During a discussion on new measures being rolled out to halt the spread of the Omicron variant in schools, Calum Semple, Professor of Child Health and Outbreak Medicine at the University of Liverpool stressed it was vital that Britons “put to bed” the idea that COVID-19 is spread outdoors stressing it is indoors where the virus spreads.

       Speaking to Sky News, Professor Semple stressed: "First of all when you are outside there is ultra-violet light and there is good air change.

       "So you don't catch the virus outside... that has got to be put to bed."

       He went on to stress how the core issue of transmission remains inside the classroom where the air "may be stale" and allow the virus to linger.

       The Coronavirus expert noted how even some of the aerosols from people speaking can remain airborne "for a matter of hours if the air isn't changing".

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       He noted that facemasks, as well as proper ventilation, will prevent the virus from ripping through schools.

       The Government has sent out 7,000 air-cleaning units for classrooms up and down the country to keep circulation up to prevent transmission.

       It comes as Prime Minister Boris Johnson said he was "absolutely determined" to keep schools open in January despite record numbers of COVID-19 infections over the Christmas period.

       Facemasks have also been encouraged in secondary schools in England.

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       It comes as Geoff Barton, General Secretary of the Association of School and College Leaders, told Sky News that the soaring number of teacher shortages could mean supply teachers are not given enough time to be drafted in to cover those off sick, forcing school closures.

       He said: "The difficulty with the people I represent as school and college leaders is they won’t know until Tuesday morning, 8 o’clock…

       “When they start to get phones calls as to how many staff have tested positive and therefore will not be coming into school.”

       Paul Whiteman, General Secretary of the National Association of Head Teachers also warned that as many as "half" of teachers could be off work by Tuesday amid the rampant spread of Omicron.

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       He welcomed the Government’s plan to keep schools from closing but stressed getting resources into schools to prepare for high numbers of staff absences was vital.

       He told Sky News: “Everybody understands that keeping children in school is the best thing to do, so that has to remain the focus.”

       Most children will be back in the classroom by January 10.