serial interval       
noun [ C ]  medical specialized uk/ˈsɪə.ri.əl ˌɪn.tə.vəl/ us/ˈsɪr.i.əl ˌɪn.t̬ɚ.vəl/
 (传染)间隔时间
the time between someone showing symptoms (= signs) of a disease and a person they infect showing symptoms of the disease
  The serial interval for SARS was 7 days. SARS的传染间隔时间为7天。 
 The serial interval is one of the significant epidemiological measures that determine the spread of infectious disease. 传染间隔时间是流行病学上的一个重要参数,决定了疾病传播的速度。 
 - More examples
 - The serial interval is the time between onsets of epidemiologically related cases.
 - Recent estimates for the mean serial interval of COVID-19 range from 3.9 days to 4.0 days.
 - In epidemiology, serial intervals are measured from when one infected person starts to show symptoms to when the next person infected becomes symptomatic.