Newer, more transmissible variants of Covid-19 now account for a majority of cases in Ireland, new data shows.
The BA.4 and BA.5 subvariants were responsible for more than 50 per cent of cases that were genomically sequenced last week, according to a report by the Health Protection Surveillance Centre.
Another new arrival, BA.2.12.1, which is a tweak on the BA.2 variant that has been dominant in Ireland since spring, accounted for a further 25 per cent of case that were sequenced. The remaining cases were BA.2.
All three variants developed from the Omicron lineage and are also spreading due to their ability to bypass immunity from past infection or vaccination. Many current cases are reinfections of people who had Omicron earlier this year.
BA2.12.1 has driven a surge of cases in the US but is now being displaced there by BA.4 and BA.5.
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It is likely the three variants are responsible for the current surge of cases in Ireland, where hospitalisations of Covid-19 patients have more than doubled in three weeks. The number of patients in hospital with Covid-19 on Thursday was 496, up 19 on the previous day. Of these patients, 25 are in ICU, down one. About half of hospitalised patients with the disease are there for other reasons.
According to the HPSC, 91 cases of BA.4 and 178 of BA.5 have been detected in Ireland through genomic sequencing. This bears little relation to the true number of cases as only a tiny proportion of cases is sequenced.
There is no indication the new subvariants are more lethal than previous ones, though data is limited.
A total of 24,992 infections with the Omicron variant have been recorded since November.
The HSE on Thursday again appealed to people eligible for Covid-19 boosters or vaccines to avail of them, citing the recent increase in cases.
Chief clinical officer Dr Colm Henry said the recent sharp increase in cases and hospitalisations may be attributable in part to emerging variants, which can evade immunity from natural infection with a previous variant or vaccination. “It is especially important that those who are 65 years or older, and those who are 12 years or older with a weak immune system who have yet to get their second booster vaccine, access the booster offered as soon as they can to ensure they are protected — particularly if we continue to see an increase in cases of Covid-19.”
Despite the rise in cases, the HSE is proceeding with plans to close all but 15 vaccination centres nationally. Vaccine doses are also available in many pharmacies and some GPs, it pointed out.
Hospital outbreaks
Outbreaks in hospitals rose threefold last week, while in residential institutions they doubled, according to the HPSC.
Overall, 53 new Covid-19 outbreaks were notified, 18 more than the previous week. There were 15 hospital outbreaks, compared with five the previous week. The number of outbreaks in residential institutions increased from eight to 16. Outbreak levels in other at-risk settings were generally stable.
A comparison of the death rate in nursing homes and community hospitals during the pandemic shows it has fallen from 24.2 per cent for over-65s in the first wave to 3.6 per cent in the fifth, most recent wave.
The number of positive tests increased last week, by 46 per cent for PCR tests and 55 per cent for antigen notifications. The rate of increase was highest among those aged 18-65.
Limerick, Clare and Louth recorded the highest rates of positive PCR tests, and Cavan, Leitrim and Monaghan the lowest.
Under current testing policy, most people with symptoms are not sent for a PCR test, so the figures for testing give a limited picture of disease trends.
However, in a clear indication of rising infection levels, almost a quarter of PCR tests last week were positive, the highest rate since April.
Separately, the HPSC said the number of cases of mystery hepatitis in children has risen to 14.
Meanwhile on Thursday the Bloomsday Banquet of the international James Joyce Symposium, due to have been held on Thursday night in UCD, was called off hours beforehand due to a surge in Covid-19 infections among participants.
The biennial symposium began on Monday at Trinity College and is being attended by about 300 scholars from all over the world.
