A Gram Research analysis of Danish health data found that about 32% of adults experience at least one infection per year, with respiratory infections being the most common type. Researchers tracked 609,224 people by combining health surveys with hospital and pharmacy records, identifying 315,689 total infections over one year—most treated with antibiotics at home rather than in hospitals. This large database enables scientists to investigate how lifestyle factors like smoking, exercise, and diet influence infection risk.
Researchers in Denmark created a massive database combining health surveys with hospital and pharmacy records to understand how often people get infections. They tracked over 600,000 adults for one year and found that about one in three people had at least one infection—mostly respiratory infections like colds and flu, treated with antibiotics. This resource will help scientists study why some people get more infections than others and how lifestyle factors like smoking, exercise, and diet affect infection risk. The database includes detailed information about participants’ daily habits, making it possible to answer many unanswered questions about infectious diseases.
Key Statistics
A 2026 cohort study of 609,224 Danish adults found that 32.3% experienced at least one infection within 365 days, with 315,689 total infections recorded—including 25,385 hospital-diagnosed and 290,304 community-treated infections.
Respiratory infections accounted for 34.9% of all infections in the Danish Infection Cohort study, making them the most common infection type among 609,224 tracked adults.
Antibiotics were prescribed in 80.6% of infection cases in the Danish Infection Cohort, demonstrating that systemic anti-infective medications are the primary treatment for community-managed infections.
The Quick Take
- What they studied: How often infections occur in the general population and what factors might make some people more likely to get infected
- Who participated: Over 609,000 Danish adults aged 18 and older who completed health surveys between 2010 and 2021
- Key finding: About 32% of people had at least one infection within a year, with respiratory infections being the most common type, and most infections were treated with antibiotics in the community rather than in hospitals
- What it means for you: This research creates a tool for scientists to better understand infection patterns and identify which lifestyle choices might help prevent infections, though individual results will vary based on personal health factors
The Research Details
Scientists combined three types of information from Denmark’s health system: answers from national health surveys where people reported their habits and health, hospital records of infections that required medical care, and pharmacy records showing when people filled antibiotic prescriptions. They followed people for one year after they completed surveys in 2010, 2013, 2017, and 2021, creating a large database of real-world infection experiences.
This approach is powerful because it captures both serious infections that sent people to the hospital and milder infections treated at home with antibiotics from pharmacies. By linking survey responses about lifestyle (smoking, exercise, diet, alcohol use) with actual infection records, researchers can investigate whether these habits influence infection risk. The study included detailed information about participants’ weight, physical activity levels, and other health factors.
Most infection research relies on hospital records alone, which misses the majority of infections that people treat at home. By including both hospital and community-treated infections, this study captures the full picture of how often infections actually occur. The combination of lifestyle information with infection records allows researchers to test whether specific habits protect against or increase infection risk—something that couldn’t be done before.
This is a large, population-based study using official health records rather than relying on people’s memory, which makes the infection data very reliable. The study includes diverse age groups and follows real-world infection patterns. However, the data only covers Denmark, so results may not apply equally to other countries with different healthcare systems or populations. The study also depends on people accurately reporting their lifestyle habits in surveys.
What the Results Show
Among the 609,224 people studied, 196,980 individuals (about 32%) had at least one infection within 365 days after completing their survey. The total number of infections recorded was 315,689—meaning some people had multiple infections during the year. Hospital-diagnosed infections were relatively rare, with only 11,850 cases, while community-treated infections were much more common at 185,130 cases. This shows that the vast majority of infections are handled outside hospitals.
Respiratory infections—including colds, flu, and bronchitis—were by far the most common type, accounting for 34.9% of all infections. Antibiotics were the most frequently prescribed anti-infective medication, used in 80.6% of cases. This large dataset provides a realistic picture of infection patterns in a modern developed country, showing that infections are extremely common in everyday life.
The study identified that infections occurred across all age groups and demographic categories in the population. The database captured seasonal patterns and variations in infection types, providing researchers with detailed information about when and how infections spread through the community. The inclusion of lifestyle data means future research can examine whether factors like smoking status, physical activity levels, diet quality, and alcohol consumption influence infection risk.
Previous infection studies often relied only on hospital records, which captured only the most severe cases. This research expands our understanding by including the much larger number of infections treated in the community. The finding that about one-third of people experience infections annually aligns with other population studies but provides more complete data because it combines multiple sources of information.
The study only includes people in Denmark, so the results may not apply to countries with different healthcare systems, climates, or populations. The data depends on people accurately reporting their lifestyle habits in surveys, which can be unreliable. Some infections may not be captured if people didn’t visit a hospital or pharmacy, or if they used over-the-counter treatments instead of prescription antibiotics. The study is observational, meaning it can show patterns but cannot prove that lifestyle factors directly cause differences in infection risk.
The Bottom Line
This research creates a valuable resource for future studies but doesn’t yet provide specific recommendations for preventing infections. Once scientists use this database to analyze the data, they may be able to identify which lifestyle factors most strongly protect against infections. For now, following general public health guidance about hygiene, vaccination, and healthy habits remains the best approach.
Public health officials, epidemiologists, and infection disease researchers should care about this resource. People interested in understanding their infection risk and how lifestyle affects health may find future studies using this data helpful. Healthcare systems can use these patterns to better prepare for seasonal infections.
This is a foundational research tool, not a treatment or intervention. The real benefits will emerge over the coming years as scientists use this database to answer specific questions about infection prevention and risk factors.
Frequently Asked Questions
What percentage of people get infections each year?
According to the Danish Infection Cohort study of 609,224 adults, approximately 32.3% of people experience at least one infection within a year. Most infections are treated with antibiotics at home rather than requiring hospitalization.
What type of infection is most common?
Respiratory infections like colds, flu, and bronchitis are the most common, accounting for 34.9% of all infections in the Danish study. These infections are typically treated with antibiotics prescribed at community pharmacies.
How can lifestyle factors affect infection risk?
The Danish Infection Cohort database includes detailed information about smoking, weight, physical activity, diet, and alcohol use, enabling future research to identify which lifestyle habits protect against or increase infection risk—though specific protective factors haven’t yet been determined.
Why is this research important for understanding infections?
This study captures both serious infections requiring hospitalization and milder infections treated at home, providing a complete picture of infection patterns. Previous research relied only on hospital records, missing the majority of infections that occur in the community.
Want to Apply This Research?
- Track respiratory infections monthly by logging any colds, flu, or bronchitis diagnoses and noting whether you received antibiotic treatment, allowing you to identify your personal infection patterns over time
- Use the app to correlate infection occurrences with lifestyle factors you’re tracking—such as sleep quality, exercise frequency, and stress levels—to identify which habits seem associated with fewer infections in your own life
- Maintain a year-long infection log within the app that records infection type, treatment method, and associated lifestyle factors, then review quarterly to spot trends and adjust health behaviors accordingly
This research describes infection patterns in a Danish population and creates a resource for future studies. It does not provide medical advice or treatment recommendations. Individual infection risk varies based on age, immune system health, vaccination status, and other personal factors. If you suspect you have an infection, consult a healthcare provider for diagnosis and treatment. This information is for educational purposes and should not replace professional medical guidance.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.