Estimating the percentage of a population infected with SARS‐CoV‐2 using the number of reported deaths: A policy planning tool

Daniel R. Feikin, Marc Alain Widdowson, Kim Mulholland

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


The magnitude of future waves of Covid19 in a population will depend, in part, on the percentage of that population already infected, recovered, and presumably immune. Sero-epidemiological surveys can define the prevalence of SARS‐CoV‐2 antibodies in various populations. However, sero‐surveys are resource‐intensive and methodologically challenging, limiting widespread use. We propose a relatively simple method for calculating the percentage of a population infected, which depends on the number of reported Covid19 deaths, a figure usually more reliable and less dependent on variable testing practices than the total number of reported Covid19 cases, and the infection fatality rate, a figure that is relatively stable in similar populations. The method can be applied in different sized areas, such as states, districts, or cities. Such an approach can provide useful, real‐time estimates of probable population immunity in settings unable to undertake multiple sero‐surveys. This method is applicable to low‐ and lower‐middle-income country (LMIC) settings where sero‐survey data will likely be limited; however, better estimates of infection fatality rates and Covid19 death counts in LMICs are needed to improve the method’s accuracy. Information on the percentage of a population infected will help public health authorities in planning for future waves of Covid19, including where to most effectively deploy vaccines.

Original languageEnglish (US)
Article number838
Pages (from-to)1-12
Number of pages12
Issue number10
StatePublished - Oct 2020


  • Coronavirus
  • Covid19
  • Low‐ and middle‐income countries
  • SARS‐CoV‐2
  • Serology
  • Sero‐prevalence

ASJC Scopus subject areas

  • Immunology and Allergy
  • Molecular Biology
  • General Immunology and Microbiology
  • Microbiology (medical)
  • Infectious Diseases


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