Fever, fatigue, pain … Some people find it difficult to take injections of flu shots and suffer from many side effects. To better understand the causes of these reactions, immunology researchers at King’s College London (United Kingdom) are interested in the biological responses generated by the administration of a vaccine. They measured the reactions of the immune system in 178 participants aged 18 to 65 and in good health after injection of the 2009 influenza A (H1N1) vaccine containing an adjuvant. Their study is published in the journal Nature Immunology.
The vaccine changes the flow of white blood cells
Within 24 hours of injecting this vaccine, researchers recorded changes in the frequency of circulation of lymphocytes, white blood cells playing a key role in the body’s immune function. They also noted changes in gene expression and variations in protein levels. Age appears to play a role in these reactions since the biological response to the vaccine was significantly different in participants over 35 years of age. “We are studying the mechanisms by which lymphocytes are activated within 24 hours of vaccination when these immune defense cells should not be activated until five to seven days after injection, according to the textbooks.“Adrian Hayday, lead author of the study, told AFP.this may provide clues to improve vaccine formulation“.
Predict the risk of side effects with a blood test
Of the total number of participants, 20% declared adverse reactions (from which they recovered in one to seven days). In these people, scientists have noticed an atypical biological profile pre-existing to vaccination. This profile could eventually be identified by a simple blood test to anticipate undesirable effects linked to an exacerbated reaction of the immune system following the injection of a vaccine of this type.
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