Does school attendance facilitate greater SARS-CoV-2 spread?

In a recent study published in the Eurosurveillance Journal, researchers performed a descriptive cross-sectional study in Ireland during the academic year 2020–21.

Researchers aimed to capture the reverse transcription-polymerase chain reaction (RT-PCR)-positive coronavirus disease 2019 (COVID-19) cases among all school students and staff.

In addition, they used contact tracing to identify on-site school close contacts of these cases and their RT-PCT test results.

Study: Limited transmission of SARS-CoV-2 in schools in Ireland during the 2020–2021 school year. Image Credit: LBeddoe/Shutterstock.com

Background

The COVID-19 pandemic impacted around 168 million children worldwide; it led to the closure of schools for up to a year in nearly 200 countries between March 2020 and February 2021.

Though the short- and long-term health effects of school closure were apparent in children, it remains unclear whether school closures were needed.

Specifically in Ireland, they implemented many infection prevention and control (IPC) measures during the academic year 2020-2021 across all kinds of schools, which helped control SARS-CoV-2 transmission.

They covered five to 12-year-old, 13 to 18-year-old, and five-to-18-year-old children studying in primary, post-primary, and specialist schools, respectively, and all staff members at schools ≥20 years across 3,963 Irish schools. 

Notably, all studies assessing the SARS-CoV-2 spread observed its transmission was lower in schools than in the general population.

About the study

In the present study, researchers used the national COVID-19 case definition during the 2020–21 academic year; likewise, they defined an outbreak when RT-PCR confirmed cases occurred in two or more people, of which one had a confirmed diagnosis while the other had disease symptoms with evidence of in-school transmission. 

The Medical Officer of Health (MOH) of the regional public health department declared the occurrence of a SARS-CoV-2 outbreak in school and ensured documenting all related cases in the Computerised Infectious Disease Reporting (CIDR) system.

They also alerted the National Health Protection Surveillance Centre of Ireland. The agencies had standardized the management of COVID-19 outbreaks in these settings nationally. 

They referred all COVID-19 cases found to be infectious while attending school to the regional ‘Schools Teams’ for a public health risk assessment (PHRA), who assigned them a unique school identification number.

Once they identified an infectious case working in a school, including those with symptoms and even asymptomatic, these officials advised them to self-isolate for seven to 10 days, depending on the recommendations of the time. 

They also identified close contacts, i.e., people who had direct contact with a confirmed case through the PHRA process. They considered a person as close contact when they remained in contact for >15 minutes with a confirmed case in a school day while self-reporting their adherence to IPC measures, such as face masking. 

Once identified, they excluded these people from school for 14 days and provided them with appropriate public health advice and information regarding testing.

They also established COVID-19 testing pathways for students and staff on priority during 2020-2021. They considered all close contacts who tested SARS-CoV-2-positive as secondary cases. Close contacts could return to school only after testing RT-PCR-negative and turning asymptomatic. 

Ireland also had a national-level COVID-19 Contact Management Programme (CMP), a web-based information system, that assisted with contact tracing of all RT-PCR-confirmed COVID-19 cases.

Contact tracers used this system to contact people with confirmed COVID-19 to determine if they attended school during their infectious period and identify their close contacts. 

The team performed statistical analyses of all the available data on the national COVID-19 Contact Management Programme from week 19 of 2021. Note this data did not represent notified COVID-19 cases that underwent the data validation procedures through the CIDR System.

The researchers expressed categorical variables as percentages, estimating inter-group differences using chi-squared tests and considering p<0.05 statistically significant.

Results

Per the CIDR system data, 832 school outbreaks occurred between August 2020 and June 2021. It represented 3,655 cases, which covered index and secondary cases among school students and staff. Across 3,963 Irish schools, 44.7% reported at least one index COVID-19 case (in students or staff members) who attended school during the infectious period, and the PHRA process helped identify their close contacts. 

The study results revealed that school outbreaks in Ireland were generally small, with 34% of all these outbreaks comprising two and 92% comprising less than 10 cases. Strikingly, less than 3% of close contacts of COVID-19 cases in school settings tested positive. 

The authors noted 21,727 RT-PCR-confirmed COVID-19 cases among five-to-18-year-olds in Ireland during the three terms of the 2020–21 academic year. Only 2.4% of all five-to-18-year-olds in Ireland had COVID-19, constituting 18.2% of total COVID-19 cases notified in Ireland, i.e., 119,640.

Compared to people with COVID-19 between March 2020 and July 2021 across all age bands in Ireland, those aged five-to–18 years comprised only 13.3% of all cases. However, these case numbers among children aged five-to–18 years old increased over the three terms of the academic year 2020–21, from 15.5% of 58,148 cases in term one to 17.5% of 31,069 cases and 23.9% of 30,423 cases in term two & three, respectively. 

Across 1,771 schools in Ireland, testing occurred among 100,474 close contacts during the academic year 2020–21. It helped the researchers identify 2,373 secondary cases from schools, with an overall positivity rate equal to 2.4%. As expected, they observed the highest positivity rate in special schools, followed by primary and post-primary schools.

In one incident, public health officials found all staff members of 18 schools as close contacts and advised them to stop attending their respective schools. They also offered them free testing for SARS-CoV-2, as mandated.

It also helped them identify 90.5% (n = 90,953) of students and 9.5% (n = 9,521) of staff were close contacts. These results confirmed that students in primary and special schools had a markedly higher COVID-19 positivity rate than staff members (2.4% vs. 1.8%).

On the other hand, school staff members had a slightly higher COVID-19 positivity rate in post-primary schools (1.9% vs. 1.8%), but this variation was statistically insignificant (p = 0.88).

Conclusions

The current study favors international evidence demonstrating that educational facilities were a low-risk setting for SARS-CoV-2 transmission, given they implemented appropriate IPC measures and adhered to norms.

Thus, school closure must remain the last resort as a COVID-19 mitigation measure, and all children must be permitted to continue their education with minimum unnecessary disturbances.

In any future pandemic(s), schools should not be closed before carefully considering all the adverse effects and benefits of disrupting education. 

In the ongoing COVID-19 pandemic, the emphasis should be on the maximum uptake of COVID-19 vaccination among school staff and children for whom it is available, besides strict adherence to all SARS-CoV-2 mitigation measures in educational settings.

The ultimate goal should be maximum protection and uninterrupted education for all children.