Almost 40 per cent of young schoolchildren had already been infected with Covid-19 by last January, as the Omicron wave of the virus was getting under way, a new study shows.
Three out of every 100 preschoolers had also had an infection by this time, the first round of results from the National Serosurveillance Programme indicate.
Almost all adults had antibodies to Covid-19 by last February, thanks to vaccination or previous infection, though levels declined among older people, the study also shows.
The study gives an indication of the high levels of vaccine or infection-induced protection in the population at the start of the year, even before large numbers of people were infected in spring as the Omicron wave surged.
Latest figures point to a fresh wave of cases, with test positivity rising for more than a week and further increases in the number of people with Covid-19 in hospital.
There were 256 patients in hospital with the virus on Monday morning, up from 232 the previous day. This represents a 53 per cent jump on the 167 hospitalised Covid-19 patients recorded on May 28th, the lowest figure this year.
The reasons for the new rise in hospitalisations are not entirely clear, though they follow a rise in activity in society, with socialisation and travel approaching pre-pandemic levels.
New subvariants of Omicron, which transmit more readily, could also be a factor; while very few cases of BA.4 and BA.5 have been detected here, only a tiny percentage of cases are being genomically sequenced so the exact variant involved can be identified.
The number of Covid-19 patients in intensive care increased again on Monday to 23, from 21 the previous day.
Writing in The Irish Times, immunologists Prof Kingston Mills and Prof Cliona Farrelly say Ireland needs a preparedness plan for the next pandemic, built on a solid foundation of scientific evidence and research.
“We need the best clinicians and scientists, including infectious disease experts, immunologists, virologists, epidemiologists, engineers and computational scientists working together in a national research centre focused on pandemic preparedness.
“This would allow rapid introduction of effective surveillance systems, diagnostic assays and modelling to map the spread of the microbe and would also contribute to the global research effort in the rapid development of drugs, vaccines, and other approaches to control the infection.
“The only certainty is that other microbes will transmit from animal to humans or evolve to become more transmissible or to evade antimicrobial drugs or vaccines,” the two scientists write. “So, we need to be better prepared to deal with the next microbe that has the potential to cause an infectious disease pandemic.”
In the study published by the Health Protection Surveillance Centre, 170 children aged between one and 12 were tested last December and January. At this stage, vaccination of five to 12-year-olds had just been approved but the rollout had not yet begun.
Antibodies to Covid were found in 38.4 per cent of the children. For those aged one to four, the seroprevalence figure was 28.8 per cent.
Antibodies to Covid-19 were found in 43.5 per cent of children aged five to 12; and for the vast majority (37.9 per cent) this was due to previous infection.
Testing of 1,410 adults for the study took place in January and February. Overall seroprevalence was 96.5 per cent, rising to 100 per cent for those in their 70s, indicating nearly all the population was either vaccinated or had been previously infected.
Levels of antibodies peaked at age 55 and declined in people aged 60 and over.
Analysis showed 34.5 per cent of people had been previously infected, but this varied by age, from 51 per cent for the 18-29 age group to 13.8 per cent for those aged 70-79.
