Economy 14 March 2024, 12:02pm

Influenza epidemic in retreat in Hungary, with slow improvement in hospitals

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The number of Hungarians seeking medical help with acute respiratory infection (ARI), including influenza-like symptoms has dropped further on the 10th week of 2024, in line with seasonality. While there were fewer people treated in hospital with severe acute respiratory infection (SARI), more of them needed intensive care.. Almost 30% of those in hospital are treated with respiratory syncytial virus (RSV) infection and more than 90% of them are children aged 2 and younger, while now "only" half of Covid patients are aged 60 and older versus almost three quarters two weeks earlier.

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 (385.5) was higher than currently two times in the past 12 cold seasons (in 2017/18, and 2022/23).

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 10th week for a closer look.

THE EPIDEMIOLOGICAL CURVE dropped FURTHER FOR THE fourth CONSECUTIVE WEEK.

On the 10th week of 2024, a total of 232,800 people sought medical help with acute respiratory infection (ARI), of whom 37,300 (16.0%) had flu-like symptoms. The former figure marks a 7.6% drop and the latter a 16.2% decline over the 9th week.

We can also compare the ARI and flu numbers for 100,000 inhabitants. The epidemic has been more severe in this respect in 2023/24 than in 2022/23 in about half of the weeks so far.

We need to note that this year authorities perform more tests than a year ago, even though the number of samples tested remains extremely low (309 in total on a national level last week, down from 324 a week ago).

The COVID-19 positivity rate edged up a tad 1.3% from 1.2%, and the influenza positivity rate plummeted to 12.3% from 24.1% (and 36.9% on the 8th week). The positivity rate for the respiratory syncytial virus (RSV), however, rose to 10.4% from 9.9%.

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. The gap has widened considerably, reaching 38.8% percentage points on the 6th week and has since then come down to 11.0%.

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 it can serve as a kind of guidance. The influenza positivity rate was certainly way higher a year ago, and the Covid positivity rate is also lower currently, while the RSV rate was lower a year ago.

As regards all samples tested up to the 10th week, the Covid positivity rate continues to be the highest, but the flu positivity rate is coming up fast and may catch up shortly.

The share of coronavirus in all samples tested (orange lines) was a lot smaller a year ago (10.6%) than currently (18.3%), while the percentage of influenza in the samples (green lines) is considerably lower now (16.2%) than on the tenth week of 2023 (42.1%).

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 4.4% on the 10th week this year versus 10.9% a year ago. Note that these are the percentages of the select pathogens found in all samples tested up to the 10th week.

People tested positive for influenza and RSV had to be hospitalised for the 13th consecutive week in this flu season. The 47th week was the first one when one of the samples showed influenza infection (up at 941 in total by the end of the 10th week). Other pathogens identified between the 40th and 10th week were SARS-CoV-2 (1,064), respiratory syncytial virus (RSV, 257), adenovirus (6), parainfluenza (6), human metapneumovirus (HMPV, 79, and rhinovirus (47).

THERE WERE 262 PEOPLE IN HOSPITAL WITH SARI ON THE 10TH WEEK, VERSUS 284 A WEEK AGO and the peak at 357 on the 8th week. 2.3% OF THEM WERE TREATED WITH COVID-19, DOWN FROM 3.5% A WEEK EARLIER, WHILE 11.8% OF THEM WERE TREATED WITH INFLUENZA, DOWN sharply FROM 22.5% ON THE 9TH WEEK. THE SHARE Of RSV PATIENTS rose slightly to 29.0% from 27.8%.

The graphs below show a comparison with the previous 'flu season'. In 2022/23, there were no reports of people with Covid in hospitals up to the end of the year, 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). In this respect, the Covid situation is now a lot better.

The following chart depicts the number and share of people infected by influenza virus who had to be hospitalised. As you can see (orange columns, light blue curve), this 'flu season' was worse in this respect than the previous one up to the 8th week, but we see a turnaround on the 9th week and a sharp drop on the 10th week. The share of influenza patients of all people in hospital is way lower now (11.8%) than a year go (20.9%). 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' up to the sixth week, but there was a turnaround on the 7th week. While the number of people treated with RSV in hospitals dropped moderately, their share as a percentage of all people hospitalised with SARI edged up to 29% and remains way higher than a year ago (11.2%) when only 30 people with RSV were in hospital against 76 currently.

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 262 people with SARI in hospital on the week under review, down from 284 a week earlier. 39 of them were in the ICU, which corresponds to a 14.9% ratio, which figures compare with 31 and 10.9% a week earlier.

52.7% of those hospitalised with SARI were children aged 2 years or younger (up from 46.5% a week ago and the highest in this flu season yet), while 22.5% of them were aged 60 and over (unchanged from the 9th week). For the fifth 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.

We have no current data on the ongoing administration of flu shots, only figures for the past five flu seasons. These show that demand for vaccination surged during the coronavirus pandemic, and then petered out largely to previously observed levels. (Note that these figures show only the administration of free-of-charge 3FLUART influenza vaccine, i.e. they do not include shots GPs can prescribe at the request of their patients.)

We also know that merely 1.3% of the 3-18 age group got these free-of-charge flu shots in the 2022/23 flu season, following 1.7% in 2021/22, 3.9% in 2020/21, 1.4% in 2019/20, and 1.3% in 2018/19.

More than half of those with ARI are children

Finally, we have an age breakdown both for ARI and flu patients. Children up to the age of 14 are on top of the ARI age rankings in terms of numbers, and for the seventh 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 ARI 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 ARI, 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 10th week this year, about 119,000 children sought medical help with ARI, 51.1% of all people that turned to the doctor with some respiratory infection. They also stand out when it comes to flu-like symptoms (almost 42% of all), with their number down at 15,500 from over about 18,800 a week ago.