Background In 2020, the Council of State and Territorial Epidemiologists (CSTE) pertussis case definition was modified; the main change was classifying PCR-positive cases as confirmed, regardless of cough duration. Pertussis data reported through Enhanced Pertussis Surveillance (EPS) in seven sites and the National Notifiable Diseases Surveillance System (NNDSS) were used to evaluate the impact of the new case definition. Methods We compared the number of EPS cases with cough onset in 2020 to the number that would have been reported based on the prior (2014) CSTE case definition. To assess the impact of the change nationally, the proportion of EPS cases newly reportable under the 2020 CSTE case definition was applied to 2020 NNDSS data to estimate how many additional cases were captured nationally. Results Among 442 confirmed and probable cases reported to EPS states in 2020, 42 (9.5%) were newly reportable according to the 2020 case definition. Applying this proportion to the 6,124 confirmed and probable cases reported nationally in 2020, we estimated that the new definition added 582 cases. Had the case definition not changed, reported cases in 2020 would have decreased by 70% from 2019; the observed decrease was 67%. Conclusions Despite a substantial decrease in reported pertussis cases in the setting of COVID-19, our data show that the 2020 pertussis case definition change resulted in additional case reporting compared with the previous case definition, providing greater opportunities for public health interventions such as prophylaxis of close contacts.

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评估 2020 年州和地区流行病学家委员会百日咳病例定义对报告的百日咳病例的影响

背景 2020 年，州和地区流行病学家委员会 (CSTE) 修改了百日咳病例定义；主要变化是将 PCR 阳性病例分类为确诊病例，无论咳嗽持续时间如何。通过七个地点的增强百日咳监测 (EPS) 和国家法定疾病监测系统 (NNDSS) 报告的百日咳数据用于评估新病例定义的影响。方法 我们将 2020 年咳嗽发作的 EPS 病例数与根据之前 (2014) CSTE 病例定义报告的数量进行了比较。为了评估这一变化对全国的影响，将根据 2020 年 CSTE 病例定义新报告的 EPS 病例比例应用于 2020 年 NNDSS 数据，以估计全国范围内新增了多少病例。结果 2020 年向 EPS 州报告的 442 例确诊病例和疑似病例中，根据 2020 年病例定义，有 42 例（9.5%）是新报告病例。将此比例应用于 2020 年全国报告的 6,124 例确诊和疑似病例，我们估计新定义增加了 582 例。如果病例定义不改变，2020年报告的病例将比2019年减少70%；观察到的下降幅度为 67%。结论 尽管在 COVID-19 背景下报告的百日咳病例大幅减少，但我们的数据显示，与之前的病例定义相比，2020 年百日咳病例定义的变化导致了更多的病例报告，为公共卫生干预措施（例如预防百日咳）提供了更多机会。密切接触者。