Novel respiratory viruses emerged in the past two decades
| Infectious agent | Year of emergence | Location of emergence |
| Influenza H5N1 (avian) | 1997 | Hong Kong |
| SARS coronavirus | 2002 | China |
| Human coronavirus NL63 | 2004 | The Netherlands |
| Bocavirus | 2005 | Sweden |
| Pandemic H1N1 2009 | 2009 | USA/Mexico |
| MERS coronavirus | 2012 | Saudi Arabia |
| Influenza H7N9 (avian) | 2013 | China |
| Influenza H5N6 (avian) | 2014 | China |
| SARS-CoV-2 | 2019 | China |
MERS, Middle East respiratory syndrome; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.