New research by a team at the MIT Sloan School of Management estimates that COVID-19 cases and deaths are 12 times and 1.5 times higher than official reports, respectively. The study examined 84 of the most affected nations, spanning 4.75 billion people. The researchers estimate 88.5 million cases and 600 thousand deaths through June 18, 2020.
Despite substantial under-reporting, however, these nations remain well below the level needed for herd immunity. Absent breakthroughs in treatment or vaccines, and with only mild improvements in policies to control the pandemic, the researchers estimate a total of 249 million (186-586) cases and 1.75 million (1.40-3.67) deaths by Spring 2021.
Earlier and stronger policies to reduce transmission when the pandemic was first declared, together with the deployment of extensive testing, could have averted approximately 197,000 deaths, nearly one third of the estimated total.
However, they say, future cases and deaths are now less dependent on testing and more contingent on the willingness of communities and governments to reduce transmission, such as by reducing contacts with others, physical distancing, and better hygiene, including masks.
The nations with the highest estimated percentage of their populations infected to date include Ecuador (18%), Peru (16.6%), Chile (15.5%), Mexico (8.8%), Iran (7.9%), Qatar (7.3%), Spain (7.1%), USA (5.3%), UK (5.2%), and the Netherlands (4.8%).
The paper, Estimating the Global Spread of COVID-19, is co-authored by MIT Sloan’s Hazhir Rahmandad, Associate Professor of System Dynamics; Professor John Sterman, Director of the MIT Systems Dynamics Group; and Ph.D. candidate Tse Yang Lim.
Using data for all 84 countries with reliable testing data (spanning 4.75 billion people), they developed a dynamic epidemiological model integrating data on cases, deaths, excess mortality and other factors to estimate how asymptomatic cases, disease acuity, hospitalization, and behavioral and policy responses to risk affect COVID transmission and the Infection Fatality Rate (IFR)—the probability of death after becoming infected—across nations and over time. IFR depends not only on the age and health of the population, but on the adequacy of health care and the effectiveness of protections for the most vulnerable, including the elderly. The researchers estimate IFR to be 0.68% on average (0.64%-0.7%), but find it varies substantially across nations: approximately 0.56% for Iceland, 0.64% New Zealand, 0.99% for the USA, 1.59% for the UK, and 2.08% for Italy.