TABLE 2.

Differences between females and males in frequency of vaccine-related side effects^a

Dose and symptom	Sex	Symptom frequency (no.)b		ORc	P value
		+	−
1st vaccine dose
General fatigue	Female	75	133	2.2	0.03
	Male	11	43
Headache	Female	55	153	6.1	<0.001
	Male	3	51
2nd vaccine dose
General fatigue	Female	150	53	3.5	<0.001
	Male	24	30
Headache	Female	131	72	5.7	<0.001
	Male	13	41
Chills	Female	81	122	2.3	0.02
	Male	12	42
Fever (≥37.5°C)	Female	69	134	4.1	<0.001
	Male	6	48

^aSignificant differences (P < 0.05 by Fisher’s exact test) in frequency of vaccine-related side effects are shown. Results for all side effects are shown in Table S1 in the supplemental material.

^b+, Presence of a symptom; −, absence of a symptom.

^cOR, odds ratio.