Through data-based forecasting, researchers are trying to better predict the number of flu cases.
October 2023- The Journal of Healthcare Contracting
Fall is here, and that means flu cases are on the rise. Symptoms of the flu such as coughing, body aches, and fever are very similar to those associated with COVID-19, making it more important during flu season for disease prevention. As health professionals continue to navigate the impacts of COVID-19 on respiratory season, prevention and forecasting tools are helping health systems prepare for flu season.
Influenza (flu) is a contagious respiratory illness that infects the nose and throat and is spread through tiny droplets when an infected individual coughs, sneezes, or talks. The flu causes symptoms including fever, cough, sore throat, runny nose, muscle aches, fatigue and more. Each season, anywhere from 3% to 11% of the population is infected with the flu, according to the Centers for Disease Control and Prevention, and approximately 8% of the U.S. population gets sick from the flu in an individual season.
Flu infection is highly contagious and very common, especially in children and adults. These groups are more likely to develop a symptomatic flu infection, however the immunocompromised, young children, and older adults are more likely to develop a severe infection that can lead to hospitalization.
Influenza places a large disease burden on the U.S. each year. An estimated 9 million flu illnesses were reported in the 2021-2022 flu season, according to the CDC. Mitigation measures intended to prevent the spread of COVID-19 may have been a result of last season’s lower flu case numbers. In the 2019-2020 season, prior to the pandemic, flu cases were much higher, with an estimated 36 million flu-related illnesses, 16 million flu-related medical visits, 390,000 flu-related hospitalizations, and 25,000 flu-related deaths, according to a CDC research study.
So, how do researchers know what flu season will look like, what healthcare workers can expect during respiratory season, and how to stay healthy and prevent infection this fall?
Fall ahead of the flu
The CDC has a system used to determine future flu-related disease outcomes. By analyzing hospital and health-related data, the CDC makes predictions as to what the upcoming flu season will look like. The CDC’s flu forecasting model allows physicians to plan for flu season and act in advance to keep communities healthy and prepared for respiratory season.
Traditional influenza surveillance systems measure flu activity while it is occurring or after it has occurred. Flu forecasting, however, provides researchers with information about potential future health outcomes.
Flu forecasting efforts began with the CDC’s “Predict the Influenza Season Challenge,” in 2018, which encouraged academic and private industry researchers to get involved in forecasting possible outcomes of the 2013-2014 flu season. Since 2013, the Influenza Division of the CDC has collaborated with external researchers to provide the public with flu forecasting data and information.
“Flu forecasting offers the possibility of predicting what flu activity might look like before it happens. The CDC provides forecasting teams data, relevant public health forecasting documents, and forecast accuracy metrics which are compiled and communicated weekly,” said Matt Biggerstaff, Team Lead of the Applied Research and Modeling Team within the CDC’s Influenza Division.
Predictions for flu season’s public health forecasting targets are based on flu-related hospital admissions data from the U.S. Department of Health and Human Services (HHS) Protect hospital dataset.
Starting during the fall season when respiratory illness cases begin to increase, the forecasting teams, which include outside researchers such as the California Department of Public Health, Predictive Science Inc., Columbia University, and more, submit their hospitalization forecasts to the CDC. The weekly forecasts are compiled into a summary that consists of flu-related information that can be accessed online on the CDC website called FluSight.
“These research efforts have enabled the CDC and the forecasting community to prioritize future research and development and have helped public health officials better understand the best cases for forecasts and their current limitations,” according to Biggerstaff.
Forecasts can be used to anticipate changes in flu activity by helping inform the public health response during seasonal flu epidemics. Knowledge of these potential influxes in advance prepares the healthcare community for respiratory disease-related hospital surges. Predictions also serve to guide personal and community-based prevention strategies.
Community prevention
Flu forecasts are one of the main sources of data used by healthcare professionals to plan influenza prevention and mitigation strategies.
Community mitigation during flu season includes both reducing contact during times of high flu activity and health professionals conveying the importance of flu vaccination in areas with a predicted increase in flu activity.
“Flu forecasts can inform messaging to healthcare providers regarding antiviral treatment allocation, preparation for an influx of flu-related hospitalizations, and inform the distribution and placement of healthcare staff, hospital beds, and treatment resources,” said Biggerstaff. “Forecasts for flu and COVID-19 hospitalizations allow us to better understand the potential combined future burden of these diseases on the healthcare system.”
To prevent the spread of the flu, individuals should receive an annual flu vaccine. Everyone six months of age and older are eligible for a flu shot to reduce the risk of severe disease due to the flu virus. During the 2019-2020 flu season, the CDC estimates that flu vaccinations prevented nearly 105,000 flu-related hospitalizations.
Staying healthy during flu season also includes preventative action such as avoiding close contact with people that are sick, covering coughs and sneezes, frequent hand washing, and cleaning and disinfection of surfaces that may be contaminated.
According to Biggerstaff, “When forecasts accurately predict flu activity, more effective planning of public health responses to seasonal flu epidemics and flu pandemics is possible.”
Sidebar:
Flu stats
9 million
An estimated 9 million flu illnesses were reported in the 2021-2022 flu season, according to the CDC
36 million
In the 2019-2020 season, prior to the pandemic, flu cases were much higher, with an estimated 36 million flu-related illnesses
105,000
During the 2019-2020 flu season, the CDC estimates that flu vaccinations prevented nearly 105,000 flu-related hospitalizations