The quarantine of identified close contacts has been vital to reducing transmission rates and averting secondary infection risk before symptom onset and by asymptomatic cases. The effectiveness of this contact tracing strategy to mitigate transmission is sensitive to the adherence to quarantines, which may be lower for longer quarantine periods or in vaccinated populations (where perceptions of risk are reduced). This study develops a simulation model to evaluate contact tracing strategies based on the sequential testing of identified contacts after exposure as an alternative to quarantines, in which contacts are isolated only after confirmation by a positive test. The analysis considers different number and types of tests (PCR and lateral flow antigen tests (LFA)) to identify the cost-effective testing policies that minimize the expected infecting days post-exposure considering different levels of testing capacity. This analysis suggests that even a limited number of tests can be effective at reducing secondary infection risk: two LFA tests (with optimal timing) avert infectiousness at a level that is comparable to 14-day quarantine with 90\% adherence; adding a third test (PCR or LFA) reaches the efficiency of a 95\% quarantine adherence. These results are robust to the exposure dates of the contact, which suggests that simple testing rules can be effective for improving contact tracing in settings where strict quarantine adherence is difficult to implement.
翻译:对已查明的密切接触进行检疫,对于降低传染率和避免症状发作前和无症状病例前的二次感染风险至关重要。这一接触追踪战略在减少传播方面的效力对检疫的坚持性十分敏感,在较长的检疫期或接种疫苗的人群中,这种遵守程度可能较低(在降低风险感知的情况下);这项研究开发了一个模拟模型,根据对接触后已查明接触的连续测试作为检疫的替代方法,评价接触追踪战略,接触只有在经过积极测试后才能分离。分析考虑到不同数量的和种类的检验(PCR和横向流动抗原试验),以确定成本效益高的检验政策,在考虑到不同水平的检测能力的情况下,最大限度地减少预期的接触后几天感染。这项分析表明,即使数量有限的检测也能够有效地减少二次感染风险风险:两次LFA测试(有最佳时机)避免传染性,其程度相当于14天的检疫,但有90 ⁇ 的坚持度;加上第三次检测(PCR或LFA)达到遵守95 ⁇ 检疫措施的效率。这些检测结果可靠地符合接触接触的严格日期,这表明,在严格的接触环境中进行简单的检查规则。