Róisín Shortall (Dublin North West, Social Democrats)
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2762. To ask the Minister for Health if he will report on the NPHET forecast of the death rate from the delta variant per 1,000 cases of the virus in the most pessimistic scenario based on different levels of vaccination across the population; the basis for these forecasts; and if he will make a statement on the matter. [39055/21]

Stephen Donnelly (Wicklow, Fianna Fail)
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The modelling scenarios begin with some basic assumptions on the effective level of close social contact and the increased transmissibility of the delta variant. The level of close social contact is assumed to increase either to the level seen in early summer 2020 (moderate social contact) or late summer 2020 (higher social contact). The transmissibility of the delta variant is uncertain, so the scenarios use conservative estimates (where the delta variant is 1.97 times more transmissible than the variants circulating in 2020, based on estimates from ECDC) or higher estimates (where delta is 2.4 times more transmissible, based on published UK estimates of the relative transmission advantages of the alpha and delta variants).

This gives four scenarios for transmission, levels of infection and case numbers, ranging from optimistic (moderate social contact, conservative transmission advantage for delta) to pessimistic (higher social contact, higher transmission advantage for delta).

We know that the widespread administration of vaccines means that there will be fewer infections, and that infections are less likely to lead to severe disease, hospitalisation and mortality. The vaccination programme is incorporated into the model. Vaccine uptake ranges from over 95% in older and vulnerable cohorts to 80% in young adults. The models assume that the first dose of a vaccine is approximately 60% effective in preventing symptomatic infection with the alpha variant, and the second dose increases effectiveness in preventing symptomatic infection to 80-90%. Furthermore, one dose of vaccine is assumed to offer 70-85% protection against severe disease, hospitalisation and death due to infection with the alpha variant, with a second dose increasing vaccine effectiveness against severe disease to 90-95%.

Vaccines are known to be less effective in preventing symptomatic infection with delta, and this reduction in vaccine efficacy is taken into account in projecting the number of infections and cases in each scenario. However, the available evidence suggests that vaccines are equally effective in preventing severe disease with delta compared to alpha, and this is assumed to be the case in the models.

When all these factors are taken into account, on average per 1000 cases, the models project 15-25 hospitalisations, 2-3 admissions to ICU, and 2-4 deaths. These ratios are comparable to what is being seen in the UK and other jurisdictions.