How Journals Can Twist and Manipulate Vaccine Research
December 17, 2009
Children and the elderly are the two age groups that appear to have the most complications following an influenza infection.
Influenza has a viral origin and often results in an acute respiratory illness affecting the lower or upper parts respiratory tract, or both. Viruses are mainly of two subtypes (A or B) and spread periodically during the autumn-winter months. Many other viruses however, can also cause illness of the respiratory tract.
Public health efforts to contain the virus rely mainly on widespread vaccination. Recent policy from several internationally-recognized institutions recommends immunization of healthy children from the age of six months and up.
In their 2008 update of a review done in 2006, Cochrane authors found a marked difference between vaccine “efficacy” versus their effectiveness.
Although these two terms are oftentimes used interchangeably in daily conversation, when used in a medical context they confer two different meanings.
“Efficacy” means the extent to which a specific intervention produces a therapeutic effect, or a beneficial result under ideal conditions. The protective efficacy of a vaccine is determined on what is called “antibody titer”.
A simplified explanation is that the antibody titer is a measurement of the amount of antibodies produced in your body that recognize a particular antigen (virus).
“Effectiveness,” on the other hand, shows the intervention’s capacity for producing the intended or expected result. In the case of a flu vaccine, the intended result would be considered its capacity to prevent influenza illness.
In children over the age of 2, nasal spray vaccines made from weakened live viruses had an:
- Efficacy of 82 percent compared with placebo or no intervention
- Effectiveness of 33 percent
In children over the age of 2, inactivated (injectable) vaccines had an:
- Efficacy of 59 percent compared to live vaccines
- Effectiveness of 36 percent
In children under 2, the efficacy of inactivated vaccine was similar to placebo.