Vaccination against Tick-Borne Encephalitis (TBE) in Italy: Still a Long Way to Go

Abstract

Tick-borne encephalitis (TBE) is endemic in several European countries, and its incidence has recently increased. Various factors may explain this phenomenon: social factors (changes in human behavior, duration and type of leisure activities and increased tourism in European high-risk areas), ecological factors (e.g., effects of climate change on the tick population and reservoir animals), and technological factors (improved diagnostics, increased medical awareness). Furthermore, the real burden of TBE is not completely known, as the performance of surveillance systems is suboptimal and cases of disease are under-reported in several areas. Given the potentially severe clinical course of the disease, the absence of any antiviral therapy, and the impossibility of interrupting the transmission of the virus in nature, vaccination is the mainstay of prevention and control. TBE vaccines are effective (protective effect of approximately 95% after completion of the basic vaccination-three doses) and well tolerated. However, their uptake in endemic areas is suboptimal. In the main endemic countries where vaccination is included in the national/regional immunization program (with reimbursed vaccination programs), this decision was driven by a cost-effectiveness assessment (CEA), which is a helpful tool in the decision-making process. All CEA studies conducted have demonstrated the cost-effectiveness of TBE vaccination. Unfortunately, CEA is still lacking in many endemic countries, including Italy. In the future, it will be necessary to fill this gap in order to introduce an effective vaccination strategy in endemic areas. Finally, raising awareness of TBE, its consequences and the benefit of vaccination is critical in order to increase vaccination coverage and reduce the burden of the disease.

Keywords: TBE; TBE vaccine; cost-effectiveness assessment; tick-borne encephalitis; tick-borne encephalitis virus; vaccination; vaccination strategies.

Figure 2

Map of the Italy showing areas where TBE is present. The average annual incidence in the north-eastern area is shown in detail [12,29,30].

Figure 3

Annual number of TBE cases reported in Italy from 2000 to 2020 (Adapted from ref. [27]).

Figure 4

Venn diagram showing the number and percentage of cases of TBE identified by 2 sources: the MNS and HDRs in Veneto from 2007 to 2018. MNS, mandatory notification system; HDRs, hospital discharge records. (Adapted from ref. [12]).

Figure 1

Distribution of confirmed tick-borne encephalitis cases per 100,000 population by country; EU/EEA, 2019 Source: Country reports from Austria, Belgium, Bulgaria, Croatia, Czechia, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, the Netherlands, Norway, Poland, Romania, Slovakia, Slovenia, Spain, Sweden, and the United Kingdom (Adapted from [13]).

Figure 5

Trend of the adjusted rate and number of cases by geographical area (2007–2018) (Adapted from ref. [12]).