Flu shot less effective for obese adults

June 6, 2017
influenza
Electron microscopy of influenza virus. Credit: CDC

Although influenza vaccines are currently the best forms of protection to safeguard people against getting the flu, they are not effective in all cases. A study from Melinda Beck's research team at the University of North Carolina at Chapel Hill in the US found that obese people - despite getting their shots - were still twice as likely to develop influenza or flu-like illnesses than others of healthy weight. The findings are published in Springer Nature's International Journal of Obesity.

Obesity is of growing concern worldwide, as it often goes hand in hand with many health problems. Along with age, pregnancy and certain chronic diseases, obesity is also recognised as a factor that increases people's risk of dying from influenza.

Lead author Scott Neidich compared 1022 adults from North Carolina who were , overweight or obese. They had all received the seasonal trivalent inactivated influenza vaccine (IIV3) during the 2013-2014 and 2014-2015 flu seasons. Laboratory tests and symptom scores were used to confirm whether a vaccinated participant had flu or influenza-like illness and to which degree their bodies produced influenza-fighting antibodies following vaccination.

A small percentage of people became ill, despite receiving the shot. In the case of obese participants, 9.8 percent of them had either confirmed influenza or influenza-like illnesses, compared with 5.1 percent of those of healthy weight.

"Vaccinated are twice as likely to develop influenza and influenza-like illnesses compared to vaccinated healthy weight adults," says co-author Beck, who speculates that this is due to the fact that the T cells of do not function properly. These cells support the protection and recovery from influenza, and the researchers have previously reported obese people have impaired T cell responses to influenza vaccine.

As part of the study, serum samples were taken before and after participants received their shots. These were used to compare the antibody levels in vaccinated participants who became ill despite having received the preventative measure. The samples were tested using the Hemaglutination Inhibition Assay (HAI). This widely used test indicates how many antibodies have built up in the body to fight off an infection such as influenza, and is used to evaluate candidate .

The researchers found no differences in the antibody counts between vaccinated participants who did not report any symptoms and those who did, or between obese participants or people of healthy weight. The test was also unable to reliably predict whether a vaccinated would have enough protection against influenza or not.

This finding challenges the current standard blood tests being used to indicate whether a person has enough protection against influenza or not. According to Neidich, such tests could, especially in the case of obese people, "provide misleading information". The findings suggest that the effectiveness of influenza vaccines and other high-dose vaccine preparations should be reassessed for use in obese adults, to ensure that these provide accurate measurements.

"Impaired cell functioning, despite the robust production of antibodies, may make vaccinated obese adults more susceptible to ," suggests Neidich. "Alternative approaches may be needed to protect obese adults from both seasonal and pandemic virus infections."

Explore further: Study: Obesity limits effectiveness of flu vaccines

More information: S D Neidich et al, Increased risk of influenza among vaccinated adults who are obese, International Journal of Obesity (2017). DOI: 10.1038/ijo.2017.131

Related Stories

Study: Obesity limits effectiveness of flu vaccines

October 25, 2011
People carrying extra pounds may need extra protection from influenza.

Maternal vaccination again influenza associated with protection for infants

July 5, 2016
How long does the protection from a mother's immunization against influenza during pregnancy last for infants after they are born?

Patients with flu-associated pneumonia less likely to have received flu vaccine

October 5, 2015
Among children and adults hospitalized with community-acquired pneumonia, those with influenza-associated pneumonia, compared with those with pneumonia not associated with influenza, had lower odds of having received an influenza ...

Vaccines fail to protect obese mice from severe influenza infections

August 2, 2016
A study led by St. Jude Children's Research Hospital found that obese mice are not protected against influenza infections by vaccines that include adjuvants, raising concerns about vaccine effectiveness in obese humans who ...

Vaccine strategy induces antibodies that can target multiple influenza viruses

July 22, 2016
Scientists have identified three types of vaccine-induced antibodies that can neutralize diverse strains of influenza virus that infect humans. The discovery will help guide development of a universal influenza vaccine, according ...

Study shows high-dose flu vaccine more effective in elderly

August 13, 2014
High-dose influenza vaccine is 24 percent more effective than the standard-dose vaccine in protecting persons ages 65 and over against influenza illness and its complications, according to a Vanderbilt-led study published ...

Recommended for you

Kids with weight issues at high risk of emotional and behavioural problems

August 10, 2017
A new, in-depth study of New Zealand children and teenagers seeking help with weight issues has found their emotional health and wellbeing is, on average, markedly worse than that of children without weight issues.

Study finds 90 percent of American men overfat

July 24, 2017
Does your waist measure more than half your height?

Are sugary drink interventions changing people's behaviour?

July 19, 2017
An evaluation of efforts designed to reduce how many sugary drinks we consume shows some success in changing younger people's habits but warns they cannot be the only way to cut consumption.

Young adult obesity: A neglected, yet essential focus to reverse the obesity epidemic

July 18, 2017
The overall burden of the U.S. obesity epidemic continues to require new thinking. Prevention of obesity in young adults, while largely ignored as a target for prevention and study, will be critical to reversing the epidemic, ...

Weight gain from early to middle adulthood may increase risk of major chronic diseases

July 18, 2017
Cumulative weight gain over the course of early and middle adulthood may increase health risks later in life, according to a new study led by researchers from Harvard T.H. Chan School of Public Health. They found that, compared ...

Study finds children carry implicit bias towards peers who are overweight

June 23, 2017
Even children as young as 9 years old can carry a prejudice against their peers who are overweight, according to a new study led by Duke Health researchers. They might not even realize they feel this way.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.