Viral Disease: Transmissibility vs Severity

Viral Disease: Transmissibility vs. Severity

Case fatality rate (log scale) vs. basic reproduction number (R₀)

Vaccine Available

No Vaccine Currently

• High R₀ ≠ High Severity: Measles is highly transmissible but has relatively low CFR
• Low R₀ ≠ Low Threat: MERS and Ebola spread slowly but are highly lethal
• Vaccines target high R₀ diseases: Most vaccine-preventable diseases have R₀ > 5
• Pandemic potential: Combines moderate-high R₀ with significant CFR (see influenza 1918, COVID-19)

R₀ Estimates:

• Guerra FM, et al. "The basic reproduction number (R₀) of measles: a systematic review." Lancet Infect Dis. 2017;17(12):e420-e428. doi:10.1016/S1473-3099(17)30307-9
• Biggerstaff M, et al. "Estimates of the reproduction number for seasonal, pandemic, and zoonotic influenza: a systematic review of the literature." BMC Infect Dis. 2014;14:480. doi:10.1186/1471-2334-14-480
• Delamater PL, et al. "Complexity of the Basic Reproduction Number (R₀)." Emerg Infect Dis. 2019;25(1):1-4. doi:10.3201/eid2501.171901
• Liu Y, et al. "The reproductive number of COVID-19 is higher compared to SARS coronavirus." J Travel Med. 2020;27(2):taaa021. doi:10.1093/jtm/taaa021

Case Fatality Rate (CFR) Estimates:

• World Health Organization. Disease Outbreak News. https://www.who.int/emergencies/disease-outbreak-news
• CDC. Vaccines and Preventable Diseases. https://www.cdc.gov/vaccines/vpd/
• Verity R, et al. "Estimates of the severity of coronavirus disease 2019: a model-based analysis." Lancet Infect Dis. 2020;20(6):669-677. doi:10.1016/S1473-3099(20)30243-7
• Garske T, et al. "Yellow Fever in Africa: estimating the burden of disease and impact of mass vaccination." PLoS Med. 2014;11(5):e1001638. doi:10.1371/journal.pmed.1001638

General Epidemiology References:

• Fine P, Eames K, Heymann DL. "Herd immunity: a rough guide." Clin Infect Dis. 2011;52(7):911-916. doi:10.1093/cid/cir007
• Anderson RM, May RM. Infectious Diseases of Humans: Dynamics and Control. Oxford University Press; 1991.
• Vynnycky E, White R. An Introduction to Infectious Disease Modelling. Oxford University Press; 2010.

Vaccine Information:

Important Notes:

• CFR values vary significantly by healthcare access, population demographics, virus strain, and treatment availability
• R₀ estimates depend on population density, behavior, immunity levels, and environmental factors
• Values represent typical ranges from published literature; individual outbreaks may differ
• Some "no vaccine" diseases have experimental vaccines in development or limited-use vaccines
• CFR ≠ Infection Fatality Rate (IFR); CFR only includes confirmed/symptomatic cases

Created for Biomedical Engineering Course | Last Updated: February 2026