Dr Cillian de Gascun has said there are three main issues that NPHET are considering with regards to the Delta variant; transmissibility, infection severity and its impact on pre-existing immunity (reinfection risk) and vaccine effectiveness.
The NPHET member has also confirmed that the Delta variant appears to be between 40% and 60% more transmissible than the Alpha variant, which has been dominant in Ireland for the last five months.
In terms of its epidemiological structure, the Delta variant has an increased growth rate and secondary attack rate, increased household transmission and laboratory evidence of increased replication in biological systems that model the human airway.
Dr de Gascun also said that "Delta is almost certainly at least twice as transmissible as the virus we experienced last summer" and that based on data from Scotland and England, the Delta variant has an increased risk of hospitalisation among infected individuals.
In a post online, the doctor said: "However, we do see a reduction in vaccine effectiveness (VE) for Delta compared with Alpha against symptomatic infection, particularly after one dose. Although this is concerning, VE against Delta is high after two doses, and VE against hospitalisation is maintained.
"In the UK, Delta is the dominant variant, accounting for approximately 97% of cases. As a consequence, case numbers, hospitalisations, and deaths have increased in recent weeks. ECDC also predicts that Delta will be responsible for 90% of EU/EEA infections by the end of August."
The statement adds that Delta will likely be dominant in Ireland sooner than August.
He adds: "This dramatic increase in the proportion of Delta over the last two weeks will almost certainly lead to Delta dominance by the middle of July, with a consequent increase in case numbers, hospitalisations, and mortality in the following weeks
However, in contrast to last summer, we now have very effective vaccines. The key is to protect each other through established public health interventions (hand hygiene, distancing, mask-wearing, managing number of contacts) while the vaccines take effect."
