Any medication involves a balancing of risk and benefit. In areas where there is an unmet need, a little more risk might be acceptable. But the waters get muddy when two treatments, one offering better results but greater risks, are available for patients.
A growing body of evidence shows this is the case with whooping cough, also known as pertussis. In the 1990s, whole-cell pertussis vaccines developed in the 1940s were phased out amid safety fears. Acellular vaccines from GlaxoSmithKline ($GSK) and Sanofi ($SNY) took their place, but since then, incidence of whooping cough has increased. Now a study by Kaiser Permanente has pinned the resurgence of whooping cough on the reduced effectiveness of the acellular vaccine.
The phased withdrawal of whole-cell vaccines in the 1990s means some children were given the acellular vaccine for all 5 of their pertussis jabs, while others received the older shots for their first four injections. In the 2010-2011 California whooping cough outbreak, kids who received the acellular vaccine for all 5 of their shots were 6 times more likely to contract pertussis, a paper in Pediatrics found. For each whole-cell jab replaced by an acellular variant, the risk of developing whooping cough increased by 40%. The finding adds to data published in Pediatrics in March that also suggested the acellular vaccine is failing to protect some kids.
But what authorities do with this knowledge is an unresolved question. The whole-cell shot was dropped because it triggered adverse events in some babies. And as pediatric infectious diseases specialist Dr. H. Cody Meissner told Reuters Health, "It's very hard to recommend a vaccine that is known to be associated with more side effects than another vaccine that's safer, even though the first vaccine gives better protection."