Flu activity on the rise and four outbreaks but still at low level

The rate of GP consultations for flu in week 50 (December 12-18) was 9.4 per 100,000 of the population.

This was higher than week 49 (6 per 100,000) and the same period in 2021/22 (1.7 per 100,000), when, due to COVID-19 restrictions, flu activity was historically low.

Activity remains below the baseline threshold (11.3 per 100,000), which is a rate calculated using the Moving Epidemic Method (MEM), which is based on the last ten flu seasons.

Once the baseline has been breached – which it hasn’t been yet – the following increments are followed: low activity (11.3 to 21.8 consultations per 100,000); moderate activity (21.8 to 57); high activity (57 to 87.1); and very high activity (over 87.1 consultations).

Last week flu consultation rates were highest among 15 to 44 year olds at 14.6 per 100,000. Rates were higher in all age groups compared to 2021/22.

The rate of flu consultations at Primary Care Out-of-Hours (OOH) Centres was 4.9 per 100,000 population in week 50.

This was lower than week 49 (6.2 per 100,000) but higher than the same period in 2021/22 (3.1 per 100,000).

The bulletin shows the highest rates were for very young children perhaps reflecting concerns over the increase in Group A Streptococcus infections this winter which have claimed a number of lives in Ireland and Britain.

The rate of OOH consultations was highest in those aged 0-4 years in week 50 (7.3 per 100,000 population).

Rates were higher in all age categories with the exception of the 45-64 year old age group.

Notwithstanding the below-threshold rates at both GP and OOH centres there were still four outbreaks of flu over the week December 12-18.

These were all outbreaks of Flu A (untyped) with three in a hospital setting and one in a care home.

There have been a total of 11 influenza outbreaks (two in a care home and nine in a hospital) and one Respiratory syncytial virus (RSV) – a common cold or flu-like virus – outbreak in a care home, this season.

The number of respiratory-associated deaths was marginally lower than during the same period last year.

"In week 50, 84 respiratory associated deaths out of 360 all-cause deaths were reported (23%). This is slightly lower than the same period in 2021/22 (87 respiratory deaths out of 363 all-cause deaths, 24%),” the bulletin states.

These deaths included deaths where bronchiolitis, bronchitis, influenza or pneumonia were mentioned on the death certificate.

Thus far our flu season has not been as bad as initially feared. When Australia experienced its worst flu in five years, a similar outcome was expected here due to predictable global circulation patterns.

The latest bulletin from the PHA show H1N1 - the virus identified in Mexico in 2009 which was responsible for the global 'swine flu' outbreak of that year - is still accounting for the largest number of hospital cases with confirmed influenza across the north.

In week 50, 235 samples were positive for flu (108 Flu A(H1N1), 74 Flu A(untyped), 51 Flu A(H3) and two Flu B from 1726 samples submitted for testing in laboratories across the north.

Flu activity in the north very low this winter