Can schools be kept safe even though the COVID-1
Yesterday, the CDC released a detailed look at the proliferation of SARS-CoV-2 within a single school system in rural Wisconsin. While the results come from a time before the new, more easily dispersed tribes had evolved, they show that some of the measures outlined in guidelines on how to safely reopen schools are working. Thanks to these precautions, infections in the school had decreased by 37 percent compared to infections in the community as a whole and there were very few infections occurring within the school. But it also raises an obvious question: If these measures work, why do we not use them all?
The study started in late August 2020 and continued until the end of November. It focused on schools in Wood County, Wisconsin, and tracked infections that occurred among its faculty and staff as well as comparing them to the spread of the pandemic in the county as a whole. In total, there were 4,876 students and 654 employees included in the data.
The schools took many of the steps that experts had advised before the start of the school year. Each student was given several face masks when they started, and wearing a mask was mandatory throughout the period. Compliance with this rule, based on surveys of teachers, was consistently over 90 percent. (However, the report notes that not all teachers returned these reports, so there is a chance that the data lacks the classrooms where compliance was lower.)
Apart from the masks, the schools kept class sizes small with 20 students or less. And these student groups were kept together all day instead of mingling during the day. All students who had COVID-19 symptoms were sent home to isolate, and any siblings they had were also kept from going to school. The report has no information on whether changes in classrooms – increased student segregation or improved ventilation – were also included in the package of precautions taken. But in general, these policies are in line with health authorities’ recommendations for safe schooling.
Out of control
And the schools were put to the test. As with most of the rest of the United States, COVID-19 cases exploded in the county in the fall. At times, Wood County had a 40 percent positivity rate, meaning that four out of every 10 tests for SARS-CoV-2 gave a positive result. This is taken as an indication that there are far more positive cases at the same time that were not detected.
Overall, the number of cases among students and staff was significantly lower than in the surrounding community. The rate in the surrounding towns during the period was almost 5,500 cases per year. 100,000 people. In contrast, students and staff had a rate of 3,450 cases per year. 100,000 people. This corresponds to a total of 191 cases: 133 among students and 58 among employees.
Contact tracking indicates that only seven of these cases were picked up via transmission at the school, where all involved student-to-student dissemination. All seven of these cases involved spread among students in the same class group. In fact, three of them appeared in a single class group. The lack of spread between class groups is a reassuring validation of this strategy.
The main limitation of the analysis is that the test capacity was clearly not sufficient to have kept pace with the spread of infections during this study period. There is a very good chance that some asymptomatic cases were missed in school during this period, which may affect the conclusions from the contact tracking part of the experiment. As such, the seven cases assigned to dissemination in school should be considered as a lower limit.
There are a few ways to look at this data. The first few are the obvious ones: it is not impossible to eliminate the risk during an out-of-control pandemic. However, with appropriate precautions, it is possible to limit the risk to students and severely limit the chances of catching new infections in school.
But the main message is that it is impossible to separate the students from the larger community. While infections among students were down relative to the wider population, a significant number of students settled with SARS-CoV-2, and most of these infections came during interactions that took place outside the school system. Which raises the obvious question of whether the wider population would have benefited from applying more of the practices used by the schools.
As more infectious strains become widespread and vaccine distribution struggles to move forward, it is important that we adopt everything that can be done to limit the spread in the meantime.