Stylized cityscape with snowflake-like virus particles, representing coronavirus seasonality.

Coronavirus Seasonality: What to Expect Each Winter

Lena Voss in Health & Wellness December 2025 • 4 min read.

"Unraveling the trends of common human coronaviruses to better prepare for future respiratory virus seasons."

Human coronaviruses (HCoVs) are a group of viruses known to cause respiratory infections, ranging from the common cold to more severe conditions. Among these, OC43, 229E, NL63, and HKU1 are frequently detected, particularly during winter months. Understanding their behavior and prevalence is crucial for public health preparedness.

Recent advances in diagnostic technologies have improved our ability to identify and track these viruses. Since 2014, voluntary reporting of HCoV data to the National Respiratory and Enteric Virus Surveillance System (NREVSS) has provided valuable insights into their seasonal patterns.

This article explores the trends of HCoV infections based on data reported to NREVSS, focusing on the seasonality, age distribution, and potential impact of different strains. By understanding these patterns, we can better anticipate and manage future respiratory virus seasons.

Seasonal Trends of Human Coronaviruses

Stylized cityscape with snowflake-like virus particles, representing coronavirus seasonality.

A comprehensive study reviewed weekly aggregate test results for HCoV OC43, 229E, NL63, and HKU1, voluntarily reported to NREVSS by U.S. hospitals and clinical laboratories from July 1, 2014, to April 30, 2017. The data revealed distinct seasonal patterns and variations in the prevalence of each virus.

Key findings from the study include:

Peak Seasonality: The percentage of positive tests for HCoV generally peaked between December and March, indicating a strong winter seasonality.
Strain-Specific Patterns: HCoV-OC43 showed distinct annual peaks with variations in magnitude by year. HCoV-HKU1 and NL63 had similar patterns, with notable peaks during winter 2016 compared with 2015 or 2017. HCoV-229E showed a discernable peak in 2017 compared with the previous 2 years.
Age Distribution: Analysis of individual-level data reported via the Public Health Laboratory Interoperability Project (PHLIP) showed that age distribution differed between HCoV types.

These findings underscore the importance of continued surveillance and testing to monitor the circulation of HCoVs and understand their impact on public health. The observed differences in seasonality and age distribution highlight the need for targeted prevention and control strategies.

Preparing for Future Coronavirus Seasons

The research emphasizes that peak positivity for HCoV occurs during winter months, with notable annual differences in circulation by HCoV type. This highlights the need for ongoing awareness and proactive measures to mitigate the spread of these viruses.

Continued testing and surveillance are crucial for further characterizing circulation trends over time and by geographic region. Such efforts will enhance our understanding of HCoV's contribution to the winter respiratory virus season and inform public health strategies.

By staying informed about these patterns and practicing preventive measures, individuals and communities can better navigate future coronavirus seasons and protect public health.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

What are the different types of human coronaviruses discussed?

Human coronaviruses (HCoVs) such as OC43, 229E, NL63, and HKU1 are a group of viruses that commonly cause respiratory infections, ranging from the common cold to more severe conditions. They are frequently detected during the winter months. Understanding their behavior is important for public health preparedness, helping to inform strategies to mitigate their spread and impact.

What is the National Respiratory and Enteric Virus Surveillance System (NREVSS), and why is it important?

The National Respiratory and Enteric Virus Surveillance System (NREVSS) is a system where hospitals and clinical laboratories voluntarily report data on human coronaviruses. Since 2014, this data has provided valuable insights into the seasonal patterns of HCoVs. Analyzing data from NREVSS helps public health officials track the prevalence of viruses like OC43, 229E, NL63, and HKU1, and understand their impact on public health.

When do human coronaviruses typically peak?

The winter months, typically from December to March, are when the percentage of positive tests for HCoVs generally peaks. This seasonal pattern means that these viruses, including OC43, 229E, NL63, and HKU1, are more prevalent during the colder months. This seasonality underscores the need for public health strategies focused on mitigating the spread during these periods.

Do all human coronaviruses behave the same way?

Specific strains like HCoV-OC43, HCoV-HKU1, NL63 and HCoV-229E show varying patterns. HCoV-OC43 had distinct annual peaks, while HCoV-HKU1 and NL63 demonstrated similar patterns. HCoV-229E showed a notable peak in 2017 compared to the prior two years. These differences are crucial because they highlight that each virus may behave differently. This information is essential for developing targeted prevention and control measures.

Why is age distribution relevant when discussing human coronaviruses?

The age distribution of different HCoV types varies. The Public Health Laboratory Interoperability Project (PHLIP) provided individual-level data that showed age distribution differing between HCoV types. This means certain strains may affect particular age groups more significantly. Understanding these patterns is vital for creating effective, targeted prevention strategies and allocating resources to protect vulnerable populations.