The Biden administration announced last week that it will recommend a third “booster” shot for Americans who have received either of the mRNA COVID-19 vaccines currently authorized for emergency use. (A recommendation for the viral vector shot developed by Johnson & Johnson, which is also available on an emergency basis in the U.S. market, will be provided at a later time, after data from its ongoing two-dose trial is assessed.) The prospect of hundreds of millions of third mRNA doses going into the arms of Americans before much of the world gets a first inoculation always was a possibility, but the recommendation to move forward came more quickly, and is broader in its reach, than many had expected. Its speed and breadth also are altering previous assumptions about the availability of excess U.S. supply for international donations.
A brief update on U.S. domestic needs and available inventory over the coming months, with the booster campaign fully included in the assessment, can clarify the options now available for further U.S. donations to the international vaccination effort. The U.S. still will be able to make a meaningful contribution to the global campaign—likely just more than 1 billion doses—but its contribution will remain far below what is required to vaccinate the worldwide population, and thus also falls well short of what would be required to substantially reduce the risk of more dangerous (and possibly vaccine-evading) variants emerging somewhere around the world.
The Current Status of Expected U.S. Consumption and Available Supply
The original Operation Warp Speed portfolio included a diversified mix of vaccine types, sponsored by six developers: the Pfizer/BioNTech collaboration, Moderna, Johnson & Johnson, Oxford/AstraZeneca, Novavax, and Sanofi/GlaxoSmithKline.
When the Phase III trials for the two mRNA candidates, from Pfizer/BioNTech and Moderna, showed them to be highly effective and very safe, the U.S. government moved quickly to make them the central pillars of its domestic vaccination campaign. To date, more than 345 million doses of the two mRNA candidates have been administered. Realistically, with the supply of the Pfizer/BioNTech and Moderna vaccines being sufficient to keep up with domestic demand, there is little prospect that any of the other candidates will get used in the U.S. market, at least during the current phase of the pandemic. A small exception is the J&J inoculation, which has been given to approximately 14 million people to date.