A new study shows that during the first two years of the COVID-19 pandemic in Quebec, over seven epidemic waves, SARS-CoV-2 tended to first infect young adults before the rest of the population.
That makes them a key demographic to watch as public health officials try to see new waves of this and other viruses coming, says the University of Montreal research team behind the study.
“Our results indicate that young adults could serve as an early indicator of emerging community transmission,” notes Kate Zinszer, epidemiologist and associate professor at the UdeM School of Public Health (ESPUM). Monitoring trends within this age group could help public health authorities recognize new waves earlier and respond more quickly to limit the spread of the virus.
Throughout the pandemic, cases of COVID-19 generally occurred within specific clusters: ethnic, geographic or socioeconomic. However, health officials struggled to determine how these outbreaks appeared and what the affected people had in common.
Using COVID-19 surveillance data in Quebec, collected between February 2020 and August 2022 and covering seven waves of the crisis, Professor Zinszer and her colleagues targeted characteristics associated with the risk of being among the first cases in an outbreak.
Their results showed that young adults were consistently at higher risk of being the first cases of large community outbreaks, suggesting that closer monitoring of COVID-19 incidence in this age group could be crucial for early detection of emerging outbreaks or new waves.
“Overall, our study provides valuable information to public health authorities by helping to designate priority groups at the front line of the emergence of outbreaks and supporting the implementation of tailor-made and adaptive interventions,” write the co-authors of the study, which include Kate Zinszer and her colleagues from ESPUM Adrien Saucier (first author) and Katia Charland, as well as Élise Fortin and Christine Lacroix, from the Institut national de public health of Quebec.
The results of the study were recently published in the journalSpatial and Spatio-temporal Epidemiology.