Symptom Vaccine (%) Placebo (%) Feverish 5.7 4.2 Malaise 7.2 6.3 Myalgia 4.8 4.2 Headache 6.9 7.6 Nausea 4.5 2.4 Sore arm 20.1 4.9 Influenza vaccine post-injection symptoms in elderly subjects Soreness at the site of injection isthe only common side effect Margolis KL et al. JAMA 1990; 264: 1139–41.
Safety issues with influenza vaccines • Influenza vaccines have an excellent safety profile • Influenza vaccination is contraindicated if the patient has: • An allergy to any constituent • An acute febrile illness • Previous Guillain-Barré syndrome (GBS) within6 weeks of vaccination • Concerns have been raised about: • The sporadic association of GBS with influenza vaccination (rare: < 1 per million vaccine doses) • Exacerbations of asthma (may occur, but are uncommonand rarely severe) • Generally, the benefits of vaccination outweigh the risks
GBS and influenza vaccination • An unexplained increase in the risk of GBS occurred among recipients of the swine influenza vaccine in the USA in 1976–77 • From July 1990–June 2003, the US Vaccine Adverse Events Reporting System (VAERS) received 501 reports of GBS following influenza vaccination in adults • The median onset interval (13 days) was longer than thatof non-GBS reports of adverse events after influenza vaccine(1 day) • The annual reporting rate decreased 4-fold from a highof0.17 per 100,000 vaccinees in 1993–1994 to 0.04 in 2002–2003 • A GBS diagnosis was confirmed in 82% of reports • Preceding illness within 4 weeks of vaccination was identified in 24% of reported cases Haber P et al. JAMA 2004; 292: 2478–81.
Influenza vaccination and exacerbations of asthma • The pooled results of two trials involving 2306 individuals with asthma did not demonstrate a significant increase in asthma exacerbations in the 2 weeks following influenza vaccination • A recent study of 696 children with asthma did not demonstrate a significant reduction in influenza-related asthma exacerbations Cates CJ et al. Cochrane Database Syst Rev 2004; 2: CD000364.
After influenza vaccination What we need to advise patients: • Take paracetamol as advised (paracetamol priorto influenza vaccination can berecommendedfor children) • Drink extra fluids • Place a cool flannel at the site of the injection • Advise them to contact you if they haveanyunexpected reaction to influenza vaccination orif they are at all concerned • Most people generally tolerate influenza vaccine well . National Influenza Immunisation Strategy Group.
By courtesy of APACIAsia-Pacific Advisory Committee on influenzawww.apaci-flu.com