13 October 2022

BMI professor behind the world's largest randomized trial

The new Danflu-2 study is now in the air, and the aim is for approx. 200,000 Danes in the age group + 65 to participate over the next two years. There will be drawn lots between the participants, so half will receive a high dose, while the other half will have a standard dose, which is the only one available in the Danish vaccination programme this year.

The aim of the experiment is to investigate whether a high-dose influenza vaccine is better than the standard dose when it comes to preventing hospitalisation and death for citizens over 65 years.

“Influenza affects a lot of people every year and can potentially be serious – so it is important that research is conducted into the type of vaccine that protects against severe Influenza disease. If the hypothesis lasts, and high-dose vaccines prove to be able to give, for example, fewer hospitalisations, the research can benefit both the individual citizen and society,” says Doctor and Professor Tor Biering-Sørensen.

Tor Biering-Sørensen leads the Centre for Translational Cardiology and Pragmatic Randomized Experiments, which is behind Danflu-2. The centre is a collaboration between Department of Biomedical Sciences and Herlev and Gentofte Hospital.

Results from pilot study suggest effect

The study is a follow-up on the pilot study Danflu-1 from 2021, where approx. 12,500 citizens over 65 years participated.

The results from the study were presented this month at the International Heart Congress, ESC, and showed that due to influenza or pneumonia, the risk of hospitalisation was 64 per cent lower at a high-dose influenza vaccine than in the standard dose vaccine, which is the vaccine we use today in Denmark. There was also an observed halving in the proportion of deaths for all reasons in the case of the high-dose vaccine compared with the standard dose influenza vaccine.

However, the study was not designed to investigate the effect of high-dose influenza vaccines on hospitalisations, and there is therefore a need for a larger study in order to be able to say something definitive.

Will put Denmark on the world map

In itself, it is unique to be able to carry out a study of this size, where all the information about the people involved in the study comes directly from the Danish registers and not from the test participants themselves.

"The study here will put Denmark on the world map as a place where you can quickly get valid data, in a very fast way, which can provide definitive answers to the possibilities for treating citizens in order to prevent illness and death," says Tor Biering-Sørensen.


The study is a randomised controlled study in which the target is for 104,000 participants to receive a standard dose and 104,000 receive the high dose over the next two years. With the help of the Danish registers, the researchers will be able to monitor the progress of the disease.

High-dose means that the vaccine contains four times as much inactivated influenza virus material as the standard dose (60 versus 15 microgram). Both high and standard doses contain four different virus strains.

In previous studies, the high dose has been found to prevent influenza infections 24% better than the standard dose vaccine and has not been seen to result in more serious side effects than the standard dose. A bit more severe local reactions have primarily been observed on the injection site at a high dose.

In 2020, the high-dose influenza vaccine was approved in Denmark, where it was used last year and offered to citizens over the age of 82. This year, this is not part of the Danish vaccination scheme. 

The study is carried out in collaboration with the Danish doctors' vaccination service, and you can read more about the study programme and register here.

Press relations:
Doctor, Professor Tor Biering-Sørensen 28933590 or via Press Consultant Andreas Bennekou, Herlev and Gentofte Hospital, 38673040