Pandemics and Health Care: What are Pandemics?

PANDEMIC: "prevalent throughout an entire country, continent, or the whole world; epidemic over a large area" (Dictionary.com).

•  November 2002  - The Severe Acute Respiratory Syndrome (SARS) first appeared in Southern China. The illness spread to more than two dozen countries in North America, South America, Europe, and Asia before the SARS global outbreak of 2003 was contained. Of the 8,098 people who contracted the illness, 774 died (CDC, "SARS").
•  April 2009  - the H1N1 Influenza Virus, also referred to as the "swine flu", was first detected in people in the United States (CDC, "H1N1 Flu," 2009). The swine flu was discovered in 2016 to have originated "in pigs from a very small region in central Mexico." Ultimately, the virus was responsible for the deaths of over 17,000 people worldwide. (Science Daily, "2009 Swine Flu Pandemic," June 2016).
•  September 2012  - the Middle Eastern respiratory syndrome coronavirus (MERS) was first identified in Saudi Arabia (WHO, "Middle Eastern respiratory syndrome coronavirus (MERS-CoV)"). The largest known outbreak of MERS outside the Arabian Peninsula occurred in the Republic of Korea in 2015. The illness likely came from an animal source in the Arabian Peninsula. Researchers have found MERS-CoV in camels from several countries, and studies have shown that direct contact with camels is a risk factor for human infection with MERS-CoV. There is currently no vaccine for MERS. (CDC, "Middle Eastern respiratory syndrome (MERS)"). Since September 2012, there have been 858 deaths reported from the virus, and at least 2,494 laboratory-reported cases. (WHO).
•  March 2013  - human infections with Avian lineage avian influenza, or the "bird flu" (A(H7N9)) virus were reported for the first time in China. Since then, the virus has spread in the poultry population across the country and resulted in over 1500 reported human cases and many human deaths (WHO, "Influenza (Avian and other zoonotic)"). As of 2018, China was experiencing its 6th epidemic of A(H7N9) human infections, but only 3 cases of human infection had been reported (CDC, "Asian Lineage Avian Influenza A(H7N9) Virus").
•  December 2013  - the Ebola Virus Disease (EVD) was contracted by its initial case, an 18-month-old child, in a small village in Guinea. It is believed the child was infected by a bat. Engaging local leaders in prevention programs and messaging, along with careful policy implementation at the national and global level, helped to eventually contain the spread of the virus and put an end to this outbreak. Two and a half years after the first case was discovered, the outbreak ended with more than 28,600 cases and 11,325 deaths (CDC, "2014-2016 Ebola Outbreak in West Africa").
•  2015 to 2016  - Large outbreaks of the Zika virus, a flavvirus transmitted mainly by mosquitos which was first discovered in 1947 in Uganda, started occurring across North and South America. Zika infection during pregnancy can cause serious birth defects and is associated with other pregnancy problems. In February 2016, WHO declared Zika infection to be a Public Health Emergency of International Concern (PHEIC). (WHO, Zika: the origin and spread of a mosquito-borne virus"). By 2017, cases in the United States started to decline. As of 2019, there have been no confirmed Zika virus disease cases reported from United States territories (CDC, "Zika Virus - Statistics and Maps").
•  December 2019  - The first instance of the coronavirus COVID-19 is identified in Wuhan, China. As of July 2020, there are almost 13 million confirmed cases worldwide, with over 570,000 confirmed deaths, in 216 countries (WHO, "Coronavirus disease (COVID-19) pandemic").

(from Technology Networks, Immunology and Microbiology, "Epidemic vs Pandemic," 2019).

The Center for Disease Control (CDC) broke down the principles of epidemiology ("the branch of medicine which deals with the incidence, distribution, and possible control of diseases and other factors relating to health" - per Oxford Languages Lexico) into the various stages of disease outbreak:

  Endemic:  The amount of a particular disease that is usually present in a community is referred to as the baseline or endemic level of the disease.

While some diseases are so rare in a given population that a single case warrants an epidemiologic investigation (e.g., rabies, plague, polio), other diseases occur more commonly so that only deviations from the norm warrant investigation.

  Sporadic:  a disease that occurs infrequently and irregularly.

 Hyperendemic:  persistent, high levels of disease occurrence.

  Epidemic:   an increase, often sudden, in the number of cases of a disease above what is normally expected in that population in that area.

An epidemic may result from:

• A recent increase in amount or virulence of the agent,
• The recent introduction of the agent into a setting where it has not been before,
• An enhanced mode of transmission so that more susceptible persons are exposed,
• A change in the susceptibility of the host response to the agent, and/or
• Factors that increase host exposure or involve introduction through new portals of entry.

  Pandemic:  an epidemic that has spread over several countries or continents, usually affecting a large number of people.