Abstract：
OBJECTIVE: Tick-borne encephalitis (TBE) is an infection by the tick-borne encephalitis virus (TBEV) that results in symptoms of central nervous system inflammation. TBE is endemic in Latvia and other European countries. TBE vaccines are commonly used in Latvia, but vaccine effectiveness estimates are limited.
METHODS: Study staff at Rīga Stradinš University conducted nationwide active surveillance for TBEV infections. Serum and cerebrospinal fluid were ELISA-tested for TBEV-specific IgG and IgM antibodies. Vaccination history was collected by interview and medical record review. Utilizing data from surveillance and population surveys, vaccine effectiveness (with 95% CIs) and cases averted were estimated using the screening method.
RESULTS: There were 587 laboratory-identified TBE cases from 2018 to 2020; 98.1% (576/587) were unvaccinated, 1.5% (9/587) were unknown or partially vaccinated, and 0.3% (2/587) were fully vaccinated (three-dose primary series and appropriately timed boosters). TBE resulted in the death of 1.7% (10/587) of TBE cases. TBE vaccine history was ascertained from 92.0% (13 247/14 399) people from the general population: 38.6% (5113/13 247) were unvaccinated, 26.3% (3484/13 247) were fully vaccinated, and 35.1% (4650/13 247) were partially vaccinated. TBE vaccine effectiveness was 99.5% (98.0-99.9) against TBE, 99.5% (97.9-99.9) against TBE hospitalization, 99.3% (94.8-99.9) against moderate/severe TBE, and 99.2% (94.4-99.9) against TBE hospitalization >12 days. From 2018 to 2020, vaccination averted 906 TBE cases, including 20 deaths.
CONCLUSIONS: TBE vaccine was highly effective in preventing TBE, moderate and severe disease, and prolonged hospitalization. To prevent life-threatening TBE, TBE vaccine uptake and compliance should be increased in Latvia and other European regions where TBE is endemic.
METHODS: Study staff at Rīga Stradinš University conducted nationwide active surveillance for TBEV infections. Serum and cerebrospinal fluid were ELISA-tested for TBEV-specific IgG and IgM antibodies. Vaccination history was collected by interview and medical record review. Utilizing data from surveillance and population surveys, vaccine effectiveness (with 95% CIs) and cases averted were estimated using the screening method.
RESULTS: There were 587 laboratory-identified TBE cases from 2018 to 2020; 98.1% (576/587) were unvaccinated, 1.5% (9/587) were unknown or partially vaccinated, and 0.3% (2/587) were fully vaccinated (three-dose primary series and appropriately timed boosters). TBE resulted in the death of 1.7% (10/587) of TBE cases. TBE vaccine history was ascertained from 92.0% (13 247/14 399) people from the general population: 38.6% (5113/13 247) were unvaccinated, 26.3% (3484/13 247) were fully vaccinated, and 35.1% (4650/13 247) were partially vaccinated. TBE vaccine effectiveness was 99.5% (98.0-99.9) against TBE, 99.5% (97.9-99.9) against TBE hospitalization, 99.3% (94.8-99.9) against moderate/severe TBE, and 99.2% (94.4-99.9) against TBE hospitalization >12 days. From 2018 to 2020, vaccination averted 906 TBE cases, including 20 deaths.
CONCLUSIONS: TBE vaccine was highly effective in preventing TBE, moderate and severe disease, and prolonged hospitalization. To prevent life-threatening TBE, TBE vaccine uptake and compliance should be increased in Latvia and other European regions where TBE is endemic.
摘要：
目的：蜱传脑炎（TBE）是由蜱传脑炎病毒（TBEV）引起的感染，导致中枢神经系统炎症的症状。TBE在拉脱维亚和其他欧洲国家流行。TBE疫苗通常在拉脱维亚使用，但是疫苗有效性估计是有限的。
方法：里加·斯特拉丁什大学的研究人员在全国范围内对TBEV感染进行了主动监测。血清和脑脊液进行TBEV特异性IgG和IgM抗体的ELISA检测。通过访谈和病历审查收集疫苗接种史。利用监测和人口调查的数据，使用筛选方法估计疫苗有效性(95%置信区间)和避免的病例.
结果：2018-2020年有587例实验室鉴定的TBE病例；98.1%(576/587)未接种疫苗，1.5%(9/587)未知或部分接种疫苗，和0.3％（2/587）完全接种疫苗（三剂主要系列和适当定时的加强剂）。TBE导致1.7%(10/587)的TBE死亡。从普通人群中92.0%(13,247/14,399)的人群中确定了TBE疫苗史：38.6%(5113/13,247)未接种疫苗，26.3％（3484/13,247）完全接种疫苗，35.1%(4650/13,247)接受了部分疫苗接种。TBE疫苗对TBE的有效性为99.5％（98.0-99.9），99.5％（97.9-99.9）反对TBE住院，99.3%（94.8-99.9）对中度/重度TBE，99.2%(94.4-99.9)的TBE住院时间>12天。从2018年到2020年，疫苗接种避免了906例TBE病例，包括20人死亡。
结论：TBE疫苗在预防TBE方面非常有效，中度和重度疾病，和长期住院。为了防止危及生命的TBE，在TBE流行的拉脱维亚和其他欧洲地区，应增加TBE疫苗的吸收和依从性。
方法：里加·斯特拉丁什大学的研究人员在全国范围内对TBEV感染进行了主动监测。血清和脑脊液进行TBEV特异性IgG和IgM抗体的ELISA检测。通过访谈和病历审查收集疫苗接种史。利用监测和人口调查的数据，使用筛选方法估计疫苗有效性(95%置信区间)和避免的病例.
结果：2018-2020年有587例实验室鉴定的TBE病例；98.1%(576/587)未接种疫苗，1.5%(9/587)未知或部分接种疫苗，和0.3％（2/587）完全接种疫苗（三剂主要系列和适当定时的加强剂）。TBE导致1.7%(10/587)的TBE死亡。从普通人群中92.0%(13,247/14,399)的人群中确定了TBE疫苗史：38.6%(5113/13,247)未接种疫苗，26.3％（3484/13,247）完全接种疫苗，35.1%(4650/13,247)接受了部分疫苗接种。TBE疫苗对TBE的有效性为99.5％（98.0-99.9），99.5％（97.9-99.9）反对TBE住院，99.3%（94.8-99.9）对中度/重度TBE，99.2%(94.4-99.9)的TBE住院时间>12天。从2018年到2020年，疫苗接种避免了906例TBE病例，包括20人死亡。
结论：TBE疫苗在预防TBE方面非常有效，中度和重度疾病，和长期住院。为了防止危及生命的TBE，在TBE流行的拉脱维亚和其他欧洲地区，应增加TBE疫苗的吸收和依从性。
