I came across this report today, which concerns childhood vaccination against influenza. Normally, vaccines contain three strains of flu virus (trivalent vaccine). In theory, a quadrivalent (four-strain) vaccine might provide better protection again flu. In the study referred to in the report, children and adolescents were randomised to receive either a quadrivalent vaccine or one of two trivalent vaccines.
The vaccines were administered as a nasal spray. Immune responses to the vaccine were assessed and found to be similar across all three vaccines. Safety was said to be comparable except that the quadrivalent vaccine produced more fever in children aged 2-8 [1].
You can see from the report that one of the authors of the study, Dr Robert Belshe (professor of infectious diseases at Saint Louis University School of Medicine) is quoted as saying:
“The bottom line is adding another strain to make a quadrivalent vaccine improves our ability to protect against flu and doesn’t reduce the body’s immune response to the other strains,” and “It should bring us better protection because there’s less guess work than in the standard trivalent vaccine.”
Lots of pro-vaccine rhetoric here, but let’s examine the facts for a moment.
First of all, this study was not designed to assess the effectiveness of the different vaccines. It looked at immune responses and safety. Professor Belshe’s assertion that “The bottom line is adding another strain to make a quadrivalent vaccine improves our ability to protect against flu” is speculative, not something that has been demonstrated at all.
But another deficiency of Professor Belshe’s study is this: it contained no placebo group. This seems like a glaring omission to me. How can we tell from such a study whether the effects the vaccines had was real and/or a placebo-generated response? The answer is we can’t.
Mind you, we should perhaps not be too surprised. After all, there for some reason seems to be quite a lot of resistance in the scientific and medical community to subject vaccines to randomised placebo-controlled trials, despite the fact that they are easy to do and would tell us the true effectiveness of vaccines.
References:
1. Block SL, et al. The Immunogenicity and Safety of a Quadrivalent Live Attenuated Influenza Vaccine in Children. Pediatric Infectious Disease Journal epub 29 March 2012
