Age-Specific Resurgence of COVID-19 in the US

The resurgent epidemics of SARS-CoV-2 in 2020 may be explained by a shift in contact patterns, with transmission primarily driven by working adults aged 20 to 49 years, according to a study published in Science.  

In mid-2020, the US experienced a sustained resurgence in the transmission of COVID-19 after initial declines. Throughout the epidemic, there were significant variations among states in terms of mortality, infection rates, and the types and strictness of interventions. Yet, the relationship between interventions, contact patterns, infections, and demographic factors was poorly understood, highlighting the need for age-specific mobility data for studying these dynamics effectively.  

“In this study, we use detailed mobile-phone data from more than 10 million individuals and establish a mechanistic relationship between individual contact patterns and COVID-19 mortality data,” explained researchers.  

As of October 29, 2020, scientists found that adults between the ages of 20 and 34 and 35 and 49 have higher transmission rates of spreading the SARS-CoV-2 virus than other age groups. Sustained transmission rates for adults were linked to rebounding mobility over the summer and elevated transmission risks per venue visit.  

School reopenings led to modest shifts in resurgent COVID-19, with less than 5% of transmissions attributable to children aged 0 to 9 years and less than 10% to early adolescents and teenagers aged 10 to 19. However, since children and teenagers may spread infections among more transmission efficient, researchers estimated that school opening was indirectly associated with a 26% increase in SARS-CoV-2 transmission overall. 

“Our key conclusion is that in locations where novel, highly transmissible SARS-CoV-2 lineages have not yet become established, additional interventions among adults aged 20 to 49, such as mass vaccination with transmission-blocking vaccines, could bring resurgent COVID-19 epidemics under control and avert deaths,” said researchers.  

Reference:

Monod M, Blenkinsop A, et al. Age groups that sustain resurging COVID-19 epidemics in the United States. Science. 2021;371(6536). doi:10.1126/science.abe8372.