Table 2.

 Frequency of infection by the various human coronaviruses

Country	HCoV‐NL63	HCoV‐229E	HCoV‐OC43	Patient group	Method	Reference
Netherlands (n=63) *	4.7 †	0	4.7	C A H O	RT‐PCR	Private communication ‡
Belgium (n=309)	2.3	0.3	2.3	C H	RT‐PCR (pancorona RT‐PCR)	Moes et al. (2005)
Hong Kong (n=587)	2.6	0.3	1.5	C H	RT‐PCR (real time RT‐PCR)	Chiu et al. (2005)
France (n=300)	9.3	0	2.2	C H	RT‐PCR (multiplex RT‐PCR)	Vabret et al. (2005)
Switzerland (n=82)	7.3	3.7	6.1	C H O	RT‐PCR	Kaiser et al. (2005)

^* Number of samples tested.

^† Percentage of the tested samples positive for the indicated virus.

^‡ S. Bruisten, M. van Zon, J. Spaargaren and L. van der Hoek (data not published).

C, children; A, adults; H, hospitalized patients; O, outpatients; HCoV, human coronavirus.