Professor Philip Nolan:

Incidence in those aged 19 to 24 years has effectively collapsed as vaccinations have become effective. We have gone from 100 cases per 100,000 people per day in early August in that age group to below 40 cases. There has been a 60% reduction in the incidence in the university going cohort. That is allied with mitigation measures that universities have put in place around reducing crowding, mask wearing in the vast majority of indoor settings and the installation of CO2 monitors to ensure adequate ventilation. We have modelled scenarios where things might go wrong. Based on what we have seen over the last period of time, we would not expect a significant wave of disease as that group of students returns to third level. The situation will have to be monitored.

To broaden the discussion, last year when we opened schools the demand for testing tripled and the incidence went up about 50%. In the past two weeks as we have opened schools again from a higher base demand for testing has tripled. We are now testing close to 1% of the primary school going age cohort every day. That is good and prudent. It means that if there is any resurgence or surge in disease in that age cohort we will see that. The threefold increase in testing is again translating into about a 50% increase in detection. There may have been infections that were out there during the summer. In other words, we may now be detecting cases the equivalents of which, with lower testing during the summer, we were not detecting in July and August.

I want to make a final point on mitigation measures in third level and schools. There is a great deal of discussion about the balance between ventilation, mask wearing, hand hygiene and so on. It is really important to state that even though people may say they think aerosol transmission is more important than other modes of transition and, therefore, ventilation is as or more important, we simply do not have the evidence to back that up. We know that the virus is transmitted by some mix of direct contact, short range droplet and aerosol transmission where we are close to each other and literally spraying those droplets at each other, long range aerosol transmission and surfaces. Even though we know surfaces probably do not matter much, we simply do not know the balance between the others. Our public health doctors tell us it is usually close contact.

It is very important that in the public health messaging we get the balance right. Hand and respiratory hygiene, physical distancing and mask wearing and ventilation remain important, but there is no way of knowing which of those is more important so we need to-----