Pandemic flu and seasonal flu, what’s the difference?

Pandemic flu and seasonal flu, what’s the difference?

March 22, 2019


March 22, 2019 - As winter is drawing to a close, we are also coming out of peak seasonal flu season. The influenza virus is one of the world’s greatest infectious disease challenges and has affected us for centuries.  Its first recorded pandemic wave was in 1918 and the United States and countries all around Europe were affected. It’s estimated that 500 million people were infected and approximately 50 million died as a cause of this pandemic, with about 675,000 deaths occurring in the United States alone. Even today, influenza is still a major public health threat; just this past year, between October 2018 and February 2019, there were approximately 17.7 – 20.4 million cases of the flu reported and about 8.2 -2.6 million flu-related medical visits. The cases reported, fortunately, were incidences of seasonal flu rather than pandemic flu. However, as this virus affects us so frequently, it is important to understand the differences between seasonal and pandemic flu.

Seasonal and pandemic flu have more differences than they do similarities. Some of these differences include the frequency and scale of each flu. Seasonal flu typically peaks between December and February each year. They are more regional and affect a much smaller population than pandemic flu. Pandemic flu is an outbreak of the virus on a global scale. It affects multiple countries and those that feel its impact the most are middle and low-income countries. It is also not as common as the seasonal flu, as there have only been four pandemic waves in the 20th century:


These are some of the other similarities and differences between seasonal and pandemic influenza:


Seasonal Flu

Pandemic Flu

At risk groups

Affects young children, people 65 years and older, pregnant women and people with long term medical conditions the most. This is due to weaker immune systems that make these groups more susceptible.

Hard to determine who may be affected because it’s a new strain of the virus. Although the previously mentioned groups are more susceptible, past pandemics have impacted young adults as well.

Mode of transmission

Transmitted from person to person through droplets made when someone with the flu coughs, sneezes or talks near a person that is not infected.

Pandemic flu is transmitted similarly to seasonal flu but is more likely to impact a larger amount of people.


Many organizations such as the CDC and FEMA are working to increase pandemic flu preparedness. The CDC, for instance, has developed the Influenza Risk Assessment Tool (IRAT), a tool that will help to identify new strains of the virus that need vaccines developed before they reach pandemic status. FEMA has developed guidelines that outline response plans and key resources specifically for a pandemic. This guide prepares the different critical infrastructure sectors for surge events in addition to describing how to respond to an outbreak. These preparedness measures are important because of the possibility of another pandemic outbreak. Dr. Wenqing Zhang, the WHO Global Influenza Program manager, stated during the Readiness for Microbial Threats 2030: Exploring Lessons Learned Since 1918 influenza pandemic workshop in 2018, that “time is running out before the next pandemic hits”.

On a more individual level of preventative care, every year flu vaccines are made widely available at local healthcare facilities and can even be found free of charge. Receiving the flu vaccine will reduce the spread of the virus. Other preventative actions such as washing your hands or keeping warm are also great ways to avoid getting sick.

Flu outbreaks can strain hospitals and impact the supply chain, but Healthcare Ready can help mitigate these impacts with preparedness initiatives and communication between public and private sector partners. With this collaboration, we help inform communities, especially those with high populations of at-risk groups, on the differences between seasonal and pandemic flu. This is important to minimize the impact the flu has on communities to make sure as many people as possible have a flu-free winter in coming years.

Zebib Gebretensae

Zebib Gebretensae is a Program Analysist for Healthcare Ready. Her role entails working on the Health Security portfolio and data analysis of the International Poll conducted in 2018 as well as providing support for a wide variety of programs.

Zebib was born and raised in Addis Ababa, Ethiopia and is a recent graduate of Agnes Scott College, Atlanta Georgia, with a bachelor’s degree in Chemistry and minors in Public Health and Biology. During her undergraduate career at Agnes, she was involved in the African Students Association as a Public Relations executive as well as an International student representative in the institutions’ Honor Court. She volunteered with the HERO organization that focused on health education and resources for college students as well as MedShare, to help in categorizing medical supplies before shipping. Lastly, Zebib served as an undergraduate researcher at Agnes Scott College, working with metals and amino acids found within the body to better understand the hallmarks of senile dementias such as Alzheimer’s and Parkinson’s disease.

She is excited to be a part of the Healthcare Ready team as it will allow her to learn about the importance of disaster preparedness. It will push her to learn about the dynamic health systems in different countries as well as get experience with industries outside of academia.