SARSCoV2 Delta And Omicron Transmission Within Educational Settings In Relation To Communitybased Outbreaks And Mitigation Measures

In a recent study published in Preprints with The Lancet *, researchers assessed whether school closures during the coronavirus disease 2019 (COVID-19) outbreak prevented transmission of the virus in Australia. In particular, they focused on early childhood education and care (ECEC) schools and sites in New South Wales (NSW).

Researchers have filled a knowledge gap in the transmission dynamics of acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during a period corresponding to two outbreaks of COVID-19 caused by the worrisome variant of SARS-CoV-2. (VOC), Delta and Omicron.

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School closures during the unprecedented COVID-19 pandemic have had a devastating impact on the lives of millions of children around the world. This impact is worse for young children, especially those with learning difficulties and those from lower socio-economic groups. The research also documents the huge impact on many children's mental health due to prolonged social isolation.

Most children have mild or no symptoms of COVID-19; therefore, they do not appear to be the cause of community transmission of SARS-CoV-2. However, few studies attempt to provide empirical evidence in favor of not closing schools.

About the study

In the present prospective observational cohort study, the researchers assessed the transmission of SARS-CoV-2 in an educational setting from infected case to contact during the circulation of VOCs from Delta and Omicron in Australia. They grouped their results by type and vaccination status of participating students and staff. In addition, they compared their findings to community-level incidence rates of COVID-19 and reported findings of severe disease.

In this study, 1,349 and 440 students and staff from 1,187 schools and 300 preschools attended their institutions while infected. The team estimated the secondary attack rates (SAR) of these children and adults infected with SARS-CoV-2 between June 16 and September 18, 2021, and October 18 and December 18, 2021. They compared SAR data estimated between states. – data on indicators, their availability and vaccination status. They then looked at 24,279 of their contacts and tested 93.2% of them for COVID-19 to identify secondary cases.

the results of the study

The observed SAR for 312 schools and 139 PAUDs was 3.5% and 5.6%, respectively. The overall SAR during both study periods was four times higher than when the ancestral strain was dominant (4% vs. 1.2%). Unvaccinated personnel are at higher risk of developing secondary cases. Also of note, DAS were comparable for Delta and Omicron periods (4.6% and 5%) in unvaccinated participants, but higher than vaccinated close contacts at 1.3% and 2.2%.

Researchers have observed an increase in the frequency of school attacks since the introduction of Omicron in late 2022. Similarly, an increase in school attendance has increased the number of cases and secondary cases. This has not affected community transmission, although the Australian government has eased public health measures, which at the same time limit community mixing. Amazingly, at the same time, on 30 October 2021, 60% of 12-15 year olds in NSW received their primary series.

Given the high vaccination rates, even with the advent of Omicron, the rate of case-to-contact transmission in well-vaccinated 12-year-olds did not increase significantly compared to delta-VOC transmission. Therefore, the authors could compare the risk of COVID-19 infection among schoolchildren based on vaccination status and close contacts exposed to SARS-CoV-2 VOCs.

Because the volatile organic compounds of Omicron have a greater potential to evade vaccine-induced immunity, the rate of infection with Omicron in children and school personnel after close contact with a sick person is higher, although comparable between vaccinated and unvaccinated people. However, vaccines, especially boosters, protect infected children and staff from serious illness.

As a result, although there were several outbreaks in NSW following Omicron and frequent testing identified outbreaks, this did not lead to long-term school closures. In general, SAR in schools and kindergartens remained significantly lower than in homes and public places, even after the introduction of Omicron.

The researchers also noted that staff had more primary and secondary cases of COVID-19 than children. However, this is probably due to the fact that they work closely with other students and staff, especially in special schools. Fortunately, hospitalization rates during Delta and Omicron transmission among children and staff infected with SARS-CoV-2 remain low. Most hospitalizations occurred in unvaccinated workers (56.2%) and not in children. Most children have mild illness, and even young infected children who have not been vaccinated do not appear to be at increased risk of developing a severe form of COVID-19.

cONcluSiON

The current study results support keeping schools open and teaching offline, as school closures are not associated with high levels of community transmission of SARS-CoV-2 in Nova Scotia, South Wales. More importantly, these data can form the basis of future vaccination policy in Australia.

Furthermore, the findings underscore the importance of prioritizing vaccination against COVID-19 for school personnel and confirm that children, even when in school, are not community-level carriers of SARS-CoV-2. There is also an urgent need for stronger monitoring systems and evidence-based decision-making to safely and sustainably deliver offline learning during the current COVID-19 pandemic.

*Important note

Lancet preprints publish preliminary scientific reports that have not been peer-reviewed and, as such, should not be considered definitive, guide clinical or behavioral health practice, or be considered established information.

According to the WHO, the new variant Covid XBB.1.5 is the most contagious subvariant ever found.