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Key Terms

• 1918 influenza: A pandemic that infected one-third of the global population, causing millions of deaths.

• Aerosols: Tiny droplets that can spread pathogens over long distances.

• Antibody test: Blood test detecting previous infections by measuring antibodies.

• Asymptomatic: Virus carriers without symptoms, complicating identification efforts.

• Basic reproduction number (R0): Average secondary infections caused by one infected individual.

• Case fatality rate (CFR): Death proportion from a disease against diagnosed cases.

• Challenge trials: Studies where volunteers are infected to evaluate treatments.

• Contact tracing: Identifying individuals exposed to an infectious agent.

• COVID-19: Disease caused by SARS-CoV-2, identified in December 2019.

• Crowd-epidemic diseases: Rapidly spreading diseases in crowded populations.

• Dispersion factor: Quantifies case distribution in a population.

• Effective reproduction number (Rt): Estimates secondary infections based on control measures.

• Excess mortality: Deaths exceeding expected historical figures during an epidemic.

• Face mask: Covering to reduce respiratory virus transmission.

• False negatives: Tests that miss detecting an infection.

• Fomite-mediated transmission: Pathogen spread via contaminated surfaces.

• Gain-of-function research: Enhancing virus infectiousness for study purposes.

• Herd immunity: Indirect protection when a large portion of a population is immune.

• Incubation period: Time from virus exposure to symptom onset.

• Infection fatality rate (IFR): Death rate among infected individuals, including all cases.

• Mitigation: Strategies to lessen epidemic severity, like social distancing.

• Pandemic: Disease outbreak spreading globally.

• Respiratory droplets: Droplets disseminated during coughing, sneezing, etc.

• SARS-CoV-2: Virus causing COVID-19, first found in Wuhan.

• SIR epidemic model: Mathematical model dividing a population into susceptible, infected, and recovered groups.

• Social distancing: Maintaining physical distance to curb transmission.

• Superspreading: One infected person transmitting the virus to many others.

• Suppression: Strategies to reduce infections to nearly zero.

• Symptomatic: Individuals showing illness signs, crucial for identifying transmission sources.

• Three Cs: High-risk environments for COVID-19 transmission include crowded places, close contact settings, and confined spaces.

• Morbidity: The state of being diseased or unhealthy.

• Trace-and-test program: Identification and testing initiative for potential disease exposure.

• Transmission: Passing disease from one individual to another.

• Vaccine: Preparation offering immunity against an infectious disease.

• Wet market: Market selling live animals and fish, linked to zoonotic disease outbreaks.

• Zoonotic disease transmission: Diseases transmitted from animals to humans.

Overview of COVID-19's Discovery and Spread

• SARS-CoV-2 was discovered in December 2019 in Wuhan, China, resulting in a severe health crisis.

• Initial outbreaks included severe pneumonia cases, with significant increases in confirmed cases by early 2020.

Coronaviruses and Public Health Impact

• SARS-CoV-2 is the seventh coronavirus strain affecting humans. COVID-19 has profound societal and economic impacts.

Chapter Focus

• This chapter analyzes crowd-epidemic management, SARS-CoV-2 origins, basic epidemiological modeling, public health strategies, and lessons for future health crisis responses.