International Evidence on Vaccines and the Mortality to Infections Ratio
Recent observations on countries like the UK that have accumulated a large fraction of inoculated individuals suggest that, although initially, vaccines have little effect on new infections they strongly reduce the share of mortality out of a given pool of infections. This paper examines the extent to which this phenomenon is more general by testing the hypothesis that the ratio of current mortality to lagged infections is decreasing in the total number of vaccines per one hundred individuals. This is done in a pooled time-series, cross-section sample with weekly observations for up to 208 countries. The main conclusion from the statistical analysis is that, passed a certain threshold, vaccines moderate the share of mortality from a given pool of lagged infections. This is essentially a favorable shift in the tradeoff between life preservation and economic performance. Controlling for income per capita, stringency of containment measures, and the fraction of recovered and old individuals, estimation is carried out by linear least squares, with standard errors clustered by country and region. The main result is robust to sensitivity analysis with a logarithmic specification. The practical lesson is that, in the presence of a sufficiently high share of inoculated individuals, governments can shade down containment measures, even as infections are still rampant, without significant adverse effects on mortality.
Joshua Aizenman is grateful for the support provided by the Dockson Chair in Economics and International Relations, USC. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research, the Asian Development Bank, and the International Monetary Fund.