Blood tests in Ireland have begun to surface evidence of a weakening of defenses against Covid-19 in vaccinated people, with antibodies peaking in late January and falling since.
Antibodies are made by the immune system in response to the virus, either through vaccination or natural infection, to help the body fight off Covid in the future.
The first seroprevalence report, measuring antibodies in blood donors of all ages from October last year to June, showed that antibody levels for those who were vaccinated and had not contracted the virus had fallen since late January.
Mean total antibody levels in blood donors aged 20 to 69 years have plateaued or fallen since late January, but they started to rise in people aged 60 to 79 years in late April, likely due to a second booster dose.
The results come as booster vaccines are expected to be made available to a much wider population starting in the fall.
In the UK yesterday it was decided that everyone over the age of 50 is expected to be given a booster vaccine from September.
The Health Protection Surveillance Center (HPSC) seroprevalence report states that there is no antibody threshold that provides complete protection against infection, but higher antibody levels are “probably associated with a lower likelihood of infection.”
People also make antibodies after infection, and it found that 87 per cent of blood donors aged 20 to 29 were confirmed to have had the virus, “indicating high levels of community transmission”.
Meanwhile, 71 percent of people aged 30 to 49 and 60 percent of people aged 50 to 79 were infected.
Despite declining immunity, vaccination is still considered a good protection against serious diseases in younger healthy populations.
It comes amid growing signs the summer wave is slowing, with the number of patients in hospital with Covid falling to 943 yesterday, down from 1,055 on Monday.
Of those, 35 were in intensive care, down from 46 on Tuesday. The seven-day positivity rate is 35.5 percent, compared to 38.1 percent on Friday, July 8.
In her first weekly report on July 8, Acting Chief Medical Officer Dr. Breda Smyth that as of July 5, 554 patients were hospitalized directly due to complications from Covid-19.
Of these, 220 were over 80 years old; 182 were between 65 and 79 years old; and 83 were between 50 and 64 years old. One in 10 or 54 was between the ages of 15 and 49 and 15 were aged 14 or younger.
She said that of the 554, 43 percent had received a booster vaccine, 23 percent had their first vaccination course and a third were either partially or not vaccinated.
The proportion of patients in intensive care units directly resulting from a serious illness caused by Covid rose from 32 percent on June 28 to 38 percent on July 5.
Hospitals remained under pressure and 199 patients contracted the virus after admission in the week ended June 26, compared with 195 in the previous week and 187 in the seven days prior.
dr Smyth said at midnight on July 5 there were fewer than five Covid-related deaths in July, with 61 in June, 119 in May and 340 in April.
dr Smyth said that on July 6, 53 percent of people age 85 and older; 58% of 75-84 year olds; and 48 percent of people aged 65 to 74 had taken the second booster shot, a rate that was “suboptimal,” she warned.
While the overall number of infections and hospitalizations has worsened, there are signs of the current wave slowing down, she added.
The BA.5 form of Omicron dominates here.
Evidence of the knock-on effect of hospitals coping with a surge in Covid-19 patients was shown yesterday in June waiting list figures.
The number of patients requiring surgery in June rose to 80,275 from 79,690 in May, according to the National Treatment Purchase Fund.
It highlights the setbacks hospitals are facing due to the disruption caused by Covid-19 cases and high emergency room attendance.
70 patients were waiting for a bed at Galway University Hospital yesterday, the highest number since 2019, nurses have warned.
https://www.independent.ie/irish-news/health/tests-reveal-that-defences-from-covid-jab-fell-from-late-january-41844105.html Tests show defenses against Covid surge have fallen from late January