Current issues of ACP Journal Club are published in Annals of Internal Medicine


Therapeutics

Influenza vaccine caused few adverse reactions in elderly patients

ACP J Club. 1991 Jan-Feb;114:14. doi:10.7326/ACPJC-1991-114-1-014


Source Citation

Margolis KL, Nichol KL, Poland GA, Pluhar RE. Frequency of adverse reactions to influenza vaccine in the elderly: a randomized, placebo-controlled trial. JAMA. 1990 Sep 5;264:1139-41. [PubMed ID: 2200894]


Abstract

Objective

To assess the frequency and type of adverse reactions to influenza vaccine in persons > 65 years of age.

Design

Randomized, double-blind, placebo-controlled, crossover study of influenza vaccine compared with saline.

Setting

Outpatient department, Minneapolis Department of Veterans Affairs Medical Center in the United States.

Participants

The first 437 persons who responded to a mailed invitation were asked to participate. 354 persons joined the study and were randomized; 336 (94.9%) completed the study. The mean age of the participants was 70.6 years, and 95.5% were men.

Intervention

Sequence 1 consisted of a 0.5-mL intramuscular injection of 1988-1989 trivalent split-antigen influenza vaccine injected into the right or left deltoid according to a randomization schedule. Two weeks later a placebo saline injection was given in the opposite arm. Sequence 2 reversed the order of these injections.

Main oucome measures

A week after each injection (vaccine or placebo), each patient was given a structured telephone interview, that included inquiries about symptoms, general health, and limitations on normal activities produced by the injection. Symptoms reported included fever, cough, nausea, and headache.

Main results

A pilot study had indicated a "treatment effect" of 14.2% vaccine-associated symptoms compared with a background of 8.7% symptoms. It was calculated that 350 participants were needed to detect this effect with 90% power. No difference was found between the post-vaccination and the post-placebo interviews in number or severity of symptoms, general health, or limitation on normal activities. Arm soreness, however, was reported more often after vaccination (20.1 % vs 4.9% after placebo, P < 0.001). 1 or more symptoms, excluding arm soreness, were reported by 27.7% of the participants after vaccination and by 22.9% after the placebo injection (P = 0.21). The participants were asked at the end of the trial to identify the sequence of injections; 64.6% were correct (kappa = 0.27, which indicates only poor to fair agreement beyond chance).

Conclusion

Other than arm soreness, influenza vaccine was not shown to produce more numerous, severe, or long-lasting symptoms, general ill health, or limitation on activities than placebo, based on reports from elderly, participants who were mostly men.

Sources of funding: Minnesota Medical Foundation and Wyeth-Ayerst Laboratories (vaccine supplier).

Address for article reprint: Dr. K.L. Margolis, Department of Medicine, Hennepin County Medical Center, 701 Park Avenue South, Minneapolis, MN 55415, USA.


Commentary

Influenza endures as one of the most important public-health problems in developed countries. Less than a quarter of people at risk for serious complications are immunized each year. Although earlier whole-cell vaccines were associated with a high incidence of local and systemic complications, Margolis and colleagues, in this well-designed, carefully executed, and precisely reported investigation, have shown that the only complication of split-virus vaccine is soreness of the arm, which was reported by only 20% of the participants after active vaccination.

The only remaining reasonable contraindication to the use of influenza vaccine is hypersensitivity to eggs. We may now recommend vaccination with confidence to our patients and communicate these convictions to the media so that the safety of vaccines can be made clear to the general public.

Stephen R. Jones, MD
Good Samaritan Hospital & Medical CenterPortland, Oregon, USA