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

Rapid growth of the B.1.617.2 variant of SARS-CoV-2 has been observed in many countries. Broadly, the factors driving the recent rapid growth of COVID-19 cases could be attributed to shorten generation intervals or higher transmissibility (effective reproduction number, R), or both. As such, establishing reasons for the observed rapid growth will allow countries to know how best to enhance their outbreak control measures. In this study, we analysed the serial interval of household transmission pairs infected with SARS-CoV-2 B.1.617.2 variant and compared with those who were infected prior to the occurrence of the major global SARS-CoV-2 variants. After controlling for confounding factors, our findings suggest no significant changes in the serial intervals for SARS-CoV-2 cases infected with the B.1.617.2 variant. This in turn lends support for a hypothesis of a higher R for B.1.617.2 cases.