The State’s public-health emergency team warned the Government that the Delta Covid-19 variant is set to cause a “significant” fourth wave of infection that could kill more than 2,000 people.
In a letter sent by the National Public Health Emergency Team (Nphet) to Minister for Health Stephen Donnelly, five separate modelling scenarios were presented for the coming months.
Under the most pessimistic scenario, there would be 681,900 cases by the end of September, while the most optimistic scenario would see 81,000 cases, the letter stated.
The most pessimistic scenario would see 12,985 hospital admissions in the same time period and 1,685 intensive care (ICU) admissions, as well as 2,170 deaths.
The most optimistic scenario would see 1,530 hospital admissions and 195 ICU admissions, as well as 165 deaths.
Nphet included what it called the “counterfactual scenario” where the Delta variant had not been introduced to the Republic. Had this happened a lower figure of 21,000 cases, 405 hospitalisations, 55 ICU admissions and 80 deaths was projected for the same period.
The letter from the chief medical officer Dr Tony Holohan said there had already been 47 confirmed Delta outbreaks associated with 80 confirmed cases, and 25 probable Delta outbreaks associated with 80 probable cases.
‘Very uncertain’
He said the profile of infection or severe Covid-19 disease requiring hospital or critical care over the coming weeks is “very uncertain.”
“What is clear is that the Delta variant, with its clear transmission advantage over the Alpha variant, is rapidly becoming the dominant strain, and in our partially-vaccinated population the increased risk of onward transmission associated with this variant makes a significant fourth wave of infection likely.”
The magnitude of that wave was uncertain, however.
The Nphet said the epidemiological situation in Ireland is “broadly stable in terms of disease incidence and numbers of cases in hospital and ICU, along with significantly lower mortality associated with Covid-19 compared to previous months”.
“However, this is set against a background of rapidly increasing prevalence in Ireland of the Delta variant which is significantly more transmissible and less susceptible to vaccines than previous variants. This poses a very substantial threat, particularly to those who are not yet fully protected though vaccination.”
In relation to the modelling, the Nphet said that in all scenarios the case counts rise very slowly during July. However, the “seeds of future growth are sown at this time, and case counts increase exponentially through August 2021 until a combination of vaccine-induced and infection-induced immunity slows growth through September and October 2021”.
The infections occur largely in the young, unvaccinated population, they said, but as the force of infection grows a significant number of infections also occur in older, vaccinated people.
Then at the later stage of the curve, cases among children may keep the numbers high.
“The latter part of the infection curve, beyond September 2021, is sustained by infection in children and adolescents, who are not currently eligible for vaccination. If children are less susceptible, and/or less likely to transmit infection, or a decision is made to vaccinate those under 16 years of age, the wave of infection will peak earlier and decline more rapidly.”
The Department of Health also on Tuesday evening confirmed that Dr Holohan’s letter to Government contained an error in a graphic depicting the various scenarios for the estimated number of Covid-19 cases over July, August and September.
The graphic said 165 deaths were projected under the most optimistic scenario. However, the correct estimated death toll in this scenario is 250 as referenced elsewhere in the letter.
