I have written a lot about health myths that many of us as health professionals believe. Here, I’d like to address some myths about influenza shots that our patients believe.
“I do not want the flu shot, since it will make me sick or give me the flu.”
This is a common reason patients will share as to why they do not want a flu shot. Frequently, I will hear about the time they did get a flu shot and shortly afterward got sick. This myth has been well studied with well-designed trials. Govaert and colleagues studied more than 1800 patients over the age of 60 who were randomly assigned to receive flu vaccine or placebo saline injection; side effects were tracked over 4 weeks. The only difference in side effects was an increased rate of local tenderness at the injection site: 17.5% in the vaccine group vs 7.3% in placebo group. There was no significant difference in systemic side effects.
Margolis et al conducted a randomized, controlled, crossover trial in 336 veterans aged 65 or older. Trial participants were randomly assigned to receive influenza vaccine followed 2 weeks later by placebo injection or placebo followed 2 weeks later by vaccine. The only significant difference after receiving vaccine compared with placebo was a sore arm. There was no difference in any other symptom.
Another interesting study looked at patients with chronic obstructive pulmonary disease who received influenza vaccine or placebo; side effects and respiratory infections were evaluated in the first week after vaccination. Local adverse reactions were noted in 27% of the vaccine group and 6% of the placebo group (P =.002). No significant difference in systemic adverse reactions was measured between the vaccine and placebo groups, and there was no difference observed in the incidence of acute respiratory infections between the vaccine and placebo groups during the first week (6.4% vs 6.3%; P = 1.0) and the first 4 weeks (24.2% vs 31.7%; P =.5) after vaccination.
“I can’t get the flu shot because I am allergic to eggs.”
For many years, patients were asked if they had an egg allergy, and if they did, they usually were told not to get influenza vaccine. This was because of the concern that potentially minute particles of egg protein could contaminate the vaccine and individuals with severe allergy could have a bad reaction. Turner and colleagues recruited 779 young people (2-18 years) with egg allergy to receive influenza vaccine. The cohort included 270 young people with previous anaphylaxis to egg. No systemic allergic reactions occurred in any participants.
Kelso reviewed 28 studies with a total of 4315 patients with egg allergy who received egg-based Influenza vaccine: included were 656 patients with a history of anaphylaxis to egg. None of these patients developed a serious reaction when they received influenza vaccine.
A 2017 joint practice parameter by the American Academy of Allergy, Asthma, and Immunology and the American College of Allergy, Asthma, and Immunology stated that all patients with egg allergy of any severity should receive inactivated influenza vaccine annually, using any age-approved brand, and there are no special waiting periods after vaccination of egg allergic patients beyond what is standard practice for any vaccine.
Pearl: Influenza vaccine can cause local discomfort but is no different from placebo in producing systemic symptoms. Individuals with a history of egg allergy can safely receive any form of influenza vaccine.