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What is serial interval and how can it be managed to control Covid-19?

Topics Covered: Issues related to health.

What is serial interval, and how can it be managed to control Covid-19?

Why in News?

China, which has now gone over a month without any locally transmitted Covid-19 cases, was able to contain Covid-19 due to its ability to manage the serial interval.

What is it?

The serial interval is the duration between symptom onset of a primary case and symptom onset of secondary cases (contacts) generated by the primary case.

In simple terms, the serial interval is the gap between the onset of Covid-19 symptoms in Person A and Person B, who is infected by Person A.

When was it first used?

The term was first used by British physician William Pickles, who had initially referred to it as transmission interval with reference to a hepatitis epidemic in the United Kingdom during 1942-45.

Mains Factors on which Serial Interval depends:

Incubation period: The time between a person’s exposure to the virus and symptom onset.

Reproduction rate or R naught: The number of people who will be infected by one infected person.

Significance? What does changes in serial interval indicate?

The serial interval helps to gauge the effectiveness of infection control interventions besides indicating rising population immunity and forecast future incidence.

Thus, the more quickly persons who contracted Covid-19 are identified and isolated, the shorter the serial interval becomes and cuts down opportunities for transmission of the virus.

What India needs to do?

To manage serial interval, a robust system of contact tracing, quarantine, and isolation protocols should be in place.

Case study:


The serial interval in Wuhan came down from 7.8 days to 2.6 days between early January and early February.

  • Quarantining contacts within 1 day from symptom onset helped reduce Covid-19 transmission by 60 per cent.
  • This was made possible due to aggressive contact tracing, quarantine, and isolation, thereby ensuring that infected patients, because they were isolated, could not infect any more people later in the infection cycle.



Prelims Link:

  1. What is serial interval?
  2. What is R0?
  3. Difference between RNA and DNA.
  4. Differences between RT PCR and antibody tests.
  5. What is a RNA virus? How it survives?
  6. What are antibodies?

Mains Link:

What is serial interval, and how can it be managed to control Covid-19?

Sources: Indian Express.