Centers for Disease Control and Prevention, Atlanta, Georgia.
Pan American Health Organization, Washington D.C.
Clin Infect Dis. 2016 May 1;62 Suppl 2:S127-32. doi: 10.1093/cid/civ1017.
Because >60 rotavirus strains have been reported worldwide, concerns exist about strain replacement after the introduction of rotavirus vaccines, particularly in developing countries with diverse strains and lower efficacy.
We used the case-control design in 4 hospitals in Nicaragua to assess strain-specific vaccine effectiveness (VE) of a pentavalent rotavirus vaccine (RotaTeq) against rotavirus diarrhea. Cases were identified through prospective strain surveillance with reverse transcription-polymerase chain reaction for 3 years among children hospitalized for diarrhea, and controls were children negative for rotavirus.
We enrolled 1178 case-patients, 1082 (92%) with G and P typing, and 4927 controls. A different strain predominated each year with increasing age of the vaccine-eligible cohort during the study period: G2P[4] in 2008 (97%; mean age, 11.9 months), G1P[8] in 2009 (55%; mean age, 17.0 months), and G3P[8] in 2010 (78%; mean age, 17.3 months). Overall VE was 45% (95% confidence interval, 25%-59%). Regardless of the strain, VE estimates were 12%-79% lower among children aged ≥12 months relative to those 6-11 months of age. The lower VE for G3P[8] was related to the higher mean age of cases (17.3 months) compared with the G2P[4] strains (11.9 months), with a significant trend (R(2)= 0.819;P< .001) of declining effectiveness with increasing mean age of the cases.
Introduction of RotaTeq did not result in sustained emergence of any particular strain in Nicaragua. Variation in strain-specific effectiveness was due to an age-related decline in effectiveness rather than differences in protection against the observed strains.
由于全世界已报告超过 60 种轮状病毒株，因此人们对轮状病毒疫苗引入后病毒株的替换存在担忧，尤其是在具有多种病毒株且疫苗效力较低的发展中国家。
我们在尼加拉瓜的 4 家医院使用病例对照设计，评估五价轮状病毒疫苗（RotaTeq）针对轮状病毒腹泻的疫苗效力。病例是通过 3 年时间对住院腹泻儿童进行前瞻性病毒株监测，采用逆转录聚合酶链反应检测发现的，对照为轮状病毒阴性的儿童。
我们纳入了 1178 例病例患者，其中 1082 例（92%）进行了 G 和 P 型鉴定，4927 例为对照。在研究期间，随着疫苗适用人群年龄的增长，每年流行的病毒株不同：2008 年为 G2P[4]（97%；平均年龄为 11.9 个月），2009 年为 G1P[8]（55%；平均年龄为 17.0 个月），2010 年为 G3P[8]（78%；平均年龄为 17.3 个月）。总体疫苗效力为 45%（95%置信区间，25%-59%）。无论病毒株如何，≥12 月龄儿童的疫苗效力估计值均比 6-11 月龄儿童低 12%-79%。G3P[8]的较低疫苗效力与病例的平均年龄较高有关（17.3 个月），而 G2P[4]病毒株的平均年龄较低（11.9 个月），且随着病例平均年龄的增加，疫苗效力呈显著下降趋势（R(2)=0.819；P<0.001）。
在尼加拉瓜，RotaTeq 的引入并未导致任何特定病毒株的持续出现。病毒株特异性效力的变化是由于疫苗效力随年龄增长而下降，而不是对观察到的病毒株的保护作用不同所致。
