Table 2.

Vaccination of soldiers at a US army technical school, 1942–4

		Number of pneumonia cases
Serotypes included in the vaccine		Controls (n = 8449)	Vaccine recipients (n = 8586)
1	yes	2	2
2	yes	14	1*
4	no	6	8
5	yes	4	1
7	yes	6	0*
12	no	25	21
other	no	28	27

From reference [26]

^*p ≤ 0.05