Economy 15 February 2024, 11:29am

Flu season still on an upward trajectory in Hungary

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More people with influenza infection were hospitalised in Hungary on the 6th week of 2024 than a year earlier, while there were fewer hospitalisations due to Covid and RSV. More than a third of those in hospital with severe acute respiratory infection (SARI) are children aged 2 and younger, and more than 82% of RSV patients belong to this age group. Half of those seeking medical help with SARI were aged 0-14 (over 147,000) and 40% of those showing flu-like symptoms were also in this age group. More than three quarters of those in hospital with COVID-19 were aged 60 and older.

The flu season generally peaks between the 7th and 10th week of the year, but the highest figures can vary greatly from one year to another. The coronavirus pandemic, for instance, put a serious dent into the spread of the flu (see graph below).

The number of people seeking medical help with influenza-like symptoms per 100,000 population (610.6) was higher than currently four times in the past 12 cold seasons (in 2014/15, 2016/17, 2017/18, and 2018/19).

For the 52nd week of 2023, the NNK published only a couple of figures, hence the gaps in the graphs. The timeline on the second graph goes up only to the 6th week for a closer look. The epidemiological curve remains on an upward trajectory but it is not a rare occurrence in this time of year.

On the 6th week of 2024, a total of 293,200 people sought medical help with severe acute respiratory infection (SARI), of whom 59,200 (20.2%) had flu-like symptoms. The former figure marks a 8.2% increase and the latter a 24.9% jump growth over the 5th week.

We can also compare the SARI and flu numbers for 100,000 inhabitants. The epidemic has been more severe in 2023/24 than in 2022/23, apart from a few weeks.

We need to highlight that this year authorities perform more tests than a year ago, even though the number of samples tested remains extremely low (397 in total on a national level last week, almost exactly as many as a week ago, 398). The early zeal has abated by now, though. While initially six, eight, and even ten times more samples were tested, the multiplier is now just around two (in terms of the cumulated number of tests that is).

The COVID-19 positivity rate dropped further to 3.8%, while the influenza positivity rate climbed higher to 42.6% from 32.4% on the 5th week. The positivity rate for the respiratory syncytial virus (RSV) rose further to 7.8% from 6.0% on the preceding two weeks.

If we take a look at the positivity rates on the individual weeks, we find that there was a turnaround on the 2nd week, with the influenza positivity rate (14.0%) higher than the Covid positivity rate (13.6%) for the first time in the current flu season. As noted above, the gap has widened considerably since then.

If you're wondering how the weekly positivity rates might turn out, here's how it went down last year, not that it is any guarantee that it will be repeated, but still:

As regards all samples tested up to the 6th week, the Covid positivity rate continues to stand out, but the flu positivity rate is coming up fast and will be higher in just a few weeks.

The share of coronavirus in all samples tested (orange lines) was about half than currently a year ago (12.7% vs. 23.4% currently), while the percentage of influenza in the samples (green lines) is way lower now than in the sixth week of 2023 (12.3% vs. 26.6%).

As regards the prevalence of respiratory syncytial virus (RSV) in the samples (blue lines), the situation is much better in the current cold season than in 2022/23, with the share only at 2.5% on the sixth week this year versus 10.5% a year ago. Note that these are the percentages of the select pathogens found in all samples tested up to the 6th week.

People tested positive for influenza and RSV had to be hospitalised for the tenth consecutive week in this flu season. The 47th week was the first one when one of the samples showed influenza infection (up at 547 in total by the end of the 5th week). Other pathogens identified between the 40th and 6th week were SARS-CoV-2 (1,036), respiratory syncytial virus (RSV, 111), adenovirus (3), parainfluenza (5), human metapneumovirus (HMPV, 29, and rhinovirus (38).

THERE WERE 343 PEOPLE IN HOSPITAL WITH SARI ON THE 6TH WEEK, VERSUS 291 A WEEK AGO. 7.6% OF THEM WERE TREATED WITH COVID-19, down sharply FROM 20.3% A WEEK EARLIER, WHILE almost a third OF THEM (30.6%) WERE TREATED WITH INFLUENZA, UP FROM 25.3% ON THE 4TH WEEK, and the share of rsv patients edged up to 18.1% from 15.1%.

The graphs below show a comparison with the previous 'flu season'. In 2022/23, there were no reports of people with Covid in hospitals, but that doesn't mean there weren't any (there were 100 on the first week of 2023, so it's a pretty safe bet that not all of them got to that stage overnight).

The second chart depicts the number and share of people infected by influenza virus in hospitals. As you can see (orange columns, light blue curve), this 'flu season' is much worse in this respect than the previous one. The chart starts on the 49th week because that was the first week in this season when someone infected with influenza virus had to be hospitalised.

We have the same graph for respiratory syncytial virus (RSV), which shows that this infection was more severe in the previous 'flu season', although both the number of RSV infections and related hospitalisations did pick up on the sixth week of 2024.

Another important indicator of the severity of an epidemic is how many of those hospitalised end up in the intensive care unit.

As mentioned above, there were 343 people with SARI in hospital on the week under review, up from 291 a week earlier. 43 of them were in the ICU, which corresponds to a 12.5% ratio, which figures compare with 35 (12.0%) a week earlier.

35.9% of those hospitalised with SARI were children aged 2 years or younger (up from 30.2% a week ago), while 33.5% of them were aged 60 and over (down from 39.5% on the 5th week). For the first time in this flu season, both the number and share of children aged 2 years or younger in hospital with SARI came in higher than the corresponding figures for those 60 and over.

The COVID-19 vaccination coverage of Hungarians aged 60 and older is dramatically low even by European standards, the latest update by the European Centre for Disease Prevention and Control (ECDC) shows.

Half of those with SARI are children

Finally, we have an age breakdown both for SARI and flu patients. Children up to the age of 14 are on top of the SARI age rankings in terms of numbers, and for the fourth time this season they are also on top in the flu rankings, while the second hardest-hit cluster is the 15-34 age group. The right-hand charts show the share of people with SARI and flu-like symptoms by age group.

Looking back on the 2022/23 data we find that the 0-14 age group was the hardest hit throughout the flu season in terms of SARI, while in terms of flu-like symptoms they were the most affected age group between the 3rd and the 15th week of this year, i.e. from mid-January to mid-April.

On the 6th week this year, more than 147,000 children sought medical help with SARI, half of all people that turned to the doctor with some respiratory infection. They also stand out when it comes to flu-like symptoms (40% of all), with their number up at nearly 24,000 from over 19,000 a week ago.