Working Paper: CEPR ID: DP16324
Authors: Witold Wicek; Amrita Ahuja; Michael Kremer; Alexandre Simoes Gomes Junior; Christopher Snyder; Alex Tabarrok; Brandon Tan
Abstract: We argue that alternative COVID-19 vaccine dosing regimens could potentially dramatically accelerate global COVID-19 vaccination and reduce mortality, and that the costs of testingthese regimens are dwarfed by their potential benefits. We first use the high correlation betweenneutralizing antibody response and efficacy against disease (Khoury et. al. 2021) to show thathalf or even quarter doses of some vaccines generate immune responses associated with high vaccine efficacy. We then use an SEIR model to estimate that under these efficacy levels, doublingor quadrupling the rate of vaccination by using fractional doses would dramatically reduce infections and mortality. Since the correlation between immune response and efficacy may not be fullypredictive of efficacy with fractional doses, we then use the SEIR model to show that fractionaldosing would substantially reduce infections and mortality over a wide range of plausible efficacylevels. Further immunogenicity studies for a range of vaccine and dose combinations could deliver outcomes in weeks and could be conducted with a few hundred healthy volunteers. Nationalregulatory authorities could also decide to test efficacy of fractional dosing in the context of vaccination campaigns based on existing immune response data, as some did for delayed second doses.If efficacy turned out to be high, the approach could be implemented broadly, while if it turned outto be low, downside risk could be limited by administering full doses to those who had receivedfractional doses. The SEIR model also suggests that delaying second vaccine doses will likely havesubstantial mortality benefits for multiple, but not all, vaccine-variant combinations, underscoringthe importance of ongoing surveillance. Finally, we find that for countries choosing between approved but lower efficacy vaccines available immediately and waiting for mRNA vaccines, usingimmediately available vaccines typically reduces mortality.
Keywords: vaccine; pandemic; epidemiology; public health; supply chains
JEL Codes: No JEL codes provided
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| reduced dosing (Y60) | maintained efficacy (C22) |
| delaying second vaccine doses (C41) | substantial mortality benefits (J17) |
| using lower efficacy vaccines (I18) | reduced mortality (I14) |
| fractional dosing (Y60) | reduced infections (I14) |
| fractional dosing (Y60) | reduced mortality (I14) |
| vaccination rate (I14) | public health outcomes (I14) |