Covid-19 wave ‘at or beyond’ halfway point, says HSE’s chief clinician

State in third or fourth week of six-week summer wave if Ireland tracks Portugal’s infection rate

Ireland is at or just past half-way through a six-week Covid-19 wave if trends follow Portugal’s recent experience, HSE chief clinical officer Dr Colm Henry has said.

New subvariants of the Omicron strain, the BA4 and BA5 variants, are being blamed for the summer surge of infections as the virus causes disruption to health services and travel.

Dr Henry said the wave of infections in Portugal lasted for four to six weeks before declining. “If you are an optimistic, you would lean into the Portuguese trends. If so, we are probably in week three or four,” he told The Irish Times.

Dr Henry said the slower increase in the number of Covid-19 hospitalisations compared with the last wave in March was a positive sign, but he expressed concern at an increase in infections during the summer with hospitals experiencing pressures “akin to the levels of January” in July.

“The hope would be that this shallower incline is maybe a sign that things are beginning to level off and then fall,” he said.

“To me, it is still troubling that in the middle of something that we always hoped would become a seasonal virus is a virus that can appear in any season.”

He said the new subvariants had a “significant growth advantage” and anyone infected by the Delta last summer or autumn or the early Omicron strain last winter could now be reinfected.

“You would have little or no immunity from infection but protection from vaccine in terms of preventing serious illness is probably long lasting,” said Dr Henry.

The number of people in hospital with Covid-19 rose by a further 14 in 24 hours to 812 on Friday, up from the 697 a week earlier and from 167 at the end of May, the most recent low.

The number of people in hospital intensive care units with Covid-19 fell by one to 32.

Christine Loscher, professor of immunology at Dublin City University, said this wave should peak in the next week or two, tracking Portugal’s experience. Covid-19 hospitalisations and the positivity rate were still rising, indicating that the wave has yet to peak, she said.

“We are probably about four weeks into our climb and we are nearly at the stage where it will start to plateau in the next week or two,” she said.

The seven-day positivity rate - the number of people testing positive out of the overall number of official PCR tests carried out - has risen to 36 per cent, an increase from 27 per cent in mid-June.

Prof Loscher estimated that new daily infections were “probably well over 10,000″ given that people were not logging positive antigen test results.

Paul Moynagh, professor of immunology at Maynooth University said the State was “maybe halfway through” a four- to six-week wave, similar to Portugal’s experience.

“We seem to be into this pattern of periodic waves that come every four months. It is not surprising. After a wave of infection, we make antibodies but those wane over the four-month period,” he said. “We should probably plan for the worst-case scenario that there will be a wave in winter and that may even be higher in winter than in summer.”

Meanwhile, new Central Statistics Office data show that Rathfarnham, Terenure and Dundrum in south Dublin had the highest rates of Covid-19 first boosters, at 74 per cent of the eligible population, while Buncrana in Co Donegal had the lowest rate at 35 per cent.

The highest rate of fully vaccinated 5- to 11-year-olds was also in south Dublin, in Stillorgan, Dún Laoghaire and Rathdown, at 53 per cent, while Buncrana had the lowest rate at 4 per cent.

Simon Carswell

Simon Carswell

Simon Carswell is The Irish Times’s Public Affairs Editor and former Washington correspondent