Coverage and Effectiveness of Kyasanur Forest Disease (KFD) Vaccine in Karnataka, South India, 2005-10
Coverage and Effectiveness of Kyasanur Forest Disease (KFD) Vaccine in Karnataka, South India, 2005-10
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DOI：
10.1371/journal.pntd.0002025
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发表时间：
2013-01-01
影响因子：
3.8
通讯作者：
Mehendale, Sanjay M.
中科院分区：
文献类型：
--
作者：
Kasabi, Gudadappa S.;Murhekar, Manoj V.;Mehendale, Sanjay M.
背景资料：Kyasanur森林病（KFD）是一种具有出血表现的蜱传病毒性疾病，局限于印度卡纳塔克邦的五个地区。自1990年以来，该地区每年都使用福尔马林灭活组织培养疫苗进行接种。对7-65岁的人每隔一个月接种两剂疫苗，然后在6-9个月后定期加强接种。尽管在早期研究中报告了疫苗的高有效性，但最近报告了接种疫苗的个体中的KFD病例。我们分析了2005年至2010年KFD疫苗接种和病例监测数据。方法/主要结果：我们计算了接种和未接种人群中KFD的发病率，并计算了相对风险和疫苗有效性。在2005-2010年期间，共有343，256人有资格接种克流感疫苗（2008年的疫苗接种详情不详）。其中，52%的人没有接种任何疫苗，36%的人接种了两剂疫苗和一剂加强疫苗。在这5年期间报告的168例实验室确诊的KFD病例中，134例（80%）未接种疫苗，9例分别接种了1剂和2剂，16例在传播前季节接受了加强剂。接种1针、2针和加强针后发病的相对危险度分别为1.06（95% CI = 0.542.1）、0.38（95% CI = 0.19-0.74）和0.17（95% CI = 0.10-0.29）。接种两剂疫苗的有效率为62.4%（95%CI = 26.1-80.8），接种两剂疫苗后再加强一剂的有效率为82.9%（95%CI = 71.3-89.8）。与早期报告相比，观察到的KFD疫苗的有效性较低，尤其是单次给药后。需要作出系统的努力，提高疫苗覆盖率，并查明该区域疫苗效力较低的原因。
Background: Kyasanur forest disease (KFD), a tick-borne viral disease with hemorrhagic manifestations, is localised in five districts of Karnataka state, India. Annual rounds of vaccination using formalin inactivated tissue-culture vaccine have been conducted in the region since 1990. Two doses of vaccine are administered to individuals aged 7-65 years at an interval of one month followed by periodic boosters after 6-9 months. In spite of high effectiveness of the vaccine reported in earlier studies, KFD cases among vaccinated individuals have been recently reported. We analysed KFD vaccination and case surveillance data from 2005 to 2010.Methodology/Principal Findings: We calculated KFD incidence among vaccinated and unvaccinated populations and computed the relative risk and vaccine effectiveness. During 2005-2010, a total of 343,256 individuals were eligible for KFD vaccination (details of vaccination for 2008 were not available). Of these, 52% did not receive any vaccine while 36% had received two doses and a booster. Of the 168 laboratory-confirmed KFD cases reported during this 5-year period, 134 (80%) were unvaccinated, nine each had received one and two doses respectively while 16 had received a booster during the pre-transmission season. The relative risks of disease following one, two and booster doses of vaccine were 1.06 (95% CI = 0.542.1), 0.38 (95% CI = 0.19-0.74) and 0.17 (95% CI = 0.10-0.29) respectively. The effectiveness of the vaccine was 62.4% (95% CI = 26.1-80.8) among those who received two doses and 82.9% (95% CI = 71.3-89.8) for those who received two doses followed by a booster dose as compared to the unvaccinated individuals.Conclusions: Coverage of KFD vaccine in the study area was low. Observed effectiveness of the KFD vaccine was lower as compared to the earlier reports, especially after a single dose administration. Systematic efforts are needed to increase the vaccine coverage and identify the reasons for lower effectiveness of the vaccine in the region.