How Many Vaccines Do We Need?

At Bloomberg Sam Fazell asks an interesting question: how many COVID-19 vaccines do we need, anyway?

On paper, the U.S. has signed up for more vaccine doses than it needs for its whole population. The issue is that these deals were all done before we had any idea of the relative efficacy of the vaccines. The U.S. will have 300 million doses – 100 million from Pfizer-BioNTech and 200 million from Moderna – at its disposal through the first half of 2021. This is enough for 150 million people, or half the U.S. population, assuming no wastage, because each vaccine requires two shots. While this does not fit with the promise of getting most of the U.S. vaccinated by the middle of next year, it is probably much more realistic, given the massive logistical issues involved and the continuing hesitancy of some people. There will be other vaccine trial results coming out very soon too, and that may lead to more candidates being authorized for use. AstraZeneca’s and J&J’s U.S. trials will be done early in the first quarter, while Novavax will have its large U.K. trial data in the same time frame.

My answer to the question is that we need at least one more, possibly two. We need one vaccine that does not rely on mRNA but on modalities with which we have experience and we need one that uses materials that are different from those used by either Pfier or Moderna. It’s quite possible that although Pfizer and Moderna’s internal projects say that they can produce a total of 300 million doses in reality they can’t reach that many for supply chain reasons.