Department of Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ottawa, Canada.
PLoS One. 2011;6(12):e27897. doi: 10.1371/journal.pone.0027897. Epub 2011 Dec 12.
Live vaccines have distinct safety profiles, potentially causing systemic reactions one to 2 weeks after administration. In the province of Ontario, Canada, live MMR vaccine is currently recommended at age 12 months and 18 months.
Using the self-controlled case series design we examined 271,495 12 month vaccinations and 184,312 18 month vaccinations to examine the relative incidence of the composite endpoint of emergency room visits or hospital admissions in consecutive one day intervals following vaccination. These were compared to a control period 20 to 28 days later. In a post-hoc analysis we examined the reasons for emergency room visits and the average acuity score at presentation for children during the at-risk period following the 12 month vaccine.
Four to 12 days post 12 month vaccination, children had a 1.33 (1.29-1.38) increased relative incidence of the combined endpoint compared to the control period, or at least one event during the risk interval for every 168 children vaccinated. Ten to 12 days post 18 month vaccination, the relative incidence was 1.25 (95%, 1.17-1.33) which represented at least one excess event for every 730 children vaccinated. The primary reason for increased events was statistically significant elevations in emergency room visits following all vaccinations. There were non-significant increases in hospital admissions. There were an additional 20 febrile seizures for every 100,000 vaccinated at 12 months.
There are significantly elevated risks of primarily emergency room visits approximately one to two weeks following 12 and 18 month vaccination. Future studies should examine whether these events could be predicted or prevented.
活疫苗具有独特的安全性特征，接种后 1 至 2 周内可能会引起全身反应。在加拿大安大略省，活麻疹、腮腺炎、风疹联合疫苗目前建议在 12 个月和 18 个月时接种。
我们使用自我对照病例系列设计，研究了 271495 次 12 月龄接种和 184312 次 18 月龄接种，以检查接种后连续一天间隔内急诊就诊或住院的复合终点的相对发病率。这些与 20 至 28 天后的对照期进行了比较。在事后分析中，我们检查了急诊就诊的原因以及在 12 个月疫苗接种后风险期内就诊儿童的平均严重程度评分。
在接种 12 个月疫苗后 4 至 12 天，与对照期相比，儿童发生复合终点的相对发病率增加了 1.33（1.29-1.38），即每接种 168 名儿童就有 1 例以上事件发生在风险期内。在接种 18 个月疫苗后 10 至 12 天，相对发病率为 1.25（95%，1.17-1.33），这意味着每接种 730 名儿童就会有 1 例以上的额外事件。事件增加的主要原因是所有疫苗接种后急诊就诊的显著升高。住院人数略有增加。在 12 个月时，每接种 10 万人就会增加 20 例热性惊厥。
在接种 12 个月和 18 个月疫苗后大约 1 至 2 周，急诊就诊的风险显著增加。未来的研究应检查这些事件是否可以预测或预防。
