Ackermann-Gäumann et al..
Prevalence of anti-tick-borne encephalitis virus (TBEV) antibodies in Swiss blood donors in 2014-2015
Blood Transfus. 2022; in press,

In Switzerland, TBE related seroepidemiological studies in blood donors have been carried out in the 1960s and 1970s, and about 0.2% to 0.3% seroprevalence was found in healthy blood donors. New studies have been carried out in 2014/15 to assess the rate of TBE antibody positivity among Swiss blood donors and to study differences according to age, gender and endemicity (endemic, nonendemic, border regions).

In total, 9,328 blood donors voluntarily participated in the study (39% females, 61% males). 26.4% of the participants indicated TBE vaccination. 19.0% of samples from blood donors reporting previous TBE vaccination(s) were tested TBE antibody negative by using ELISA tests (number of vaccinations and latest injection unknown). TBE antibodies were detected in 84.3% of female and 79.3% of male blood donors. Vaccination was more frequently indicated by blood donors in endemic than in border or non-endemic regions. TBE antibodies in blood donors indicating no TBE or other flavivirus vaccination, were detected in 5.6%, and the antibody prevalence was higher in individuals from endemic than from border or non-endemic regions and was higher in non-vaccinated males than in females. In the canton of Ticino (southern Switzerland), where TBE vaccination was yet not recommended, antibody prevalence was 3.8% among blood donors.

A possible asymptomatic TBE virus infection was found in 5.6% of blood donors in 2014/15, which was much higher than found in the 1960s and 1970s. Although the prevalence was higher in endemic than in non-endemic regions, the authors concluded that the whole population of Switzerland should be regarded at risk of TBE virus infections.

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