In an effort to mitigate the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), North Carolina closed prekindergarten through grade 12 public schools to in-person instruction on March 14, 2020. On July 15, 2020, North Carolina’s governor announced schools could open via remote learning or a hybrid model that combined in-person and remote instruction. In August 2020, 56 of 115 North Carolina school districts joined The ABC Science Collaborative (ABCs) to implement public health measures to prevent SARS-CoV-2 transmission and share lessons learned. We describe secondary transmission of SARS-CoV-2 within participating school districts during the first 9 weeks of in-person instruction in the 2020–2021 academic year.
From August 15, 2020 to October 23, 2020, 11 of 56 school districts participating in ABCs were open for in-person instruction for all 9 weeks of the first quarter and agreed to track incidence and secondary transmission of SARS-CoV-2. Local health department staff adjudicated secondary transmission. Superintendents met weekly with ABCs faculty to share lessons learned and develop prevention methods.
Over 9 weeks, 11 participating school districts had >90 000 students and staff attend school in person. Among these students and staff, 773 community-acquired SARS-CoV-2 infections were documented by molecular testing. Through contact tracing, health department staff determined an additional 32 infections were acquired within schools. No instances of child-to-adult transmission of SARS-CoV-2 were reported within schools.
In the first 9 weeks of in-person instruction in North Carolina schools, we found extremely limited within-school secondary transmission of SARS-CoV-2, as determined by contact tracing.
Thank you for your thoughtful comment. As we learn more about variants we will certainly need to reassess mitigation strategies and the closely monitor for changes in transmissibility that might serve to limit the applicability of our current results. The B.1.1.7 variant has a mutation in the spike protein which allows more efficient binding and facilitating viral entry. This more efficient cellular entry is thought to explain the documented increased transmissibility. Thus, it is critical that mitigation measures which reduce person-to-person transmission remain at the forefront, as prevention of spread of infection through distancing and mask wearing will be critical to prevent transmission of this more efficient variant.
Thank you for your comment. As we described in the paper, adjudication of cases was left to each district's public health officials. Daily symptom monitoring was conducted in schools, and symptomatic students were asked to go to free testing sites identified by the school district. Upon identification of a case, contact tracing was conducted to adjudicate the infection as either primary (community acquired) or secondary (acquired within school setting). These data were then reported by district superintendents as aggregated data to ABC faculty. This was specifically to protect potentially identifiable information, as several schools had low numbers of infections. All close contacts were recommended to undergo testing and free testing sites were identified by the school district (see attached sample letter and schedule from one of the districts as an example). We do not have access to the number of close contacts who underwent testing, in part because mandated testing was not required by the study. As stated in the manuscript, non-mandated testing is a limitation of these data.
Well done. This informative paper concludes, "Our data indicate that schools can reopen safely if they develop and adhere to specific SARS-CoV-2 prevention policies." This seems right based on the data at hand for the period of investigation, but do the authors think that the findings will generalize to a situation where possibly more infectious variants like B.1.1.7 are spreading? Are there limits to this guidance?
Well done. This informative paper concludes, "Our data indicate that schools can reopen safely if they develop and adhere to specific SARS-CoV-2 prevention policies." This seems right based on the data at hand for the period of investigation, but do the authors think that the findings will generalize to a situation where possibly more infectious variants like B.1.1.7 are spreading? It would be useful to include a discussion of this in the final print version.
Is the >1/1000 number correct? Aren't we measuring out of 100,000? That seems to be a mistake. Please educate me if I am totally off base.
It is unclear to me how exactly confirmed cases were separated into primary (presumably this means acquired by community transmission) and secondary cases (presumably this means acquired by in-school transmission) . There is almost no information in the paper about this, nor is there a discussion of associated uncertainties. There is also no information as to the extent of testing and any assessment of what fraction of cases (primary and secondary) might have been missed and how this might/might not impact the conclusions.