Table 3.

Concurrently isolated viruses in each child, by sampling period

Number of isolated viruses in each child	1st period		2nd period		3rd period		4th period		p
	2	3	2	3	2	3	2	3
Samples from urban areas	12	1	12	2	4	1	8	1	0.46
Samples from rural areas	4	1	14	6	5	0	6	3

The first line of the table denotes the number of different viruses isolated concurrently in the same child. The p value, which represents the comparison of distributions in the number of isolated viruses in each child per sampling period, between urban and rural areas, was calculated with Poisson regression.