Sivasankaran Saravanan, Manickam P, Ramakrishnan R, Hutin Y, Gupte M D
National Institute of Epidemiology, Chennai, India.
MMWR Suppl. 2006 Apr 28;55(1):16-9.
As part of the global strategic plan to reduce the number of measles deaths in India, the state of Tamilnadu aims at > or =95% measles vaccination coverage. A study was conducted to measure overall coverage levels for the Poondi Primary Health Center (PPHC), a rural health-care facility in Tiruvallur District, and to determine whether any of the PPHC's six health subcenters had coverage levels <95%.
The Lot Quality Assurance Sampling (LQAS) method was used to identify health subcenters in the PPHC area with measles vaccination coverage levels <95% among children aged 12-23 months. Lemeshow and Taber sampling plans were used to determine that the measles vaccination status of 73 children aged 12--23 months had to be assessed in each health subcenter coverage area, with a 5% level of significance and a decision value of two. If more than two children were unvaccinated, the null hypothesis (i.e., that coverage in the health subcenter was low [<95%]) was not rejected. If the number of unvaccinated children was two or fewer, the null hypothesis was rejected, and coverage in the subcenter was considered to be good (i.e., > or =95%). All data were pooled in a stratified sample to estimate overall total coverage in the PPHC area.
For two (33.3%) of the six health subcenters, more than two children were unvaccinated (i.e., coverage was <95%). Combining results from all six health subcenters generated a coverage estimate of 97.7% (95% confidence interval = 95.7-98.8) on the basis of 428 (97.7%) of 438 children identified as vaccinated.
LQAS techniques proved useful in identifying small health areas with lower vaccination coverage, which helps to target interventions. Monthly review of vaccination coverage by subcenter and village is recommended to identify pockets of unvaccinated children and to maintain uniform high coverage in the PPHC area.
作为印度减少麻疹死亡人数全球战略计划的一部分，泰米尔纳德邦的目标是实现麻疹疫苗接种覆盖率达到或超过95%。开展了一项研究，以衡量蒂鲁瓦勒尔区一家农村医疗保健机构——蓬迪初级卫生中心（PPHC）的总体覆盖率，并确定该PPHC的六个卫生分中心中是否有任何一个的覆盖率低于95%。
采用批量质量保证抽样（LQAS）方法，确定PPHC地区12至23个月龄儿童麻疹疫苗接种覆盖率低于95%的卫生分中心。使用莱梅肖和泰伯抽样计划确定，在每个卫生分中心覆盖区域，必须评估73名12至23个月龄儿童的麻疹疫苗接种状况，显著性水平为5%，判定值为2。如果未接种疫苗的儿童超过两名，则不拒绝原假设（即该卫生分中心的覆盖率较低[<95%]）。如果未接种疫苗的儿童数量为两名或更少，则拒绝原假设，该分中心的覆盖率被视为良好（即≥95%）。所有数据汇总到一个分层样本中，以估计PPHC地区的总体覆盖率。
六个卫生分中心中有两个（33.3%）的未接种疫苗儿童超过两名（即覆盖率<95%）。根据438名被确定为已接种疫苗的儿童中的428名（97.7%），综合六个卫生分中心的结果得出覆盖率估计值为97.7%（95%置信区间=95.7 - 98.8）。
LQAS技术被证明有助于识别疫苗接种覆盖率较低的小范围卫生区域，这有助于确定干预目标。建议每月按分中心和村庄审查疫苗接种覆盖率，以识别未接种疫苗儿童群体，并在PPHC地区维持统一的高覆盖率。
