‘Small number’ of Omicron sublines detected in the state

There have been a “small number” of cases of a subline of the Omicron variant detected in the state, a public health official said.

However, Cillian De Gascun, director of the National Virus Reference Laboratory, said there were indications that the presence of BA.2 could be increasing.

According to the World Health Organization (WHO), the Omicron variant has three main sublines: BA.1, BA.2 and BA.3.

BA.1 was largely responsible for the spike in Omicron cases over the winter period, according to the WHO, leading to a record number of cases detected in many countries.

However, the prevalence of the BA.2 sublineage has increased internationally in recent weeks. It has already become dominant in Denmark and is expected to become dominant in the UK in the coming weeks.

The UK Health Safety Agency has declared the subline an “investigational variant”, with early analyzes suggesting it has a growth advantage over BA.1.


There are currently no data on the severity of BA.2 versus BA.1, and a preliminary assessment by UK officials found no difference in vaccine efficacy against symptomatic disease between the two.

In response to questions from The Irish Times, Mr De Gascun said the UK risk assessment “does not give too much cause for alarm at this stage”.

The difference in mutations between the two subtypes allows officials to monitor the emergence of BA.1 through genome sequencing, he added.

BA.1 can be detected by S gene target failure PCR assays [SGTF]while BA.2 differs because the S gene is detectable.

“So, although we have only seen a small number of BA.2 cases in our sequencing to date, the proportion of SGTFs has increased from 97% to 93% in the past few days, which could signal the start of something, which we will of course continue to monitor,” said de Gascun.

Genome sequencing

According to figures from the Health Protection Surveillance Center (HPSC), some 2,936 cases of Covid-19 in Ireland were identified as the Omicron variant through genome sequencing between November 25 and January 17.

Of these, 2,926 were BA.1, nine were BA.2 and one was BA.3.

The WHO said investigation of BA.2 characteristics, including virulence, should be “prioritized independently (and comparatively) to BA.1”.

Meanwhile, the National Public Health Emergency Team (Nphet) reported an additional 5,109 PCR-confirmed cases of Covid-19 on Friday.

Additionally, 4,482 people registered a positive antigen test through the HSE portal on Thursday.

At 8 a.m. on Friday, 707 Covid-19 patients were hospitalized, including 69 in intensive care.

The Health Ministry said it would no longer report daily case counts on weekends. Covid cases reported on Monday will reflect weekend figures, he added.

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