Glass K, Grenfell B T
National Centre for Epidemiology and Population Health, Australian National University, Canberra 0200, Australia.
Vaccine. 2004 Sep 28;22(29-30):4110-6. doi: 10.1016/j.vaccine.2004.02.047.
Following the introduction of vaccination against measles, levels of clinical infection have dropped markedly. As we move further into the vaccine era, increasingly many individuals owe their measles immunity to vaccination and have had few (if any) exposures to wild virus. A number of recent reports suggest that vaccinated individuals with low levels of immunity may be at risk of subclinical measles infection. We explore the interplay between levels of infection and immunity over time using a mathematical model that simulates infection, waning and boosting of immunity. We focus particularly on the situation in England, where vaccination has been in place since 1966. Simulations of our model demonstrate a rise in the levels of subclinical measles infection over time, and a corresponding rise in clinical measles infections if vaccination levels are too low. We compare the impact of intervention strategies, and find that the rise in cases is most effectively reduced by 'catch-up' vaccination of children. In recent years, vaccination levels in England have dropped from above 90% in the 1990s to 84% in 2001/2002. We discuss the impact of declining vaccination levels on clinical and subclinical infections.
随着麻疹疫苗接种的推行，临床感染水平显著下降。随着我们进一步迈入疫苗时代，越来越多的人对麻疹的免疫力源于疫苗接种，几乎没有（如果有的话）接触过野生病毒。最近的一些报告表明，免疫力水平较低的接种者可能面临亚临床麻疹感染的风险。我们使用一个模拟感染、免疫力减弱和增强的数学模型来探讨感染水平与免疫力随时间的相互作用。我们特别关注自1966年以来就实施疫苗接种的英国的情况。我们模型的模拟结果表明，亚临床麻疹感染水平会随时间上升，如果疫苗接种水平过低，临床麻疹感染也会相应增加。我们比较了干预策略的影响，发现通过对儿童进行“补种”疫苗能最有效地减少病例的增加。近年来，英国的疫苗接种率已从20世纪90年代的90%以上降至2001/2002年的84%。我们讨论了疫苗接种率下降对临床和亚临床感染的影响。
