Table 3. Clinical characteristics associated with laboratory-confirmed respiratory syncytial virus cases detected through the sentinel influenza surveillance system using bivariate logistic regression, Portugal, 2010–2018 (n = 190 cases) .

Clinical characteristics	Total (n = 190)				Age group (years)a
					0–4 (n = 23)				5–14 (n = 8)				15–64 (n = 107)				≥ 65 (n = 45)
	n	%	Crude OR	95% CI	n	%	Crude OR	95% CI	n	%	Crude OR	95% CI	n	%	Crude OR	95% CI	n	%	Crude OR	95% CI
Sudden onset of symptoms	157	82.6	1.1	0.7–1.5	13	56.5	0.4	0.16–1.00b	8	100.0	1.0	NA	97	90.7	2.1	1.1–4.0b	34	75.6	0.8	0.4–1.7
Symptoms
Fever or feverishness	129	67.9	0.4	0.3–0.6b	22	95.7	1.1	0.1–9.3	8	100.0	1.0	NA	70	65.4	0.3	0.2–0.5b	24	53.3	0.6	0.3–1.2
Malaise	164	86.3	0.7	0.44–1.0	17	73.9	1.0	0.4–2.8	7	87.5	1.4	0.2–11.3	97	90.7	0.9	0.4–1.8	39	86.7	0.7	0.3–1.6
Headache	123	64.7	0.7	0.5–0.9b	3	13.0	0.3	0.1–1.0	3	37.5	0.2	0.0–1b	84	78.5	1.1	0.7–1.7	28	62.2	1.0	0.5–1.8
Myalgia	138	72.6	0.4	0.3–0.5b	7	30.4	0.5	0.2–1.2	4	50.0	0.3	0.1–1.3	88	82.2	0.4	0.2–0.6b	36	80.0	0.9	0.4–1.9
Cough	180	94.7	2.4	1.2–6.5b	23	100.0	1.0	NA	7	87.5	0.9	0.1–7.3	99	92.5	1.5	0.7–3.2	44	97.8	1.0	NA
Sore throat	143	75.3	1.2	0.9–1.7	15	65.2	0.6	0.2–1.5	2	25.0	0.1	0.0–0.4b	90	84.1	2.3	1.3–4.2b	32	71.1	1.3	0.6–2.5
Shortness of breath	74	38.9	2.1	1.6–2.9b	12	52.2	6.7	2.6–17.4b	3	37.5	6.7	1.5–28.8b	31	29.0	1.5	1.0–2.3	25	55.6	1.7	0.9–3.2
Case definition
EU ILI	154	81.1	1.2	0.8–1.7	13	56.5	0.5	0.2–1.2	7	87.5	1.7	0.2–13.7	97	90.7	2.5	1.3–4.9b	34	75.6	1.0	0.5–1.9
ARI-like	156	82.1	1.2	0.8–1.8	13	56.5	0.5	0.2–1.1	7	87.5	1.6	0.2–13.5	97	90.7	2.5	1.3–4.8b	34	75.6	0.9	0.5–1.9
One respiratory symptom	189	99.5	6.1	0.9–43.8	23	100.0	1.0	NA	7	87.5	0.2	0.3–2.0	107	100.0	1.0	NA	45	100.0	1	NA

ARI: acute respiratory infection; CI: confidence interval; EU: European Union; ILI: influenza-like illness; NA: not applicable; OR: odds ratio.

^a Age was not known for seven of the 190 patients infected with respiratory syncytial virus.

^b p value < 0.05.