I think most people actually *do* understand the principle, expressed accurately here by @President_MU. The problem is that they don't accept the various implicit assumptions. 1/15 https://twitter.com/President_MU/status/1296760361228673027

First assumption is that 4 million people will play ball with whatever guidelines are announced. They simply won't. Clearly many of our own civic leaders are unable/unwilling to do so #golfgate 2/15

Such models work well with smaller localised outbreaks, where our evidence-base is drawn from these. COVID19 is different. It is a truly global pandemic & co-operation of 4 million people in Ireland after 6 mo of lockdown is a lot to expect. Too much to rely on. 3/15

So while house visits are limited to 6, average social contacts will be much higher in reality. Adherence research suggests that people will always find a way to rationalise rule-breaking ( #golfgate again) 4/15

Second assumption is that national risk equates to individual consequence, i.e. we can afford for some school-age children to get this virus so long as the national numbers stay low. 5/15

This presupposes no long-term sequelae, and ignores onward transmission. If a 10yo attends school on re-opening day, should they hug their grannies when they come home that evening? Should they hug their parents? 6/15

Each potential recipient of the virus faces the same consequence should they get it, whether or not risk is low. 7/15

Third assumption is that school-age children can afford to get this virus. This assumes no long-term sequelae and plays down onward transmission (to granny etc.). 8/15

In my view, this is the biggest social challenge we face. We need to get people to understand transmissability. You might be okay, but your contacts might not be so lucky. The kids might be fine, but granny might end up dead. 9/15

Or the kids might end up with long-term health problems. We don't really know. We thought first that adults who recover would be fine, but turns out that's not the case. Evidence on all this is limited, not least because most schools globally have been shut during pandemic. 10/15

Fourth assumption is that this combination (6 per house visit, 30 per classroom) is the only option. It's not. 11/15

For example, risk would be much lower with 6 per house & 10 per classroom. I'm not saying this is practicable, just that it's lower-risk. My point is that 6/house-30/classroom argument is arbitrarily framed. 12/15

I agree that schools and principals have been working extraordinarily hard prepping to re-open. Logistically we need to find a way to provide social & educational benefit of schooling. All this is important. 13/15

But we shouldn't justify risk-taking in schools by pointing to lower risk-taking nationally (especially if we can't deliver the latter). We should follow models e.g. Denmark where re-opening is staggered, pods small, & parents who can home-school are encouraged to do so. 14/15

I am a strong proponent of science-based public policy and evidence-based intervention. But we need policies that will convincingly pay off in practice & minimise (rather than reduce) harm, not just make statistical sense on the back of an envelope. 15/15