Coronavirus Disease 2019 (COVID-19)

Coronavirus Disease 2019 (COVID-19)


Coronaviruses (CoV) are a large family of viruses that cause illness ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS-CoV). A novel coronavirus (nCoV) is a new strain that has not been previously identified in humans.

COVID-19 is the infectious disease caused by SARS-CoV-2 discovered in Wuhan, China.


In December 2019, the novel coronavirus outbreak began in Wuhan, China. According to the World Health Organization (WHO), the new virus and disease were unknown before the outbreak began in Wuhan.

The outbreak was first reported on 31 Dec. 2019, and came to wide international attention in January 2020. In February 2020, WHO named the disease caused by the virus “coronavirus disease 2019,” which is abbreviated as COVID-19. On 11 March 2020, WHO declared that COVID-19 could be characterized as a pandemic and said it was the first time that a pandemic has been sparked by a coronavirus.

In a statement issued 5 May 2023, the WHO director general, concurring with the advice of the International Health Regulations (2005) (IHR) Emergency Committee, determined that COVID-19 is "now an established and ongoing health issue which no longer constitutes a public health emergency of international concern (PHEIC). During its deliberations, the IHR Emergency Committee highlighted the decreasing trend in COVID-19  deaths, the decline in COVID-19 related hospitalizations and intensive care unit admissions, and the high levels of population immunity to SARS-CoV-2." While acknowledging the uncertainties surrounding the potential evolution of SARS-CoV-2, the committee advised that it is time to transition to long-term management of the COVID-19 pandemic.

As of mid-May 2023, nearly 767 million cases of COVID-19 have been reported around the world and there had been more than 6.9 million confirmed deaths.


People with COVID-19 have reported a variety of symptoms, ranging from mild symptoms to severe illness. Symptoms may appear from one to 14 days after exposure to the virus, but the average is five to six days.

The most common symptoms of COVID-19 are fever, dry cough and fatigue.

Other symptoms that are less common and may affect some patients include:

  • New loss of taste or smell,
  • Nasal congestion,
  • Sore throat,
  • Headache
  • Muscle or joint pain,
  • Different types of skin rash,
  • Nausea or vomiting
  • Diarrhea
  • Chills or dizziness
  • Conjunctivits

Symptoms of severe COVID-19 include shortness of breath, loss of appetite, confusion, persistent pain in the chest, and high temperature (above 38 degrees C).

A list of other, less common symptoms is available on the WHO website.

Older adults and people who have severe underlying medical conditions, like heart disease, lung disease or diabetes, seem to be a higher risk for developing more severe complications from COVID-19 illness, according to the U.S. Centers for Disease Control and Prevention (CDC),


Like other viruses, SARS-CoV-2 is constantly evolving through random mutations. New mutations can increase or decrease infectiousness and virulence. Several variants have been identified and assigned Greek letter designations by the WHO. Variants are designated as variants of concern (VOC) if they display characteristics like increased transmissability or virulence. Since the beginning of the pandemic, multiple VOCs and variants of interest have been designated by WHO.

The Omicron variant, which was first identified in South Africa and is more transmissable than other variants, was designated a VOC in November 2021 and became the dominant variant around the world. Another VOC is the Delta variant, first identified in India, which may cause more severe cases than other variants.


An accelerated international development program resulted in the first vaccine being approved for emergency use in late 2020. In many regions, health care workers, other medical professionals, and elderly/vulnerable populations were prioritized for early vaccinations. At least 15 different vaccines have been administered. As of 23 May 2023, more than 13.3 billion vaccine does had been administered, including booster doses in some regions. 

Vaccines reduce the risk of severe illness, hospitalization and death from COVID-19. The vaccines have been shown to be effective in reducing SARS-CoV-2 transmission and preventing COVID-19. In addition, people who are up to date on vaccines, including booster doses where eligible, are likely to have stronger protection against variants. More information is available on the WHO variant tracking website.

Impact on Aviation

In March 2020, as COVID-19 spread rapidly around the world, air transport activity went into a steep decline. The sharp decline in passenger traffic, caused by fears of COVID-19 exposure and government efforts to slow the spread of the disease that included border restrictions and quarantine requirements, resulted in thousands of commercial aircraft being grounded, with many being put into long-term storage.

The International Air Transport Association (IATA) has called 2020 the worst year in history for air travel demand. For the year, global scheduled passenger traffic, as measured in revenue passenger kilometers, fell by 65.9% and capacity, as measured in available seat kilometers, declined 56.5% from 2019 levels. The total number of domestic and international passenger and cargo flights declined nearly 34% in 2020 from 2019, according to International Civil Aviation Organization (ICAO) statistics. ICAO estimates that 50% fewer scheduled passenger seats were offered in 2020 than in 2019, that there was a 60% reduction in total passengers to 2.7 billion and that airlines lost US$372 billion in gross operating revenues. Air navigation service providers lost US$12.93 billion in navigation charge revenue and airports lost US$114.58 billion, ICAO statistics show.

Air travel recovered somewhat in 2021 as more people were vaccinated and consumer confidence increased. However, variant outbreaks had negative impacts on the recovery. ICAO estimates that scheduled passenger seats offered were down 40% in 2021 compared to 2019 and total passengers carried was down 49%. Recovery to pre-pandemic levels is expected to take several years. ICAO has forecast that the number of passengers carried in 2022 will be 26%-31% lower than in 2019.

In 2022, air travel continued to recover, although not uniformly across the globe. Worldwide the number passengers in 2022 was down 28-29% from 2019 and airline gross passenger operating revenues were down about US$175 billon. Domestic traffic recovered has outpaced international traffic recovery. 

Operational issues faced by the aviation industry during the pandemic ranged from quickly and securely parking thousands of aircraft and subsequently bringing many of those aircraft back into service; to the mental, physical and emotional well-being of personnel, the loss of pilot currency and "rustiness" from long periods of not flying, and navigating a disjointed maze of international travel restrictions. 

A harder to define impact of the pandemic is the loss of tens of thousands of trained and experienced industry personnel through retirements and redundancies. Many in the industry believe that replacing the combined experience and institutional knowledge of those personnel will be difficult and is a risk that needs to be accounted for in safety management systems. 

Guidance Material

ICAO issued multiple electronic bulletins (EB) and State letters providing aviation-related information on COVID-19 and outlining State roles. ICAO urged member States to implement relevant provisions of ICAO Annex 9, Facilitation, which pertains to the facilitation of landside formalities for clearing aircraft, passengers, goods and mail with respect to the requirements of customs, immigration public health and agriculture authorities. ICAO also urged States to become members of the Collaborative Arrangement for the Prevention and Management of Public Health Events in Civil Aviation (CAPSCA); enhance national facilitation (FAL) committees by clarifying roles and responsibilities of public health and civil aviation authorities during outbreaks; implement effective collaboration and coordination strategies with all stakeholders; and provide financial and in-kind assistance to support to the CAPSCA programme.

Much of the ICAO COVID-19 work has been undertaken by the ICAO Council's Aviation Recover Task Force (CART), which is intended to provide practical, aligned guidance to governments and industry operators in order to restart the international air transport sector and recover from the impacts of COVID-19 on a coordinated global basis.

Many regulatory organisations, including the European Union Aviation Safety Agency (EASA), the U.S. Federal Aviation Administration (FAA), published guidance for aviation stakeholders, including operators, airports, air navigation service providers, on how to handle COVID-19. International health organisations, such as the U.S. Centers for Disease Control and Prevention (CDC), have issued guidance and recommendations for travelers.

Trade organisations and industry associations have issued guidance on a range of topics, including business continuity, transporting cargo in passenger cabins, temporary overflow parking of grounded airline fleets, ground handling, facilitating air cargo operations, personal wellbeing, and resuming operations. As the pandemic progressed, the tone of the guidance shifted to preparing for recovery of operations.

The CDC, WHO, IATA, ICAO and the EC all have developed web-based guidance and informational material. The material was updated frequently during the height of the pandemic, but less often as the pandemic evolved. Links can be found below under Web-based Resources.

Related Articles

Web-based Resources

Airports Council International (ACI)


U.S. Centers for Disease Control and Prevention (CDC)

European Centre for Disease Prevention and Control (ECDC)

European Commission/European Union

European Union Aviation Safety Agency (EASA)

Federal Aviation Administration (FAA)

Flight Safety Foundation





World Health Organisation (WHO)


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