In a new study, researchers found that as of October 2020, people aged 20-49 were the only groups sustaining COVID-19 transmission with reproduction numbers well above 1 in the US.
The research was conducted by the Imperial College COVID-19 Response team.
Following initial declines, numbers of COVID-19 cases started to rise again halfway through 2020 in the United States and Europe.
In September the team published their report 32, using age-specific mobility data from across the United States and linking these to age-specific COVID-19 mortality.
Their findings pointed out that targeting interventions to adults aged 20-49 could facilitate the safe reopening of schools and kindergartens.
The new study includes new data up to October 2020.
The updated analysis of aggregated age-specific mobility data from more than 10 million individuals in the US, shows that 65 of 100 COVID-19 infections still originated from individuals aged 20-49 in the US.
Across the US as a whole, the mobility trends indicate substantial initial declines in venue visits followed by a subsequent rebound for all age groups.
In contrast with the large fluctuations in the share of age groups among reported COVID-19 cases, the study describes the share of age groups among the observed COVID-19 deaths remarkably constant.
The researchers found that in locations where novel highly-transmissible SARS-CoV-2 lineages have not yet established, additional interventions among adults aged 20-49, such as mass vaccination with transmission-blocking vaccines, could bring resurgent COVID-19 epidemics under control and avert deaths.
The team says that this study is important because we demonstrate that adults aged 20-49 are the only age groups that have consistently sustained COVID-19 spread across the US, despite large variations in the scale and timing of local epidemics.
Thus—at least where highly transmissible variants have not established—additional interventions targeting the 20-49 age group could bring the epidemics under control.
One author of the study is Dr. Samir Bhatt from Imperial College London.
The study is published in Science.
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