Lesson plan
Serial interval
The serial interval in the epidemiology of communicable (infectious) diseases is the time between successive cases in a chain of transmission. The serial interval is generally estimated from the interval between clinical onsets (if observable), in which case it is the 'clinical onset serial interval'. It could in principle be estimated by the time interval between infection and subsequent transmission. If the typical time from the first person's clinical onset to when they infect another is TA, and the incubation period of a subsequent case is IB, then the clinical onset serial interval is TA + IB. More realistically, the calculation would use the observed frequency distribution of times from onset of a single primary case to that of its associated secondary cases. If the distribution of timing of transmission events during the infectious period is not skewed around its mean, then the average serial interval is calculated as the sum of the average latent period (from infection to infectiousness) and half the average infectious period. Serial intervals can vary widely, especially for lifelong diseases such as HIV infection, chickenpox, and herpes. The serial interval for SARS was 7 days. For the original strain of COVID-19, a 2020 review of the published literature shows its serial interval to be 4-8 days.…
Article summary
The serial interval in the epidemiology of communicable (infectious) diseases is the time between successive cases in a chain of transmission. The serial interval is generally estimated from the interval between clinical onsets (if observable), in which case it is the 'clinical onset serial interval'. It could in principle be estimated by the time interval between infection and subsequent transmission. If the typical time from the first person's clinical onset to when they infect another is TA, and the incubation period of a subsequent case is IB, then the clinical onset serial interval is TA + IB. More realistically, the calculation would use the observed frequency distribution of times from onset of a single primary case to that of its associated secondary cases. If the distribution of timing of transmission events during the infectious period is not skewed around its mean, then the average serial interval is calculated as the sum of the average latent period (from infection to infectiousness) and half the average infectious period. Serial intervals can vary widely, especially for lifelong diseases such as HIV infection, chickenpox, and herpes. The serial interval for SARS was 7 days. For the original strain of COVID-19, a 2020 review of the published literature shows its serial interval to be 4-8 days.…
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.