Influenza vaccination and warfarin anticoagulation: a comparison of subcutaneous and intramuscular routes of administration in elderly men.
OBJECTIVE
To determine if subcutaneous administration of influenza vaccine is as immunogenic as the intramuscular route, and to evaluate the frequency of local adverse events associated with both routes in elderly anticoagulated men.


METHODS
Single-blind, prospective study of consecutively enrolled subjects.


METHODS
Ambulatory clinic at a university-affiliated Veterans Affairs medical center.


METHODS
Twenty-six men age 60 years or older, receiving therapeutic dosages of warfarin.


METHODS
Subjects were randomized to receive either intramuscular or subcutaneous injection of a standard trivalent influenza vaccine.


RESULTS
Serum antibody titers to the vaccine's components were measured at baseline, and 6 weeks and 4 months after vaccination. Both routes of administration induced comparable serum antibody titers. There were no differences in adverse events at administration sites between routes of administration.


CONCLUSIONS
Elderly individuals are able to mount an immune response to influenza vaccine and produce antibody concentrations deemed protective. The routes of administration are similarly effective at inducing an immune response. The intramuscular route in anticoagulated elderly men does not commonly result in local bleeding complications.
Delafuente
J C
JC
Department of Pharmacy Practice, College of Pharmacy, University of Florida, Gainesville 32610-0486, USA.
Davis
J A
JA
Meuleman
J R
JR
Jones
R A
RA
D000279:Administration, Cutaneous; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood; D000925:Anticoagulants / Q000009:adverse effects / Q000627:therapeutic use*; D006470:Hemorrhage / Q000517:prevention & control; D006801:Humans; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology; D007273:Injections, Intramuscular / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014611:Vaccination / Q000009:adverse effects / Q000379:methods*; D014859:Warfarin / Q000009:adverse effects / Q000627:therapeutic use*
D000906:Antibodies; D000925:Anticoagulants; D007252:Influenza Vaccines; D014859:Warfarin