A Half Dose of Moderna is More Effective Than a Full Dose of AstraZeneca
Today we are releasing a new paper on dose-stretching co-authored by Witold Wiecek, Amrita Ahuja, Michael Kremer, Alexandre Simoes Gomes, Christopher M. Snyder, Brandon Joel Tan and myself.
The paper makes three big points. First, Khoury et al (2021) just published a paper in Nature which shows that “Neutralizing antibody levels are highly predictive of immune protection from symptomatic SARS-CoV-2 infection.” What that means is that there is a strong relationship between immunogenicity data that we can easily measure with a blood test and the efficacy rate that it takes hundreds of millions of dollars and many months of time to measure in a clinical trial. Thus, future vaccines may not have to go through lengthy clinical trials (which may even be made impossible as infections rates decline) but can instead rely on these correlates of immunity.
Here is where fractional dosing comes in. We supplement the key figure from Khoury et al.’s paper to show that fractional doses of the Moderna and Pfizer vaccines have neutralizing antibody levels on par with those of many approved vaccines. Indeed, a one-half or one-quarter dose of the Moderna or Pfizer vaccine looks to be more effective than the standard dose of some of the other vaccines like the AstraZeneca, J&J or Sinopharm vaccines. The point is not that these other vaccines aren’t good–they are great! The point is that by using fractional dosing we could rapidly and safely expand the number of effective doses of the Moderna and Pfizer vaccines.
