What is a pandemic?

The World Health Organization (WHO) divides infectious disease warning levels from 1 to 6 according to the risk of infectious diseases, and the pandemic corresponds to the highest warning level of 6 levels. The pandemic is a global epidemic of a specific disease, and in order to meet this, the infectious disease must spread beyond a specific regional outbreak and spread to more than two continents.

Prior to stage 6, stage 1 is an animal-specific infection, stage 2 is a state of infection to a small number of people beyond animal-to-animal transmission, stage 3 is a state of increased infection between people, and stage 4 is a globally-widened infection with rapid spread of infection between people. In the early stage of the outbreak, stage 5, the infection is widespread and the disease is prevalent in at least two countries. In addition, the 6th stage pandemic is a state in which additional infections have occurred in countries on other continents beyond stage 5, and the disease belonging to the pandemic in the history of mankind is the’Black Death’ (Pest), which almost annihilated medieval Europe in the 14th century, and around the world in 1918. The Spanish flu, which killed more than 50 million people in the country, and the Hong Kong flu, killed 1 million in 1968. In particular, since the WHO was founded in 1948, there have been only three cases of pandemic declarations: the Hong Kong flu in 1968, the swine flu in 2009, and the COVID-19 in 2020.

WHO’s Pandemic Declaration Cases

Hong Kong Flu (1968)

It is the first flu that occurred in Hong Kong in 1968. It is an infectious disease accompanied by respiratory symptoms, chills, fever, muscle pain, and lethargy. During the last six months of the flu, more than one million people have died around the world as the flu spread to Australia, Africa, South America and Europe beyond Hong Kong as well as neighboring Asian countries such as Vietnam, India and the Philippines.

Swine flu (2009)

It is an infectious disease that began in Mexico in the spring of 2009 and has since spread beyond the United States around the world. Initially, it was called’swine flu’ because it was caused by pigs infected with the type A influenza virus. At the time, the H1N1 flu outbreak occurred in 214 countries, killing 18,500 people worldwide. However, as the antiviral drug Tamiflu was used as a treatment, it is now called as type A flu, not swine flu.

COVID-19 (2020)

It is a respiratory infection that has spread throughout China and around the world since it first occurred in Wuhan City, Hubei Province, China in December 2019. Initially, it was known only as a respiratory infectious disease of unknown cause, but it was later confirmed to be an infectious disease caused by a new type of coronavirus (SARS-CoV-2, named on February 11 of the International Virus Classification Committee). As the spread of COVID-19 spread around the world, WHO declared an international public health emergency (PHEIC) on January 30, 2020, and declared a pandemic for the third time in history on March 11.

Epidemic and Endemic


Epidemic refers to an infectious disease that spreads over a relatively large area, although it does not span a wide area across continents like the pandemic. Compared to the spread of the pandemic around the world, it refers to a case where it is limited to a specific area, and the infection rate is very fast, less than 2 weeks.

Also, endemic refers to endemic diseases that occur periodically among residents of a specific area, unlike pandemics or epidemics that cause strong damage in a large area. Because endemic is an infectious disease that occurs periodically in a limited area, the number of infected people can be predicted to some extent. For example, malaria and dengue fever, which are common in Southeast Asia, South America, and Africa, belong to this.

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