Pneumonia: combined live and inactivated influenza A vaccines decreased cases.

Clinical bottom line (level 1b)

  1. Elderly patients who were given combined live and inactivated influenza A vaccines were less likely to have laboratory-documented influenza A during an outbreak, than those given inactivated virus alone (NNT = 12 at 3 years) .
  2. Elderly patients given a combined live and inactivated influenza A vaccine had no clear difference in adverse effects, than those given inactivated vaccine alone.
Treanor et al: Annals of Internal Medicine 1992; 117: 625-633
Expires March 2003

The study

Double-blinded ?concealed randomised trial with intention-to-treat
Setting: Three long-term care facilities, USA

732 patients (aged mean 83 years, 78% female) Patients in any of the long-term care facilities

Excluded if
  • acutely ill at time of enrollment
  • required concurrent therapy with immunosuppressive drugs
  • allergic to egg products
  • refused inactivated influenza vaccine


    • Control Group: (n = 362, 346 analysed): intranasal placebo
    Experimental Group: (n = 370, 345 analysed): intranasal vaccination with the most current cold-adapted H3N2 influenza A vaccine virus available
    All patient sreceived intramuscular trivalent inactivated subviron influnza vaccine as recommended for that year.
    99% followed for 3 years

    The evidence

    Outcome Time to outcome CEREERRRR
    (95% CI)    		ARR
    (95% CI)    		NNT
    (95% CI)
    laboratory-documented influenza A during outbreaks in institutions 3 years 24
    (14.2%)    		 9
    (5.56%)    		 61.0%
    (18.0% to 81.0%)    		 8.65%
    (2.31% to 15.0%)    		 12
    (7 to 43)
    adverse reactions 3 days 15
    (8.29%)    		 18
    (10.1%)    		 -22.0%
    (-134% to 37.0%)    		 -1.83%
    (-7.80% to 4.15%)    		 -55
    (NNT = 24 to infinity;
    NNH = 13 to infinity)

  • Vaccine protective efficacy in laboratory-documented influenza A was 60.6% (CI 18% to 82%).

    • Comments

    1. Patients participating the study during more than 1 year received a new random assignment to vaccine or placebo in each year of participation, and results of each year were considered to represent independent observations.

    Citation

    1. Treanor JJ, Mattison HR, Dumyati G, et al: Protective efficacy of combined live intranasal and inactivated influenza A virus vaccines in the elderly. Annals of Internal Medicine 1992; 117: 625-633
    Contributor: Clare Wotton and Musab Hayatli, November 1999
    Reviewer: Mitsuhiro Kamei

    Clinical Question.
    Patient residents of long-term care facilities
    Intervention or Exposure live and inactivated influenza vaccines
    Comparison inactivated influenza vaccine alone
    Outcome adverse effects and serum antibody levels