Serial intervals in SARS-CoV-2 B.1.617.2 variant cases

In particular, an increase in observed growth rate of COVID-19 cases could be the result of a shorter generation interval (ie, the delay from one infection to the next) or an increase in the effective reproduction number, R, of an infected individual (ie, the average number of secondary cases generated by an infectious individual), or both.2 Whereas a shorter generation interval would increase the speed but not the number of individual-level transmissions, a larger value of R would require both faster and wider coverage of outbreak control measures such as vaccination or physical distancing to suppress transmission. Without signs of lowered disease severity for the B.1.617.2 variant, contact tracing and testing around COVID-19 cases, along with vaccination and non-pharmaceutical interventions, continue to remain key SARS-CoV-2 outbreak control measures in the short term. The model code and de-identified data that underlie the results reported in this Correspondence are available online at https://github.com/rachaelpung/serial_interval_covid_b.1.617.2.