实施预防接种的关键问题是:免疫能持续多久?回答这个问题涉及到瑞典1967年开始对有脊灰预防接种的组群分析研究。自从1957年开始接种以来,瑞典便只使用灭活脊灰疫苗(IPV)。实际上早在1962年野毒脊灰病毒已停止了流行,因此不存在预期的“天然”加强免疫。由于瑞典有发展良好的医疗卫生事业,为长期随访研究提供了很好的机会。从瑞典不同地区登记了数百名儿童以便研究。 The key question for implementing vaccination is: How long will the immunization last? The answer to this question concerns the group analysis of polio vaccination started in Sweden in 1967. Sweden has used only the Inactivated Polio Vaccine (IPV) since its inception in 1957. In fact, as early as 1962, the wild-type poliovirus has ceased to be epidemic, so there is no expected “natural” boost. Thanks to the well-developed health care in Sweden, this provides a good opportunity for long-term follow-up studies. Hundreds of children were enrolled from different parts of Sweden for research.