Economy 11 April 2024, 11:02am

Flu epidemic keeps improving in Hungary, hospitalisations stagnate

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Due to seasonal factors and a four-day weekend (Good Friday + Easter Monday) authorities registered a further decline in the number of people seeking medical help with acute respiratory infection (ARI), including influenza-like symptoms on the 14th week of 2024. The number of people hospitalised with severe acute respiratory infection (SARI) has remained essentially unchanged, though.

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 (111.9) was higher than currently only twice in the past 12 cold seasons, in 2021/22 and 2022/23.

For the 52nd week of 2023, the NNK published only a couple of figures, hence the gaps in the graphs.

On the 14th (shortened) week of 2024, a total of 120,800 people sought medical help with acute respiratory infection (ARI), of whom 10.800 (8.9%) had flu-like symptoms. The former figure marks a 25.2% decrease after a 22.3% w/w drop, while the latter is a third lower than a week earlier, after a 30.5% drop over the 12th 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 slightly more than half of the weeks so far, between the 47th week of 2023 and the 7th week of 2024.

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 (113 in total on a national level last week, down from 158 a week ago).

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 4.4% on the 13th week, but widened to 8.8% on the 14th week.

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 14th week, the Covid positivity rate continues to be the highest, but the flu positivity rate is coming up and might eventually catch up. It has time to do so until the 20th week when the NNGYK stops publishing epidemiological data for this flu season.

The share of coronavirus in all samples tested (orange lines) was a lot smaller a year ago (10.1%) than currently (16.3%), while the percentage of influenza in the samples (green lines) is considerably lower now (15.4%) than in the period between the 40th week of 2022 and 14th week of 2023 (44.1%).

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 5.1% on the 14th week this year versus 10.2% a year ago. Note that these are the percentages of the select pathogens found in all samples tested up to the 14th week.

People tested positive for influenza and RSV had to be hospitalised for the 17th consecutive week in this flu season. The 47th week was the first one when one of the samples showed influenza infection (up at 1,010 in total by the end of the 14th week). Other pathogens identified between the 40th and 14th week were SARS-CoV-2 (1,069), respiratory syncytial virus (RSV, 334), adenovirus (6), parainfluenza (8), human metapneumovirus (HMPV, 146, and rhinovirus (53).

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 2022, 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 with a further decline on subsequent weeks. The share of influenza patients of all people in hospital is lower now (4.7%) than a year go (6.0%). (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. The number of people treated with RSV in hospitals dropped, and their share as a percentage of all people hospitalised with SARI went down to 21.9% after rising to 26% on the 13th week, and remains way higher than a year ago (3.0%) when only 5 people with RSV were in hospital against 28 currently.

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

There were 128 people with SARI in hospital on the week under review, up from 127 a week earlier. 13 of them were in the ICU, which corresponds to a 10.2% ratio, which figures compare with 18 and 14.2% a week earlier.

The NNGYK did not say this time how many of those in hospital with SARI were children aged 2 years or younger or people over 60 years of age. What we do know is that more than two thirds of RSV patients were aged 2 years or younger (19 out of 28) and that two out of the three COVID-19 patients were over 60.

Fewer children get sick

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, but after 11 consecutive months they are no longer on top in the flu rankings (23.8%), as the hardest-hit cluster has become the 15-34 age group (36.1%). 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 13th week this year, about 51,000 children sought medical help with ARI, a decline of some 30,000 from a week ago, They represented 42.2% of all people that turned to the doctor with some respiratory infection. There were 2,570 children in this age group with flu-like symptoms on the 14th week, down from over 5,500 a week earlier.