Using COVID-19 deaths as a surrogate to measure the progression of the pandemics.

HERNANDEZ-SUAREZ, C. M.; Murillo-Zamora, E.

The IFR (Infection Fatality Risk) is one of the most important parameters of an infectious disease. If properly estimated, the observed number of deaths divided by the IFR can be used to estimate the current number of infections and, if immunity is permanent, we can estimate the fraction of susceptible which can be used to plan reopening of activities and vaccine deployment, when these become available. Here we suggest how to use the observed deaths by COVID-19 in an arbitrary population as a surrogate for the progression of the epidemic with the purpose of decision making. We compare several estimates of IFR for SARS-CoV-2 with our estimate that uses the number of additional deaths in households in a database population of 159,150 laboratory-confirmed (RT-qPCR) COVID-19 by SARS-COV-2 in Mexico. The main result is that if the number of deaths in a region is close to 2 per thousand individuals, the fraction of remaining susceptible may be too small for the vaccine to make a difference in the total number of infected.