Table 3

Examples of emerging human respiratory viral diseases without sustained human-to-human transmission

VirusOriginating animal hostCharacteristicsNo. of cases; CFR
  • First emerged in China in November 2002.76

  • Causes severe acute respiratory syndrome (SARS).

  • Transmission through superspreading events in healthcare facilities.77

8422 cases; CFR:10%78
  • First emerged in the Middle East in 2012.79

  • Causes Middle East respiratory syndrome (MERS).

  • Outbreaks from 2012 to 2019 in Saudi Arabia and one outbreak in South Korea (2015).

2502 cases; CFR: 34%79
Avian influenza A (H5N1 and H7N9)Birds/poultry
  • Subtypes of influenza viruses detected in birds (having killed millions of poultry) but with ‘pandemic potential’ (WHO).80

  • H5N1 first detected in humans in 1997 in China with widespread emergence in 2003–2004; no sustained community-level transmission.80

  • H7N9 first detected in humans in China in 2013.81

 H5N1: 649 cases; CFR: 60%82
 H7N9: 571 cases; CFR: 37%81
Ebola virusBat
  • First appeared in 1976 and caused over 20 documented ‘major’ outbreaks.83

  • Largest epidemics in 2014–2016 in Guinea, Liberia and Sierra Leone.

  • Ongoing epidemic in the Democratic Republic of Congo.

Over 30 000 cases; average CFR: 50%83
  • CFR, case fatality rates.