Table 1

Epidemiological and other characteristics of events

EventPHEIC Declaration3 4Date of initial event detectionWHO notified of eventDate of first EC3 4No countries affected prior to first ECNo countries affected at declaration or, if not declared, no countries affected by last ECNo countries affected over course of eventRegions affected over course of eventCase fatality ratio
H1N1 (2009)Declared PHEIC18 March 2009: initial cases of influenza-like illness detected2724 April 2009: WHO releases first disease outbreak News on H1N1 and influenza-like illness in USA and Mexico2725 April 20092323>21427
Worldwide27Of symptomatic cases: 0.0275% (range: 0%
MERS-CoV (2013)PHEIC not declared13 June 2012: first novel coronavirus case admitted to hospital2922 September 2012 WHO first notified of novel coronavirus119 July 20139112611 122711 30Middle East, Africa, Southeast Asia, Europe, North America1136% (range: 20%–43%)31–34
Polio (2014)Declared PHEIC1 January 2014: trend of rising poliovirus international spread noted31 January 2014: trend of rising poliovirus international spread noted328–29 April 20141031031735 36Africa, Middle East, Pacific35 36Estimated 0.025%–0.05%37
EVD (2014)Declared PHEIC26 December 2013: first case develops symptoms3823 March 2014: Guinea MoH notifies WHO of EVD outbreak with 49 cases and 29 deaths146–7 August 20144144141026Africa, North America, Europe3962.9%40
Zika (2016)Declared PHEIC1 July–28 November 2015: detection of relationship between Zika and neurological disorders151 December 2015: WHO & PAHO publish joint findings on Zika and neurological disorder relationship151 February 20162516 172516 178717 41Africa, North America, South America, Central America, Southeast Asia, Western Pacific17 41For fetuses born to Zika-infected mothers: 8.3%
–10.5%42 43
Yellow Fever (2016)PHEIC not declared5 December 2015: first cases identified1821 January 2016: Angola notifies WHO of Yellow Fever outbreak1819 May 20164343444Southeast Asia, Africa3 448.8%45
 EVD (2018)PHEIC not declared3 May 2018: Provincial Health Division reports febrile, haemorrhagic cases and deaths198 May 2018: DRC MoH notifies WHO1918 May 2018146146146Africa4661%47
 EVD (2018)Declared PHEIC28 July 2018: North Kivu Provincial Health Division notified DRC MoH of acute haemorrhagic fever cases31 August 2018: EVD cases confirmed, DRC MoH declares outbreak317 October 2018132323Africa367%14
COVID-19 (2020)Declared PHEIC24 December 2019: Wuhan city health commission notes cases of viral pneumonia4831 December 2019: WHO China Country Office notified of cases of pneumonia of unknown aetiology4122–23 January 20204318321349
All regions affected21Too early to report
  • Polio spread over course of event is non-cumulative. Information is current as of 9 March 2020.

  • *Includes countries, territories and areas.

  • EC, Emergency Committee; EVD, Ebola virus disease; H1N1, influenza A; MERS-CoV, Middle East respiratory syndrome coronavirus; MoH, Ministry of Health; PAHO, Pan American Health Organization; PHEIC, Public Health Emergency of International Concern.