Kentucky Pediatric and Adult Research, Bardstown, Kentucky 40004-1142, USA.
Clin Ther. 2009 Oct;31(10):2140-7. doi: 10.1016/j.clinthera.2009.09.014.
Although 2 doses of influenza vaccine are recommended for children aged <9 years who have not been previously vaccinated, children may receive only 1 dose because of suboptimal adherence to national influenza vaccination recommendations.
This study evaluated the efficacy and tolerability of a single dose of the live attenuated influenza vaccine (LAIV) in previously unvaccinated children aged > or = 2 years, the population for which LAIV is approved.
This study was a post hoc subgroup analysis of previously published studies. Three randomized, double-blind, placebo-controlled clinical trials have evaluated the efficacy of a single dose of LAIV in previously unvaccinated young children. Single-dose efficacy, as a prespecified outcome, was evaluated in the subgroup of children aged 2 to 6 years. Reactogenicity and adverse events through 10 days after vaccination were reported after 1 and 2 doses.
Across all studies combined, the mean (SD) ages of the children within the subgroups analyzed were 35.8 (12.1) months for LAIV recipients and 34.5 (11.3) months for placebo recipients. The groups were balanced by sex, with 51% and 50% boys in the LAIV and placebo groups, respectively. The LAIV and placebo groups were also balanced with regard to the countries of origin, as follows: United States (35% LAIV, 31% placebo), Southeast Asia (35% LAIV, 44% placebo), South America (19% LAIV, 15% placebo), and South Africa (11% LAIV, 11% placebo). In a post hoc subgroup analysis of children aged 2 to 6 years from these 3 studies, the efficacy of a single dose of LAIV compared with placebo was 71.5% (95% CI, 52.9% to 83.4%), 87.3% (95% CI, 59.2% to 96.1%), and 59.9% (95% CI, 31.1% to 77.4%). Two of the studies compared the efficacy of 1 and 2 doses of vaccine in the same season. The 1-dose efficacy of LAIV was 87% to 92% of the 2-dose efficacy. Upon revaccination in year 2 with a single dose, year-2 efficacy was not significantly different for children who received either 1 or 2 doses in year 1 (1 dose in year 1, efficacy 64.1% [95% CI, 13.1% to 85.7%]; 2 doses in year 1, efficacy 55.4% [95% CI, -23.6% to 85.9%]; P = NS). All reactogenicity events associated with the first dose of LAIV were decreased after the second dose, with the exception of cough.
A single dose of LAIV provided significant but not optimal protection against influenza in previously unvaccinated children. This finding may be of particular importance for children who are at risk of being partially immunized.
尽管推荐为未接种过流感疫苗的＜9 岁儿童接种 2 剂流感疫苗，但由于国家流感疫苗接种推荐方案的依从性不理想，儿童可能仅接种 1 剂。
本研究评估了活减毒流感疫苗（LAIV）在既往未接种、适用于 LAIV 的＞2 岁儿童中的单剂接种的疗效和耐受性。
本研究是已发表研究的事后亚组分析。3 项随机、双盲、安慰剂对照临床试验评估了既往未接种的幼儿中单剂 LAIV 的疗效。单剂疗效作为预设结局，在 2 至 6 岁儿童亚组中进行评估。接种后 1 和 2 剂时报告了 10 天内的不良反应和不良事件。
在所有研究中，亚组分析中儿童的平均（SD）年龄为 LAIV 组 35.8（12.1）个月，安慰剂组 34.5（11.3）个月。LAIV 组和安慰剂组在性别上均衡，分别有 51%和 50%的男孩。LAIV 组和安慰剂组在疫苗来源国方面也均衡，分别为：美国（LAIV 组 35%，安慰剂组 31%）、东南亚（LAIV 组 35%，安慰剂组 44%）、南美洲（LAIV 组 19%，安慰剂组 15%）和南非（LAIV 组 11%，安慰剂组 11%）。在这 3 项研究的 2 至 6 岁儿童的事后亚组分析中，LAIV 与安慰剂相比的单剂疗效为 71.5%（95%CI，52.9%至 83.4%）、87.3%（95%CI，59.2%至 96.1%）和 59.9%（95%CI，31.1%至 77.4%）。其中 2 项研究比较了同一季节接种 1 剂和 2 剂疫苗的疗效。LAIV 的 1 剂疗效为 2 剂疗效的 87%至 92%。在第 2 年进行单剂加强免疫时，第 1 年接种 1 剂或 2 剂的儿童在第 2 年的疗效无显著差异（第 1 年接种 1 剂，疗效 64.1%[95%CI，13.1%至 85.7%]；第 1 年接种 2 剂，疗效 55.4%[95%CI，-23.6%至 85.9%]；P=NS）。LAIV 第 1 剂引起的所有不良反应在第 2 剂后均减轻，咳嗽除外。
LAIV 单剂接种可显著预防既往未接种流感疫苗的儿童感染流感，但效果并不理想。对于可能部分免疫的儿童，这一发现可能尤为重要。
