A recent mouse study found that dietary interventions led to better metabolic biomarkers and improved flu vaccine response.
- The World Health Organization estimates that vaccination efforts
have saved 154 million lives in the last fifty years.
- Multiple factors can
influence vaccine effectiveness, and researchers are interested in
studying the best ways to increase vaccine efficacy.
- A study conducted in mice
with obesity found that dietary interventions resulting in weight
loss led to better metabolic biomarkers and improved flu vaccine
effectiveness.
- The results highlight the
potential impact of a balanced diet and metabolic health on vaccine
response.
The World
Health Organization (WHO) estimates that immunization efforts have helped save
However,
certain immunizations, such as the flu vaccine, are not always as effective as we’d like them to be due to
various factors.
A recent
mouse study examined how healthy dietary interventions prior to vaccination
could influence metabolic health and increase flu vaccine effectiveness. The
findings show that improved metabolic health led to better immune function,
which increased the vaccine response.
Future
research could explore how these findings, recently published in
The researchers
note that obesity is associated with a higher risk
of severe infectious diseases, including the flu.
While this heightened risk makes it more
critical for this group to get vaccinated, researchers note that obesity can
also decrease the effectiveness of flu vaccines.
For the
study, they tested a few different scenarios to see if dietary changes helped
prior to and after vaccination.
They took
two groups of mice and fed one group a lean diet and the other a high fat diet. The mice then received a flu
vaccine. After vaccination, some mice that were on the high fat diet were
switched to the control diet. Mice then received a lethal dose of the flu
virus, homotypic H1N1, after either 4 weeks or 12 weeks on the control diet.
Researchers
found that switching to a healthy diet post-vaccination
did not improve survival despite the weight loss that the previously obese mice
experienced.
The
previously obese mice had only a 24% survival rate after 4 weeks on the control
diet and a 28% survival rate after 12 weeks on the control diet. However, the
results suggested that dietary changes to lose weight after
vaccination may help control viral spread.
The
results were much different when the dietary changes were made pre-vaccination.
To test this, researchers had certain obese mice switch to the lean control
diet 4 weeks before vaccination. This switch allowed for several systemic
measurements of metabolic dysfunction to return to normal
and for weight loss to occur.
Researchers
observed an improved immune response in these mice, particularly among their T
cells, and decreased morbidity and mortality.
After exposure to the flu virus, the formerly
obese mice had a 100% survival rate. The results suggest that specific dietary
changes and weight loss may help improve the flu vaccine’s effectiveness.
The
research also adds to what we know about how obesity may impact immune
response, which will be an area for continued research.
“We have
known since the 2009 H1N1 flu epidemic that people with obesity are at
increased risk of severe flu and death, and we have seen similar findings with
COVID-19. It is not entirely clear why, however — it could be decreased lung
function and/or other factors,” non-study author Marci Drees, MD, chief
infection prevention officer and hospital epidemiologist for ChristianaCare,
told Medical
News Today.
“It’s important to remember that this study
was conducted in mice, and of course, mice are not humans — so it is certainly
not definitive in terms of proving that people with obesity don’t respond as
well to flu vaccines,” Drees said.
Effects of metabolic health on vaccine response not fully understood
The study’s main limitation is that it was conducted in mice,
meaning further investigation is needed before these findings could be applied
to humans.
Researchers
also note they were limited in their ability to determine certain factors, as
they had a low sample size of mice on the high fat diet who survived exposure
to the flu. They acknowledge the need for a more in-depth investigation of how
nutrition affects immune cell function during vaccination and infection.
“There
have been some small studies in the past that showed that people with obesity
were more likely to get the flu, even if vaccinated, compared to vaccinated
people who were not obese — and despite having good levels of antibodies against the flu strains in the
vaccines that year,” Drees said.
“There is a lot more that needs to be studied
in this area to better understand the interactions between obesity, the flu
virus, and the flu vaccine.”
Non-study
author Dr. Linda Yancey, director
of infection prevention at the Memorial Hermann Health System in Houston, noted
the following to MNT:
“First off,
this is a mouse study. It goes without saying that mice are not people. This
looks like a nice foundational study to base future human trials on. Studies
like these are more important than many people give them credit for because
they prove something that everyone generally agrees upon — a healthy diet and
weight loss are good for you. While we all believe this to be true, it is nice
to see solid scientific data backing this up.”
Will obesity impair the flu vaccine response?
The findings demonstrate that a healthy diet could affect
vaccine effectiveness, but this doesn’t mean that people with obesity should
avoid vaccination.
As the
People can
talk with their doctors about personal risk factors that may increase
complications if they get sick with the
flu. They can also discuss any potential risks from the vaccine
itself and how effective the vaccine may be for them.
While the study won’t lead to immediate
change in clinical practice or recommendations, weight loss among individuals
who are obese is generally encouraged by healthcare professionals.
“[The
study] will need to be followed up by a human trial to see if the observation
holds up,” Yancey noted.
“If so,
then we could potentially recommend a healthy diet and weight loss in the weeks
leading up to vaccination. However, this is a general recommendation for
everyone already. So, there wouldn’t be any big changes in overall health
advice.”
Dress said
she wouldn’t change any current recommendations based on this one study in
mice, noting the following:
“There are
many health benefits to losing weight,
and [a] better response to vaccines might be one of them. But that is really
just a theory right now. I definitely would still highly promote influenza
vaccine regardless of your weight — and I would probably
recommend it even more highly in persons with obesity because we know their
risk of severe flu is higher.
So, I
wouldn’t want someone to not get vaccinated because they think the flu vaccine
won’t work for them — there is also good evidence that even if you get the flu
after being vaccinated, your risk of severe disease and death is lower. Persons
living with obesity should discuss with their doctor what their options are for
weight loss, but should still definitely get their annual flu shot.”
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