former FDA Commissioner Scott Gottlieb on Monday told CNBC that administering one dose to the younger cohort, which are typically more resilient against the virus, would “certainly extend the supply.”


Meanwhile, UK health officials are delaying the second recommended dose of their available vaccines in order to inoculate more people.

Health experts have conditionally backed the UK’s decision to delay administering a second dose of the coronavirus vaccine developed by Pfizer and BioNTech, warning that the need to suppress the new coronavirus strain “cannot be overstated.” It comes shortly after the UK said second doses of the Pfizer-BioNTech jab, in addition to the newly-approved COVID-19 vaccine developed by AstraZeneca and the University of Oxford, would now be given up to 12 weeks after the first dose.