Classroom contact may lead to Covid-19 spread, warns CDC while medical body says schools should reopen by fall
Widespread school closures have mostly eliminated the risk for classroom transmission of coronavirus, says the agency’s report
Classroom interaction between a teacher and students could lead to coronavirus transmission, warns the US Centers for Disease Control and Prevention (CDC). The agency’s report describes a case where a teacher who had Covid-19 may have infected students after returning to the classroom while still experiencing symptoms. The study comes at a time when the American Academy of Pediatrics (AAP) has updated its guidance for school reentry to say that children should be physically present in school for their well-being and the most effective learning and that schools should aim to reopen by fall.
In late February 2020, a teacher experienced headache, sore throat, muscle pain and fatigue while traveling in Europe, where community transmission of Covid-19 was ongoing. After arriving back in the US, the teacher returned to school from February 24-27 while experiencing the same symptoms besides a limited cough. She tested positive for SARS-CoV-2, the virus that causes Covid-19. All students who attended classes with the infected teacher were instructed to quarantine themselves at home through March 12.
After the quarantine period, the CDC conducted a serologic survey to assess potential Covid-19 transmission in a classroom setting. A serologic test is a blood test that looks for signs of a previous infection. During February 24-27, the teacher taught 16 classes, all in the same room, each with less than 30 students. Of the 16 classes, 10 were interactive classes. This implies that they were discussion-based, in which the teacher reported walking around the room and speaking directly with students.
The other 6 classes were non-interactive in which the teacher sat mostly in one location and close interactions with students were limited. "On March 10, we contacted 120 students (48 or 40%) enrolled in interactive classes, and 72 or 60% enrolled in non-interactive classes, whose only known exposure was through classroom contact with the teacher and invited them to participate in our serologic survey. 21 (18%) students volunteered," says the report.
The average age of the students was 17 years (range 5-18 years). Five (24%) had interactive classroom contact where the average in-class time was 108 minutes. Sixteen (76%) participants had non-interactive classroom contact with an average in-class time of 50 minutes.
Out of five students who had been in interactive classes and participated in the CDC study, results for 2 students suggest they had been previously infected with Covid-19. "Results for student A were positive and for student B indeterminate. Students A and B were not in the classroom during the same period and sat in different locations in the classroom," says the study. One of those students (student A) experienced symptoms for nine days, including muscle aches, runny nose and cough and the other student had no symptoms. Two other students from the five in the interactive classes had no serological evidence that suggests they had been infected in the past, but they had reported mild symptoms – one had fever and headache that lasted one day and another had a runny nose that lasted one day.
Of the 16 students who were in the non-interactive classes and participated in the study, seven reported symptoms, including sore throat, headache, runny nose and muscle pain. But antibody tests found no evidence of a previous Covid-19 infection.
"Although SARS-CoV-2 transmission from symptomatic persons to close contacts has been well established, we evaluated risks associated with classroom contact. The positive results for student A suggest past infection with SARS-CoV-2. The meaning of the indeterminate result for student B is less clear in this context, but this result may be suggestive of past infection. We do not know whether results from student A or B are indicative of immunity to SARS-CoV-2 infection," says the study. It adds, "Widespread school closures have mostly eliminated the risk for classroom transmission of SARS-CoV-2. However, these results suggest that classroom interaction between an infected teacher and students might result in virus transmission."
In-person learning in school is critical, says AAP
The American Academy of Pediatrics is "strongly advocating" that all policy considerations for the coming school year should start with the goal of having students physically present in school. It says that schools are "fundamental to child and adolescent development and well-being" and provide children and adolescents with academic instruction, social and emotional skills, safety, reliable nutrition, physical/speech, and mental health therapy, and opportunities for physical activity, among other benefits.
"The importance of in-person learning is well-documented, and there is already evidence of the negative impacts on children because of school closures in the spring of 2020. Lengthy-time away from school and associated interruption of supportive services often result in social isolation, making it difficult for schools to identify and address important learning deficits as well as child and adolescent physical or sexual abuse, substance use, depression, and suicidal ideation," says the medical body.
It further explains, “This, in turn, places children and adolescents at considerable risk of morbidity and, in some cases, mortality. Beyond the educational impact and social impact of school closures, there has been a substantial impact on food security and physical activity for children and families."
The AAP has listed several re-entry policies for schools to follow as they prepare for the fall semester amid the coronavirus pandemic. The body also says that policymakers should acknowledge that Covid-19 policies are intended to mitigate, not eliminate risk and that no single action or set of actions will completely eliminate the risk of Covid-19 transmission. Instead, AAP recommends implementing several "coordinated interventions" to reduce the risk. "For example, where physical distance cannot be maintained, students (over the age of 2 years) and staff can wear face coverings (when feasible). Education for the entire school community regarding the measures should begin early, ideally at least several weeks before the start of the school year," it recommends.
The group says that policymakers must consider the "mounting evidence" regarding Covid-19 in children and adolescents, including the role they may play in the transmission of the infection. The AAP says evidence shows that while children and adolescents play a major role in amplifying influenza outbreaks, this does not appear to be the case with Covid-19. The group adds that while there are still many questions about the virus, evidence indicates that children are less likely to become infected and spread infection.
"SARS-CoV-2 appears to behave differently in children and adolescents than other common respiratory viruses. Although many questions remain, the preponderance of evidence indicates that children and adolescents are less likely to be symptomatic and less likely to have severe disease resulting from SARS-CoV-2 infection. Besides, children may be less likely to become infected and to spread infection. Policies to mitigate the spread of Covid-19 within schools must be balanced with the known harms to children, adolescents, families, and the community by keeping children at home," says the statement.