An international group of scientists estimates that the mean infection-to-symptom-onset incubation period of the 2022 global mpox outbreak was similar to that of previous outbreaks, but the onset-to-onset serial interval was about 5 days shorter in 2022. The serial interval is the time between when symptoms first appear in an initial patient and in the person he or she infects.
The findings are published in Emerging Infectious Diseases and may suggest that the shift to a predominantly sexually associated mode of transmission in 2022 may have influenced the serial interval, as well as more public health awareness and surveillance during the global outbreak.
Mpox outbreaks recorded since the 1950s have been defined by household transmission patterns and small case counts, but in the 2022 outbreak the virus became predominantly transmitted through sexual encounters between men who have sex with men.
Shorter onset-to-onset by 1 week
In the study, the authors compared transmission and onset data in 15 studies with a total of 42 case records from pre-2022 mpox outbreaks with data from 42 relevant studies conducted during the 2022 outbreak.
They found that the incubation period was 8.1 days in 2022 and 8.2 days in previous outbreaks, but the serial interval was 8.7 days in 2022 and 14.2 days in previous years.
Our study highlights the importance of monitoring temporal changes in transmission and disease progression.
The authors conclude, "Because estimated values of epidemiologic parameters are often used to inform interventions against a range of pathogens, our study highlights the importance of monitoring temporal changes in transmission and disease progression."
