TABLE 1.

Characteristics of pregnant women at enrolment in the INFLUMIKA ^a cohort

	El Salvador	Panama	P value	Total
n	1051	1505		2556
Age, median (interquartile)	23 (19–27)	24 (20–27)	0.012
Race
Indigenous	1 (0.1%)	400 (26.6%)	<0.001	401 (15.7%)
Mestizo	1049 (99.8%)	758 (50.4%)		1807 (70.7%)
White	0 (0%)	247 (16.4%)		247 (9.7%)
Black	1 (0.1%)	97 (6.4%)		98 (3.8%)
Other	0 (0%)	3 (0.2%)		3 (0.1%)
Primary school or less	265 (28.3%)	212 (17.7%)	<0.001	477 (22.3%)
Income <$400 USD	741 (88.8%)	335 (37.8%)	<0.001	1076 (62.6%)
Drinks alcohol	5 (0.5%)	46 (3.1%)	<0.001	51 (2.0%)
Smoker	6 (0.6%)	12 (0.8%)	0.633	18 (0.7%)
Pre‐existing condition	42 (4%)	171 (11.6%)	<0.001	213 (8.4%)
Asthma	19 (1.8%)	59 (3.9%)	0.002	78 (3.0%)
Hypertension	6 (0.6%)	27 (1.8%)	0.007	33 (1.3%)
Kidney disease	0 (0%)	5 (0.3%)	0.082	5 (0.2%)
Heart disease	1 (0.1%)	3 (2.0%)	0.648	4 (0.2%)
Diabetes	3 (0.3)	2 (0.1%)	0.407	5 (0.2%)
Cancer	0 (0%)	2 (0.1%)	0.516	2 (0.1%)
HIV	0 (0%)	2 (0.1%)	0.516	2 (0.1%)
Primigravid	487 (46.5%)	423 (28.2%)	<0.001	910 (35.7%)
Influenza vaccines
Ever vaccinated	693 (65.9%)	1232 (81.9%)	<0.001	1925 (75.3%)
During pregnancy	625 (59.5%)	1074 (71.4%)	<0.001	1699 (66.5%)
Before influenza epidemics b	133 (12.6%)	652 (43.3%)	<0.001	785 (30.7%)

^a INFLUMIKA is the Spanish language acronym of the cohort (i.e., Influenza maternal e Infantil y Zika).

^b Typical influenza epidemic period April‐September. ¹⁵