Table 1. Incidence of influenza and RSV infection by age in pre- and post-intervention and estimates of the causal effect parameter (β) of the national health insurance policy change in RSV antigen detection test funding by age in Japan.

Age (years)	Mean incidence of RSV			Mean incidence of influenza		Unadjusted estimates [95% CI]	Adjusted estimates [95% CI]
	2008/09–2011/12	2012/13–2016/17		2008/09–2011/12	2012/13–2016/17
0–4	1,121	1,953		5,835	5,412	–2,269 [–4,622, 83]	1,255 [–219, 2,749]
5–9	24	36		10,048	8,147	–6,197 [–8,549, –3,844]	1,912 [418, 3,406]
10–14	2	3		5,452	4,457	–3,390 [–5,742, –1,037]	995 [–499, 2,489]
15–19	0.32	0.37		1,382	1,101	–849 [–3,201, 1,504]	281 [–1,214, 1,755]
≥20	0.11	0.13		281	393	–237 [–2,590, 2,115]	–112 [–1,606, 1,382]
Overall	61	99		1,408	1,284	–847 [–934, –759]	162 [85, 240]

Mean incidence (i.e., reported cases) per 100,000 individuals for both infections in pre- and post- intervention are shown. The unadjusted and adjusted estimates (β) should be interpreted as the increase in yearly incidence of RSV infection per 100,000 individuals due to the change in the national insurance policy. Estimates were adjusted with time-dependent effect (δ) and group-dependent effect (γ). 95% CIs of each estimates were calculated through profile likelihood. All estimates were derived from an age-dependent model, except for the last row, which presents estimated parameters from prefecture-dependent model, interpreted as the effect of the total population. RSV, respiratory syncytial virus; CI, confidence interval.