novel coronavirus was likely circulating undetected for at most two months before the first human cases of Covid-19 were described in Wuhan, China in late-December 2019, according to a study.The research, published in the journal Science, used molecular dating tools and epidemiological simulations to date the emergence of the virus to as early as October 2019.Also Read | Vaccine utilization rates lower in states witnessing second waveThe team, including researchers from University of California San Diego in the US, note that their simulations suggest that the mutating virus dies out naturally more than three-quarters of the time without causing an epidemic."Our study was designed to answer the question of how long could SARS-CoV-2 have.