Table 2.

Characteristics of study population.

Authors, Year	Cases (n = 6200)	Controls (n = 4986)	Cases Median (IQR) age(Month)	Control Median (IQR) age(Month)
Kelly et al., 2015 [18]	310	133	7.0 (3.0–13.3)	6.4 (4.0–12.2)
Bigogo et al., 2013 [19]	538	193	Not mentioned	Not mentioned
Fuller et al., 2013 [20]	680	136	Not mentioned	Not mentioned
Bénet et al., 2015 [21]	118	98	12 (5–26)	11 (5–23)
Zar et al., 2016 [22]	284	412	5 (3–9)	5 (2–8)
Hammitt et al., 2012 [23]	105	190	9.7 (3.8–18.7), 13 (average)	20 (average)
Mwananyanda et al., 2021 [24]	473	530	4.0 (3.0, 5.0)	4.0 (2.0, 4.0)
Tapia et al., 2021 [25]	650	724	6 (3–13)	9 (4–20)
Awori et al., 2021 [26]	628	855	Not mentioned	Not mentioned
Howie et al., 2021 [27]	609	624	8 (3–18)	11 (5–22)
Moore et al., 2021 [28]	795	823	5.0 (2.0–12.0)	8.0 (4.0–16.0)
Bénet et al., 2017 [29]	80	60	mean (SD),22.2 (14.6)	mean (SD),17.1 (12.6)
Feikin et al., 2013 [8]	199	93	18	15
Breiman et al., 2015 [30]	731	115	18	21.6