Table 1

Table 1
Annual notified incidence of tick-borne encephalitis and seroprevalence of tick-borne encephalitis virus in blood donors^a, per region, Sweden, 2004–2019 (n = 2,700)
Region	TBE incidence^b		Sera	TBEV seroprevalence
	TBE incidence^b			Vaccinated^d			Infected^e			Total
	Rate	Level^c		n	%	95% CI	n	%	95% CI	n	%	95% CI
Gotland	2.4	Low–medium	300	39	13.0	9.5–17.5	3	1.0	0.2–3.0	42	14.0	10.3–18.4
Gävleborg	0.7	Absent–low	300	54	18.0	13.9–22.9	3	1.0	0.2–3.0	57	19.0	14.7–23.9
Kronoberg	0.7	Absent–low	300	26	8.7	5.8–12.6	3	1.0	0.2–3.0	29	9.7	6.6–13.6
Skåne	0.6	Absent-low	300	53	17.7	13.6–22.6	4	1.3	0.4–3.6	57	19.0	14.7–23.9
Stockholm	4.8	High	300	171	57.0	51.2–62.6	21	7.0	4.5–10.7	192	64.0	58.3–69.4
Uppsala	9.1	High	300	84	28.0	23.1–33.5	9	3.0	1.2–5.4	93	31.0	25.8–36.6
Värmland	1.5	Low–medium	300	97	32.3	27.1–38.0	9	3.0	1.5–5.8	106	35.3	29.9–41.0
Västerbotten	0.1	Absent–low	300	34	11.3	8.1–15.6	3	1.0	0.2–3.0	37	12.3	8.8–16.6
Västra Götaland	1.6	Low–medium	300	120	40.0	34.5–45.8	9	3.0	1.5–5.8	129	43.0	37.3–48.8
Total			2,700	678	25.1	23.5–26.8	64	2.4	1.8–3.0	742	27.5	25.8–29.2
CI: confidence interval; NS1: non-structural protein 1; TBE: tick-borne encephalitis; TBEV: tick-borne encephalitis virus; WV: whole virus. ^a Serum samples from blood donors in Gotland, Gävleborg, Skåne, Uppsala, Värmland, Västerbotten and Västra Götaland were taken 2018 and those from Kronoberg in 2019. ^b Annual notifications per 100,000 inhabitants 2004–2018. Data source: Public Health Agency of Sweden (https://www.folkhalsomyndigheten.se/the-public-health-agency-of-sweden/). ^c Absent–low: 0–1 case/100,000 inhabitants; low–medium: 1–4 cases/100,000 inhabitants; high: > 4 cases/100,000 inhabitants. ^d Individuals were defined as vaccinated if antibodies were detected against TBEV WV but not against NS1. ^e Individuals were defined as infected if antibodies were detected against TBEV WV and NS1.