Are schools drivers of COVID-19 infections — an analysis of outbreaks in Colorado, USA in 2020

Background The impact of school closures/reopening on transmission of SARS-CoV-2 in the wider community remains contested. Methods Outbreak data from Colorado, USA (2020), alongside data on implemented public health measures were analyzed. Results There were three waves (n = 3169 outbreaks; 61 650 individuals). The first was led by healthcare settings, the second leisure/entertainment and the third workplaces followed by other settings where the trajectory was equally distributed amongst essential workplaces, non-essential workplaces, schools and non-essential healthcare. Non-acute healthcare, essential and non-essential workplace experienced more outbreaks compared to education, entertainment, large-group-living and social gatherings. Schools experienced 11% of identified outbreaks, yet involved just 4% of total cases. Conversely, adult-education outbreaks (2%) had disproportionately more cases (9%). Conclusion Our findings suggest schools were not the key driver of the latest wave in infections. School re-opening coinciding with returning to work may have accounted for the parallel rise in outbreaks in those settings suggesting contact-points outside school being more likely to seed in-school outbreaks than contact points within school as the wave of outbreaks in all other settings occurred either prior to or simultaneously with the schools wave. School re-opening is a priority but requires mitigation measures to do so safely including staggering opening of different settings whilst maintaining low levels of community transmission