Outbreak Associated with SARS-CoV-2 B.1.617.2 (Delta) Variant in an Elementary School — Marin County, California, May–June 2021

Abstract

MCPH) was notified by an elementary school that on May 23, an unvaccinated teacher had reported receiving a positive test result for SARS-CoV-2, the virus that causes COVID-19. The teacher reported becoming symptomatic on May 19, but continued to work for 2 days before receiving a test on May 21. On occasion during this time, the teacher read aloud unmasked to the class despite school requirements to mask while indoors. Beginning May 23, additional cases of COVID-19 were reported among other staff members, students, parents, and siblings connected to the school. To characterize the outbreak, on May 26, MCPH initiated case investigation and contact tracing that included whole genome sequencing (WGS) of available specimens. A total of 27 cases were identified, including that of the teacher. During May 23-26, among the teacher's 24 students, 22 students, all ineligible for vaccination because of age, received testing for SARS-CoV-2; 12 received positive test results. The attack rate in the two rows seated closest to the teacher's desk was 80% (eight of 10) and was 28% (four of 14) in the three back rows (Fisher's exact test; p = 0.036). During May 24-June 1, six of 18 students in a separate grade at the school, all also too young for vaccination, received positive SARS-CoV-2 test results. Eight additional cases were also identified, all in parents and siblings of students in these two grades. Among these additional cases, three were in persons fully vaccinated in accordance with CDC recommendations (1). Among the 27 total cases, 22 (81%) persons reported symptoms; the most frequently reported symptoms were fever (41%), cough (33%), headache (26%), and sore throat (26%). WGS of all 18 available specimens identified the B.1.617.2 (Delta) variant. Vaccines are effective against the Delta variant (2), but risk of transmission remains elevated among unvaccinated persons in schools without strict adherence to prevention strategies. In addition to vaccination for eligible persons, strict adherence to nonpharmaceutical prevention strategies, including masking, routine testing, facility ventilation, and staying home when symptomatic, are important to ensure safe in-person learning in schools (3).

In-person schooling and associated COVID-19 risk in the United States over Spring Semester 2021

“…Overall, our findings support previous studies that have shown secondary transmission and outbreaks associated with in-person schooling and child care (22)(23)(24)(25)(26). While there are other studies that have shown relatively low risk of transmission in schools (27)(28)(29)(30)(31), SARS-CoV-2 mitigation measures were in place in each of these settings.…”

The Advisory Committee on Immunization Practices’ Interim Recommendation for Use of Pfizer-BioNTech COVID-19 Vaccine in Children Aged 5–11 Years — United States, November 2021

“…*** In addition, children aged 5-11 years represent a growing proportion of new COVID-19 cases reported to CDC, accounting for 10.6% of infections for the week of October 10, 2021, although children aged 5-11 years represent 8.7% of the population (4). In addition, children can contribute to transmission of SARS-CoV-2 in households and communities (5,6). A study of residual *** https://covid.cdc.gov/covid-data-tracker/#mis-national-surveillance sera from commercial laboratories in 47 U.S. jurisdictions estimated the seroprevalance in this age group to be 38% as of September 2021 (7).…”

MITIGATING THE 4th WAVE OF THE COVID-19 PANDEMIC IN ONTARIO

“…In-person education is an essential priority for the overall wellbeing, psychosocial development, and educational development of children [1,67,68], but it also increases the absolute number of contacts for children. School-based policies such as student cohorts, small class sizes, improved ventilation, routine testing, and vaccine mandates for teachers and staff can reduce in-school transmission [68,69].…”