First two cases of new Covid-19 variant of concern confirmed in Ireland

On May 12, the European Centre for Disease Prevention and Control (ECDC) classified two sub-lineages of the Omicron variant of Covid-19 (BA.4 and BA.5) as variants of concern. 

First detected in South Africa at the start of this year, both started out as variants of interest, however, the ECDC – who regularly assesses new evidence on variants detected through epidemic intelligence, rules-based genomic variant screening, or other scientific sources – later reclassified them to variants of concern. 

Then, this month, the first two cases of the BA.4 variant arrived in Ireland with Chief Medical Officer, Dr Tony Holohan, confirming the news in his weekly letter to Minister for Health Stephen Donnelly. “In the context of the international situation in relation to these variants, it should be noted that, as of week 18 2022 (May 7), two cases of BA.4 and no cases of BA.5 have been identified in Ireland,” he wrote. 

“ECDC reports that BA.4 and BA.5 were first detected in South Africa in January and February 2022 respectively, and since then they have become the dominant variants there. ECDC has indicated that the currently observed growth advantage for BA.4 and BA.5 is likely due to their ability to evade immune protection induced by prior infection and/or vaccination, particularly if this has waned over time,” he continued. 

Noting that there is currently “no indication of any change in severity for BA.4/BA.5 compared to previous Omicron lineages”, Holohan stated that, with the exception of Portugal and Austria, the proportion of the two variants is still “very low” across EU/EEA countries. Omicron (BA.2) is still the dominant strain of Covid in Ireland. 

However, the ECDC has advised that, given the signals of increased growth rate, it is possible that one, or both, of these sub-lineages could lead to increased Covid-19 transmission in the future. Scientists also expect that BA.4 and BA.5 will eventually replace the BA.2 sub-lineage as the dominant strain in Europe. 

According to Holohan, “the overall epidemiological situation in Ireland currently provides a broadly positive outlook” but “we will need to continue to monitor developments with emerging variants over the coming weeks.” The letter, dated May 13, also says that the five-day rolling average of daily PCR-confirmed cases is 610 as of May 12, a 16% decrease from the 729 cases reported on May 5.

“Although there continues to be high levels of infection and a significant number of cases receiving general hospital care, the numbers of detected infections and hospitalised cases have reduced considerably over recent weeks,” he says.

The UK has also reported an increase in cases of the new variant, with approximately 115 cases of BA.4 and 80 cases of BA.5. 

As of May 10, approximately half of coronavirus-positive cases had been admitted to hospital for Covid-19, while the other half were asymptomatic infectious cases.