Enzymatica has developed ColdZyme, a medical device designed to protect against viruses that cause cold and flu-like symptoms in the upper respiratory tract. The spray works by forming a protective barrier in the throat, preventing viruses from attaching to and infecting cells, while limiting their spread. This mechanism can help reduce both the severity of symptoms and the duration of the illness.
After ColdZyme was CE certified, its effectiveness has continued to be evaluated. The results of two separate studies were recently published in The Journal of Physiology.
ColdZyme proven effective in shortening colds and reducing symptoms
The first study included athletes with naturally acquired upper respiratory tract infections (URTI) and was led by Glen Davison, professor of sport and exercise science at the University of Kent in the UK. Endurance athletes were randomly assigned to use either ColdZyme or a placebo spray at the first sign of infection. The study included data from 154 participants.
The results showed a significantly shorter symptom duration in the ColdZyme group, who also experienced milder symptoms according to the Jackson score. This resulted in fewer lost training days compared to the placebo group.
A significantly lower viral load was also observed in the ColdZyme group, which likely contributes to the reduced disease burden.
Professor Glen Davison's comment on the results
BioStock contacted Professor Glen Davison to find out more about the results.
ColdZyme users experienced significantly shorter illness durations, milder symptoms, and fewer lost training days. Can these results be transferred to the general public?
– Yes, absolutely. Our interest in, and selection of, athletes in this study is not due to differences in how they become infected or respond to infection or treatments such as ColdZyme. We were confident that we would get enough cases of the disease in this group, which I am also particularly interested in as a sports scientist. But there is no indication that the effects we saw – shorter symptom duration and lower viral load – would be different in other groups.
Based on your results – how and when should ColdZyme be used?
– Definitely at the first symptoms of a cold. It is important that the user follows the instructions and takes ColdZyme regularly – about 6 times a day – for best effect. Protective use, for example when staying among sick people or in crowded environments, is also wise.
The study also showed a significantly lower viral load in the ColdZyme group. How important is that finding?
– This is very important. It helps us understand the mechanism behind why ColdZyme works. Many symptoms of respiratory infections are caused by tissue damage and inflammation when cells in the respiratory tract are infected. Less virus likely means less damage, less inflammation – which makes it easier for the immune system to fight the infection and shorten the duration of the illness.
The study is based on self-reported data. Does this affect reliability?
– A strength of our study is that we also took samples to confirm infection. But self-reporting is actually very relevant here, because that is how people experience colds in real life. As long as you use the right tools – like the Jackson form – and rigorous analysis methods, the results are reliable. The combination of self-reporting and sampling makes our data very reliable.
Can you tell us more about the publication process and the significance of the study being accepted in The Journal of Physiology?
– This is a highly regarded and prestigious scientific journal, so we are very proud that the article was accepted for publication there. It is a peer-reviewed scientific journal that has been the flagship of The Physiological Society for almost 150 years.
– To be considered for publication at all, the manuscript must first be submitted, which is assigned to an editor-in-chief or an editorial team. They conduct an initial review to determine whether it is suitable for further consideration. If the article passes this initial review, it is sent to two or three recognized experts in the field.
– These review all aspects of the study and provide a recommendation to the editors whether the study should be rejected or whether it is “potentially acceptable” for publication. As part of this process, the reviewers usually have suggestions for revisions, clarifications, or improvements. If we receive a message that the study is potentially acceptable, we must respond to all comments and any questions.
– The reviewers were very tough – which we also expected from such a prestigious journal. But they considered it a well-done study and by following the process we were able to satisfy both the reviewers and the editors, who jointly concluded that it was worthy of publication. That is basically how scientific review – peer review – works.
– Since its publication in February, we have been very pleased with the attention the article has received. For example, it has already exceeded 2 full views and downloads from the publisher's website. The Altmetric Attention Score is also developing strongly (this is a measure of both the quality and amount of attention a scientific article receives online. See: https://www.altmetric.com/about-us/our-data/donut-and-altmetric-attention-score/).
– The Altmetric score for our article on April 10, 2025 places it among the 5% most-attentioned research publications ever tracked by Altmetric – and among the 3% most-attentioned in its age group (as older articles have had more time to accumulate attention). Not entirely unexpectedly, a large portion of the interest in the article seems to come from Sweden.
Reduced viral load
The second study included in the scientific publication confirmed a reduction in viral load when ColdZyme was used on cell culture models of human airway epithelial cells. The models simulated different parts of the upper respiratory tract, such as the nose and throat, and were infected with rhinovirus.
The results showed that epithelial cells pretreated with ColdZyme suffered less tissue damage and inflammation. Tissue cultures treated with ColdZyme showed minimal signs of infection, preserved cell structures and significantly fewer virus particles compared to those treated with saline.
Professor Wilflingseder explains the laboratory results
The in vitro study included in the article was led by Doris Wilflingseder, professor of infectious diseases at the Ignaz Semmelweis Institute and Vetmeduni Vienna. BioStock contacted Professor Wilflingseder to learn more about the results.
What motivated you to investigate the effect of ColdZyme in in vitro models of airway epithelium?
– During the first wave of the COVID-19 pandemic, when neither treatment nor vaccine was available, we wanted to investigate whether antiviral medical devices already on the market could be effective against this new threat. Since we had a standardized airway model available from previous research on Aspergillus fumigatus, we tested ColdZyme in our 3D model – and found it to be very effective. That’s where it all started.
Can you explain how the models mimic real upper respiratory tract infections?
– Our models mimic real infections very well. The model contains ciliated and mucus-forming cells as well as stem cells that renew the cell types. To give the cells a structure similar to that in the body, we mix them with an artificial extracellular matrix. After a four-week differentiation phase in the air-liquid phase, the cells are ready to be infected with the relevant respiratory virus.
How do your in vitro results complement the findings observed in the in vivo study?
– I believe that the in vivo and in vitro studies complement and strengthen each other. We saw a reduction in the amount of virus in both models. In the in vivo study, this is associated with shorter symptoms and in the in vitro study with preserved tissue integrity. The lower the amount of virus, the less tissue damage – and thus the shorter the symptom period.
What are the next steps to confirm these results?
– We are currently planning new combined in vitro and in vivo studies to mechanistically explain our findings even more deeply.
