These findings provide evidence to explain a new phenomenon was first recognized in H1N1 flu outbreak of 2009, namely obesity associated with disruption of the immune response to influenza vaccination in humans.
The researchers studied patients who had been given inactivated influenza vaccine in late 2009 at a clinic of University of North Carolina. The vaccine is given flu vaccine for the autumn and winter regular.
Although all patients developed antibodies against the flu virus since the first month after vaccination, antibody levels in the blood decreased more rapidly in obese persons from time to time.
About 50 percent of obese study participants with antibody levels decreased fourfold during the 12 months since the first month of vaccination. While participants with healthy weight numbers are not up to 25 percent.
"These results show that people who are obese are more likely to experience flu disease after exposure to the flu virus than people with healthy weight," said Melinda Beck, Ph.D., associate professor and chair of nutrition at the University of North Carolina Gillings School of Global Public Health.
"Previous studies have suggested the possibility of obesity can impair the body's ability to fight the flu virus. These new findings seem to provide reasons why obese people are more susceptible to illness during the influenza pandemic of H1N1 flu virus than people with healthy weight," said Beck.
The review, released on the official site of University of North Carolina School of Medicine, Wednesday (26/10/2011) reported that the influenza vaccine antibody levels decreased significantly in the obese than in individuals with a healthy weight.
Moreover, the response of white blood cells are most important in the immune system known as CD8 + T cells were damaged in people who are obese.
"When vaccination fails to prevent flu infection, the patient must rely on his CD8 + T cells to limit the spread and severity of infection. If antibody levels are not maintained from time to time, and CD8 + T cell function impaired, people with obesity will have a risk greater fall ill from influenza, "said Patricia Sheridan, PhD, assistant professor of nutrition University of North Carolina School of Medicine.
In 2005, Beck and his colleagues reported that obesity in mice impairs the ability of the body fight viral infections and increased risk of death compared with lean mice with the same infection. The mortality rate is higher in obese rats, amounting to 25%. While in lean mice, none of which died.
In 2010, Beck and his team showed that obesity appears to limit the ability of mice to develop immunity to influenza. He suggested that vaccination does not seem effective for the obese and overweight.
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