在疫苗问世之前的年代,全球均有麻疹。 英国每年报道病例数在160 000到800 000,每2年出现一次流行高峰。[2]Public Health England. Immunisation against infectious disease: the Green Book. September 2014 [internet publication].https://www.gov.uk/government/collections/immunisation-against-infectious-disease-the-green-book 在美国,每 2-5 年会出现一次流行,每年报道的病例数为 200,000 到 400,000,但是实际上每一个约 4 百万儿童的出生队列中几乎每名儿童均有感染。5-9 岁儿童最易感染,发病率无性别差异。[1]Cherry JD. Measles virus. In: Cherry JD, Demmler-Harrison GJ, Kaplan SL, et al, eds. Textbook of pediatric infectious diseases. 7th ed. Philadelphia, PA: Saunders; 2014:2373-94. 麻疹疫苗于1960年代问世,疫苗接种使麻疹病例报道数减少了99%以上。 推荐接种两次麻疹疫苗以确保免疫力。[3]World Health Organization. Measles. February 2013 [internet publication].http://www.who.int/mediacentre/factsheets/fs286/en/ 芬兰于1982年起采用接种两次麻腮风疫苗,并始终保持高覆盖度。 其本土麻疹已于1994年被消灭。[4]Peltola H, Heinonen OP, Valle M, et al. The elimination of indigenous measles, mumps and rubella from Finland by a 12-year two-dose vaccination program. N Engl J Med. 1994;331:1397-402.http://www.nejm.org/doi/full/10.1056/NEJM199411243312101#t=articlehttp://www.ncbi.nlm.nih.gov/pubmed/7969278?tool=bestpractice.com
在美国,从1994年开始大多数病例为输入性或与输入性相关。[1]Cherry JD. Measles virus. In: Cherry JD, Demmler-Harrison GJ, Kaplan SL, et al, eds. Textbook of pediatric infectious diseases. 7th ed. Philadelphia, PA: Saunders; 2014:2373-94. 在2000年,美国宣布消灭麻疹。
美国于 2014 年报告了 667 例麻疹病例,这是自 2000 年记录到麻疹消除后的最高病例数。接下来的数年中,每年的发病例数下降到200以下,直到2018年又达到372例,但未经证实。在2019年的首月及其后半月间,美国报道了127例,超过了2017年发病总例数。[5]Centers for Disease Control and Prevention. Measles cases and outbreaks. February 2019 [internet publication].https://www.cdc.gov/measles/cases-outbreaks.html 大多数感染发生于未经免疫接种的人群。经确认,归国旅行者为暴发来源。[6]Hyle EP, Rao SR, Jentes ES, et al. Missed opportunities for measles, mumps, rubella vaccination among departing U.S. adult travelers receiving pretravel health consultations. Ann Intern Med. 2017 Jul 18;167(2):77-84.http://www.ncbi.nlm.nih.gov/pubmed/28505632?tool=bestpractice.com
在世界范围内,麻疹仍是一种常见传染病。世界卫生组织 (World Health Organization, WHO) 报告称,麻疹在 WHO 欧洲区域已出现反弹。[7]World Health Organization. Europe observes a 4-fold increase in measles cases in 2017 compared to previous year. February 2018 [internet publication].http://www.euro.who.int/en/media-centre/sections/press-releases/2018/europe-observes-a-4-fold-increase-in-measles-cases-in-2017-compared-to-previous-year 在2016年创新低记录的5273例之后,47个欧洲地区国家的82,500名儿童和成人在2018年感染麻疹,72名儿童和成人因感染而死亡。[8]World Health Organization. Measles in Europe: record number of both sick and immunized. February 2019 [internet publication].http://www.euro.who.int/en/media-centre/sections/press-releases/2019/measles-in-europe-record-number-of-both-sick-and-immunized
缺乏免疫接种计划,该疾病就将普遍存在。虽然免疫接种计划显著降低了全球疾病负担,全球麻疹死亡病例由 2000 年的 550,100 例减少至 2016 年的 89,780 例,但麻疹仍是 5 岁以下儿童疫苗可预防性疾病死亡的一种主要原因,也是导致合并症的一个重要因素。[9]Strebel PM, Papania MJ, Dayan GH, et al. Measles vaccine. In: Plotkin SA, Orenstein WA, Offit PA, eds. Vaccines. 6th ed. Philadelphia, PA: Elsevier; 2013:352-87.[10]World Health Organization. Immunization, vaccines and biologicals: measles. November 2017 [internet publication].http://www.who.int/immunization/diseases/measles/en/大多数因麻疹而导致的发病率和死亡率发生于基础卫生设施较差的低收入国家。[10]World Health Organization. Immunization, vaccines and biologicals: measles. November 2017 [internet publication].http://www.who.int/immunization/diseases/measles/en/