Manufacturer’s Inserts and efficacy statements:
Fluarix-ranges between 56-80.5%
FluMist (live virus)– (Regardless of match)
All strains- ranged between 45.4-62.9%
A/H1N1- ranged between 67-97.4%
A/H3N2- ranged between 70.6-85.7%
B- averaged 16.1%, ranged between (-7.7)-34.7%
* This systematic review states:
The yearly recommended vaccines had low effectiveness against clinical influenza cases: 15%(95% CI 8% to 21%) and 25% (95% CI 13% to 35%) respectively. Overall the percentage of participants experiencing clinical influenza decreased by 6%. Use of the vaccine significantly reduced time off work but only by 0.16 days for each influenza episode (95% CI 0.04 to 0.29 days); Analysis of vaccines matching the circulating strain gave higher estimates of efficacy, whilst inclusion of all other vaccines reduced the efficacy.
Influenza vaccines are effective in reducing serologically confirmed cases of influenza. However, they are not as effective in reducing cases of clinical influenza and number of working days lost. Universal immunisation of healthy adults is not supported by the results of this review.
In children under 2 years inactivated vaccines had the same field efficacy as placebo,8 and in healthy people under 65 vaccination did not affect hospital stay, time off work, or death from influenza and its complications.9
Public policy worldwide recommends the use of
inactivated influenza vaccines to prevent seasonal
Because viral circulation and antigenic match vary
each year and non-randomised studies
predominate, systematic reviews of large datasets
from several decades provide the best
information on vaccine performance.
Evidence from systematic reviews shows that
inactivated vaccines have little or no effect on the
Most studies are of poor methodological quality
and the impact of confounders is high.
Little comparative evidence exists on the safety of
Reasons for the current gap between policy and
evidence are unclear, but given the huge
resources involved, a re-evaluation should be
The optimistic and confident tone of some predictions
of viral circulation and of the impact of
inactivated vaccines, which are at odds with the
evidence, is striking. The reasons are probably complex
and may involve “a messy blend of truth conflicts and
conflicts of interest making it difficult to separate
factual disputes from value disputes”22 or a manifestation
of optimism bias (an unwarranted belief in the
efficacy of interventions).23
Whatever the reasons, it is a sobering thought that
Archie Cochrane’s 1972 statement that we should use
what has been tested and found to reach its objectives
is as revolutionary now as it was then.