Public health expert explains science behind safe return of schools
Professor Philip Nolan, Chair of the Chair of NPHET Irish Epidemiological Modelling Advisory Group, has said that adults "starving" Covid-19 of opportunities to transmit is what allows schools to be safe.
While case numbers have continued to rise in the Republic of Ireland, and regional restrictions placed on three counties in recent weeks as a result, concerned parents and students have understandably questioned the logic of restricting visits to households while allowing students and staff return to schools.
Professor Nolan explains that the adult population as a whole reducing their contacts and preventing the spread of the virus in the community is what will allow schools to safely return;
"We have about 5 million people in the country. If each of us had, as we would have this time last year, say 10 close contacts per day, that’s 25 million opportunities per day for the virus to transmit
"About one million of the population are of school-going age. If the other 4 million reduce their close contacts to, say, just 2 per day, we are down to 9 million close contacts per day. We have reduced the opportunities for the virus to transmit by more than 60%."
Professor Nolan also explains that basic public health advice being employed both in schools and in the community continues to decrease that risk substantially;
"If we also reduce the risk that our close contacts might lead to transmission (physical distancing, hand/respiratory hygiene face coverings where appropriate) even if these measures only reduce the risk by half then we have reduced the risk of transmission by about 80%."
Professor Nolan also said that if the basic reproduction number (R number) of the virus is between 3 and 5, then this 80% reduction in transmission will be enough to bring R below 1, and the number of infections will decline.
Ireland's current R number is estimated to be at 1.2.
He concluded by summarising that adults outside schools play a hugely important role in keeping schools safe for students, and the community as a whole;
"Simply put, if older adults starve the virus of opportunities to transmit (limiting our contacts and being careful) the young can have the higher numbers of contacts that classroom education requires; the sum total of all contacts for the population level remains low.
"The risk is even lower if (i) the level of disease in the community is minimised (ii) appropriate precautions are taken in schools. We can all contribute to the first, and teachers and principals have done extraordinary work to make schools as safe as possible."
You can read the explanation in full below.
If we can only have 6 people in our houses, how can we have 30 children in a classroom? It’s a reasonable question. But it’s not a contradiction; in fact, these measures are connected and coherent. The following explanation is a simplification, but illustrates the principle. 1/8 pic.twitter.com/tSrWVyjodf
— Professor Philip Nolan (@President_MU) August 21, 2020