More than three years after the start of the COVID-19 epidemic, mathematical modeling is still providing us with valuable insights, as shown in a recent study on household transmission of SARS-CoV-2 by the Hong Kong University School of Public Health and the Institut Pasteur/Université Paris Cité. Scientists believe that there is a subset of individuals with SARS-CoV-2 who are three times more likely to spread the virus to other individuals than the average person.