Obesity and the Increased Risk for Seasonal Influenza

by Brenda Hoehn on Dec 14, 2023

Obesity and the Increased Risk for Seasonal Influenza

Obesity and the Increased Risk for Seasonal Influenza

Current research strongly suggests that obesity places individuals at an increased risk for seasonal influenza. Scientific findings show that excess weight can weaken the body’s immune responses, increase inflammation, may extend how long someone remains contagious and could impact the efficacy of the flu vaccine.

During the flu season, coughing, sneezing, and contaminated hands are obstacles for all of us. We can do our best to protect each other by coughing and sneezing into our elbows and consistently washing our hands. However, there are populations of individuals who stand at a higher risk for infection, including those with obesity.

The Flu: Description and Symptoms

According to the World Health Organization (WHO), influenza viruses cause the flu (seasonal influenza), an acute respiratory tract infection (RTI). There are four types of influenza viruses (types A, B, C, and D). However, influenza A and B are responsible for seasonal epidemics and pandemics.

Flu season commonly peaks between December and February, but flu activity can begin as early as October and continue into May. Symptom onset typically occurs two days after an individual has been infected:

  • Cough (generally dry)
  • Headache
  • Muscle and Joint Pain
  • Runny Nose
  • Severe Malaise
  • Sore Throat
  • Sudden Fever Onset

To date, numerous studies observing the impact of obesity on infectious diseases have established:

  • A link between obesity (BMI > 30) and elevated rates of respiratory tract infections (i.e., the flu).
  • Obesity can be a substantial risk factor for RTI hospitalization and death, such is the case with influenza A (seasonal flu) and the SARS-CoV-2 virus (COVID).

Obesity and Seasonal Influenza Hospitalization Rates

The 2009 swine flu (H1N1) pandemic saw higher hospitalization and mortality rates in the human population with obesity than that without. With that in mind, the 2011 study by Kwong, J. C. et al. set out to observe the link between obesity and hospitalizations from respiratory diseases during the flu season.

The study found that individuals with obesity (BMI >30) were more likely to experience hospitalizations than individuals with a normal BMI (BMI 18.5-24.9) during the flu season and concluded that severe obesity (BMI >40), regardless of an existing chronic condition, elevates an individual’s risk for hospitalizations during the flu season.

Excess Weight, Inflammation, and a Weakened Immune System

A 2023 study (Almond, M. et al.) recently provided new insights into the relationship between obesity and severe influenza case frequency.

The findings indicate that chronic inflammation from obesity weakens the body’s immune response to infections, increasing an individual’s susceptibility to respiratory diseases, including the flu. Additionally, scientists suspect (Aziz, R. et al.) that the resulting acute inflammation from RTIs worsens chronic inflammation, causing more severe disease and grave prognosis.

The study concludes with an acknowledgment that “…given that epidemiological evidence indicates that the clinical risk of influenza infection diminishes following bariatric surgery…,” additional research should investigate whether sustained weight loss may resolve the body’s impaired antiviral immunity.

The Flu: Obesity May Extend Infectious Period

In 2018, a published study (Maier, H. E. et al.) in The Journal of Infectious Diseases determined that adults with obesity and infected with influenza A were contagious approximately 1.5 times longer than adults without obesity—5.23 days vs. 3.68 days, respectively. The implications of this study’s findings suggest that as obesity rates continue to rise, so could the amount of influenza A cases with extended infectious periods. Thus, increasing the opportunities for the seasonal flu viruses to infect the already immunocompromised obese population.

Recent research also shows that the flu vaccine may be less effective in clinically obese individuals than in those with a clinically normal BMI.

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Boost Your Immunity with Daily Bariatric Supplements

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