Increased circulation of COVID-19 due to spread of BA.4 and BA.5 Omicron sublineages


Since the end of May, signals across several COVID-19 and respiratory illness surveillance systems have indicated an increase in COVID-19 circulation. Data from week 24 (between June 12 and June 18 2022) indicate an ongoing increase:

  • In week 24
    • 10,435 new confirmed COVID-19 cases were reported on the Computerised Infectious Disease Reporting system (CIDR). This is an increase of 52.6% compared to week 23 when there were 6,837 confirmed COVID-19 cases notified.
    • 34,581 SARS-CoV-2 tests were performed, of which 10,224 (29.6%) were positive. This is an increase compared to week 23, when 24.5% were positive.
    • 13,059 positive antigen test results were registered on the HSE Positive Antigen Portal. This is an increase of 48.3% reported results compared to week 23 when 8,808 cases were registered
      o 79 COVID-19 outbreaks were reported in healthcare or residential settings compared to 53 in week 23.
  • As of the 21st June 2022, the 14-day incidence rate of confirmed COVID-19 cases was 393.9/100.000, this was a 36% increase compared to the rate on 14th June 2022 (290.5/100,000)
  • Data from the HSE Performance Management Improvement Unit (PMIU) COVID-19 system showed that at 8am on Wednesday 22nd June, there were 629 patients in acute hospitals that had COVID-19 infection. This an increase of 32% compared to Wednesday 15th June when there were 477 patients.

To date, there is no indication of an increase in ICU admissions associated with the current upsurge. Patients in ICU with COVID-19 did increase slightly from a low for 2022 of 18 patients on 29th May, but have been stable with between 20 and 28 patients a day since 6th June.

There is also no indicator of increased mortality, however, there can be a time-lag in the reporting of deaths on CIDR.

The current increased circulation of COVID-19 is due to the spread of the BA.4 and BA.5 Omicron sublineages, which are replacing the previous dominant Omicron variant BA.2. Laboratory results indicated that in week 24, 77% of specimens were likely to be BA.4/BA.5 based on PCR screening.

Similar increasing trends are being seen in several other countries across Europe as BA.4 and BA.5 become the dominant variants in circulation. This is likely due to their ability to evade immune protection caused by prior infection and/or vaccination, particularly if this immunity has waned over time. There is currently no indication of any change in infection severity compared to previous Omicron lineages. In addition, currently licensed COVID-19 vaccines confer high levels of protection against severe disease outcomes for all variants, including Omicron with a booster dose. However, as in previous waves, if COVID-19 case numbers increase substantially, some level of increased hospital and ICU admissions is likely to follow.

People should remain vigilant and follow public health advice on preventing the spread of COVID-19.

If you have any symptoms of COVID-19, even mild ones, you should self-isolate (stay in your room) until 48 hours after your symptoms are mostly or fully gone, regardless of the result of an antigen test. Certain groups of people with symptoms should get a COVID-19 test.

Completing your COVID-19 vaccination, including booster doses, will reduce the risk of getting severely ill from COVID-19.

For advice on preventing the spread of COVID-19 and what to do if you have symptoms go to: 

For information on COVID-19 vaccination, including how to get the vaccine, go to: