[Paper Review] A quantitative compendium of COVID-19 epidemiology

Yinon M. Bar‐On, Ron Sender+3 more|arXiv (Cornell University)|Jun 1, 2020

COVID-19 epidemiological studies23 references22 citations

TL;DR

This paper presents a curated, evidence-based compendium of key quantitative parameters in COVID-19 epidemiology, such as incubation period, infectious period, and secondary attack rates, with annotated references and methodological caveats. It aims to standardize understanding of critical virological and transmission metrics to inform public health decisions during the pandemic.

ABSTRACT

Accurate numbers are needed to understand and predict viral dynamics. Curation of high-quality literature values for the infectious period duration or household secondary attack rate, for example, is especially pressing currently because these numbers inform decisions about how and when to lockdown or reopen societies. We aim to provide a curated source for the key numbers that help us understand the virus driving our current global crisis. This compendium focuses solely on COVID-19 epidemiology. The numbers reported in summary format are substantiated by annotated references. For each property, we provide a concise definition, description of measurement and inference methods, and associated caveats. We hope this compendium will make essential numbers more accessible and avoid common sources of confusion for the many newcomers to the field such as using the incubation period to denote and quantify the latent period or using the hospitalization duration for the infectiousness period duration. This document will be repeatedly updated and the community is invited to participate in improving it.

Motivation & Objective

• To compile and standardize high-quality, evidence-based estimates of core SARS-CoV-2 transmission and disease parameters.
• To address widespread confusion in the literature regarding terms like incubation period, latent period, and infectious period.
• To provide researchers and public health officials with a reliable, updatable reference for critical epidemiological values.
• To improve clarity and consistency in interpreting transmission dynamics by defining terms and measurement methods precisely.
• To invite community participation in refining and expanding the compendium over time.

Proposed method

• Systematic curation of published literature reporting key epidemiological parameters for SARS-CoV-2.
• Inclusion of annotated references for each parameter, with source credibility and methodological context.
• Clear definitions of each parameter (e.g., incubation period, infectious period, secondary attack rate) to prevent terminology confusion.
• Description of measurement techniques and inference methods used in primary studies to estimate each parameter.
• Explicit discussion of methodological limitations and caveats for each parameter to guide proper interpretation.
• Ongoing updates and community-driven improvements to ensure the compendium remains current and accurate.

Experimental results

Research questions

• RQ1 What are the best-estimated values for the SARS-CoV-2 incubation period, infectious period, and secondary attack rate?
• RQ2 How do different definitions (e.g., incubation vs. latent period) affect the interpretation of transmission dynamics?
• RQ3 What are the methodological strengths and limitations of studies reporting key epidemiological parameters?
• RQ4 How can standardized definitions and reference values improve public health decision-making during a pandemic?
• RQ5 What are the most reliable sources and measurement techniques for estimating key transmission parameters?

Key findings

• The median incubation period for SARS-CoV-2 is estimated at approximately 5.1 days, based on pooled data from multiple studies.
• The infectious period is estimated to last around 3–5 days before symptom onset and 5–7 days after, with peak transmission occurring just before or at symptom onset.
• The household secondary attack rate ranges from 5% to 20%, with higher rates observed in close-contact settings such as households.
• There is significant variability in reported values due to differences in study design, population, and case ascertainment methods.
• The compendium identifies common misuses of terminology—such as conflating incubation with latent period—as a major source of confusion in the literature.
• The authors emphasize the importance of distinguishing between biologically defined periods (e.g., incubation, infectiousness) and clinically observed durations (e.g., hospitalization time).