The COVID-19 pandemic caused by the highly infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected over 38 million people worldwide since its emergence in late December 2019 in Wuhan, China. One of the earliest measures of preventing the spread of the infection was school closures around the world. In most countries, closures were adopted.
Now, ten months into the pandemic, schools are cautiously reopening in some countries. Researchers led by Courtney Shelley from the Analytics, Intelligence, and Technology Division, Information Systems and Modeling Group, Los Alamos National Laboratory, New Mexico, United States of America, worked on mathematical predictions that could predict the safety of reopening schools in the U.S. Their study titled, “Safely Reopening K-12 Schools During the COVID-19 Pandemic,” is published preprint at the website medRxiv*.
The World Health Organization (WHO) declared the COVID-19 pandemic on 11 March this year. Within a week following 100,000 COVID-19 cases worldwide (a milestone reached on 7 March 2020), all schools in the USA closed for an early Spring Break and have remained closed for the most of this year now.
The closures were to stop the transmission of the virus from person to person. This was based on the knowledge of the spread of other viruses such as influenza between children at school. Evidence showed that kids were less likely than adults to become infected. This was corroborated by the Centers for Disease Control and Prevention (CDC) that found that between 12 February and 2 April 2020, less than 2 percent of the cases of COVID-19 were children. Children make 22 percent of the U.S. population. This was reported by the CDC COVID-19 Response Team 2020. The United Kingdom, however, did not show differences in infection rates among kids and adults.
Schools opened briefly in Israel and had to be closed within two weeks when safety guidelines to prevent the spread of the infection could not be followed. School closures were associated with several problems such as food insecurity (in several developing nations), slow educational growth, developmental harms, overburdening mothers with work and child care, etc.
Schools were allowed to reopen in certain regions with safety norms:
- social distancing of at least six feet
- lower teacher-student ratios
- isolation and discharge of children who fall ill during school hours
Reopenings of schools in the U.S.
Many school districts and state Departments of Education in the U.S. suggest “hybrid” or “blended rotation” of school openings that involve one group of students to receive in-campus face-to-face instruction. In contrast, the other group of students of the same class undertakes distance learning. Some schools and educational experts suggest full in-person schooling while observing all pandemic precautions of social distancing and mask usage.
What was done in this study?
This study looked at the school reopening plans from different U.S. regions and districts and identified common factors. Some of the popular reopening plans the researchers write include:
- “traditional five-day per week attendance at 100% school capacity.”
- “two cohort half-capacity plans with students alternating days in attendance.”
- “one day per grade, 20% capacity plans.”
Most schools are in favor of the “hybrid” or “blended rotation,” they found.
This study looked at the possible impacts of each of these types of reopening plans. Since real-world data is absent, the team of researchers used mathematical modeling to predict the impact of such measures. They looked at a 100,000-person community along with 15,000 school-aged children, all being susceptible to COVID-19 infection. A single susceptible individual is replaced with an infected person, and modeling is used to predict the impact of reopening schools.
Results or findings of the study
- The basic model – involves no school reopening, and all are equally susceptible. Here transmission is possible via three routes, “from clinically infectious cases, from subclinically infectious cases at a potentially reduced rate, and from preclinically infectious cases at a known reduced rate.” Authors found, “In the baseline model under initial conditions with no schooling, a total of 60,089.49 (95% CI: 47,355.81, 72,823.17) clinical infections occur in a community of 100,000 individuals.”
- School reopening plans – Here, the 15,000 children among the population attends school in five days a week plan. The results found, “Increased consecutive days in school offers a slight reduction in the total number of cases compared to the baseline of no schooling by delaying exposure between cohorts.”
- Two cohort plans – One group or cohort attends school on-campus while other groups remain in their current distance learning plan. Authors of the study write their findings, stating, “Split cohort plans, in general, are very robust against introduced infectious cases, especially when the initial infection occurs within the town rather than the school population.”
- Five cohort plan – Here, each grade uses the school facilities for a single day of in-person instruction. Results were shown as, “Under uncontrolled conditions, the 20% capacity, Five Cohort school reopening plan reduces total infections from 59,942.76 in the distance learning baseline to 176.90... when the converted infectious individual is in town.”
Speaking about the last plan, the authors wrote that this would be most feasible and effective for elementary schools than middle schools or high schools. In the latter two groups, there is little intermingling and risk of spread of infection, they wrote.
Conclusions and implications
The authors concluded that “The "Five-Day Switch" plan, which separates students into two cohorts, each of whom attends in-person learning for five consecutive days followed by five days of distance learning, best captures these protective attributes.” The researchers are working on their follow up study where they are analyzing the most promising scenarios to assess which parameters could help prevent transmission of the infection to the maximum.
This study was funded by the Laboratory Directed Research & Development funds (Los Alamos National Laboratory).
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.