Table 2.

Influenza B repeat infection odds.

Seasons	N	NRI	aOR*	95% CI	Antigenic distance
B/Victoria
One year apart
Summary		0	0.00	(0.00–0.14)
2016 to 2017	1725	0	0.00	(0.00–0.18)	1.6
2017 to 2018	1727	0	0.00	(0.00–0.21)	1.6
2018 to 2019	1730	0	0.00	(0.00–0.41)	1.6
Two years apart
Summary		0	0.00	(0.00–0.32)
2016 to 2018	1457	0	0.00	(0.00–0.72)	1.6
2017 to 2019	1550	0	0.00	(0.00–0.12)	1.6
Three years apart
2016 to 2019	1295	1	1.68	(0.06–10.05)	1.6
Four years apart
2012 to 2016	1076	0	0.00	(0.00–0.43)	0.8
Five years apart
2012 to 2017	935	3	0.42	(0.09–1.23)	0.8
Six years apart
2012 to 2018	759	1	0.44	(0.01–2.75)	0.8
Seven years apart
2012 to 2019	637	2	0.96	(0.13–3.91)	0.8
B/Yamagata
Two years apart
2017 to 2019	1585	2	0.60	(0.09–2.10)	0.6
Three years apart
2014 to 2017	1326	4	0.74	(0.21–1.92)	0.6
Five years apart
2014 to 2019	1018	1	0.11	(0.00–0.65)	0.6

*All models were adjusted for the age and sex of participants.