Outdoor recreation, tick borne encephalitis incidence and seasonality in Finland, Norway and Sweden during the COVID-19 pandemic (2020/2021)

Figures & data

Table 1. Annual reported TBE (a) cases and (b) incidences from Finland, Norway and Sweden, summarized for pre-pandemic and covid-19 years.

	Pre-pandemic years 2010–2019						COVID-19 years			After COVID
	Mean	Min	25%	50%	75%	Max	Mean	2020	2021	2022
a) Annual number of cases
Finland	56.7	38	40	54	68.8	85	121	91	151	123
Norway	15.1	6	9.5	12.5	15.5	37	56.5	41	72	69
Sweden	277.1	175	216.2	275.5	339.5	391	404.5	276	533	467
b) Annual incidence
Finland	1.0	0.7	0.7	1.0	1.2	1.5	2.2	1.6	2.7	2.2
Norway	0.3	0.1	0.2	0.2	0.3	0.7	1.0	0.8	1.3	1.3
Sweden	2.8	1.8	2.2	2.9	3.3	3.9	3.9	2.7	5.1	4.4

Figure 1. TBE (A) Annual reported cases and (B) Annual incidence per 100 000 inhabitants estimated as a function of year (linear at log-scale) for each country separately. The lines show mean estimates together with the 95% confidence envelops. Predictions for 2020–2022 (dashed lines) are based on the model fitted to the period 2010–2019. For each country, the average level of the pandemic years (2020–2021) are highlighted by error bars representing the estimate with 95% confidence intervals. Points show the raw data of reported cases per year (A) and annual incidence per 100 000 inhabitants (B).

Figure 2. Weekly number of TBE cases fitted to a seasonal model for A) Finland, B) Norway and C) Sweden. The full model includes estimated values from both the seasonal part (common across years) and the long-term yearly trend of the model. Grey lines show the raw number of weekly cases. D) the seasonal part of the model extracted from each country.

Data availability statement

Available on the public health institutes webpages