Convincing patients of the merits of human papillomavirus (HPV) vaccines has proved a tricky task for Merck ($MRK) and GlaxoSmithKline ($GSK). The first product to market in the U.S., Merck's Gardasil, opened with sales of $1.5 billion in 2007, but then fell away, only surpassing the initial high last year.
Strong uptake shortly after approval partly accounts for the 2007 peak and subsequent lull, but Gardasil--and GSK's Cervarix--have also been hit by anti-vaccine sentiment. The breadth and depth of this sentiment was shown by a new paper published in Pediatrics. Researchers looked at data from a U.S. national survey and found a rising proportion of parents are choosing against vaccinating their children for HPV.
In 2008, 40% of parents had no plans to give their children HPV vaccines. In 2010 the figure rose to 44%. The uptick is attributable to growing concerns among parents about the safety of HPV vaccines. 'Safety concerns/side effects' has increased from being a reason for not vaccinating for one in 20 parents in 2008, to one in 6 in 2010. Now only 'not needed or not necessary' is a more common reason.
The rise in safety concerns comes despite growing evidence HPV vaccines have relatively few side effects. "Safety concerns have always risen to the top of the pile, in terms of being one of the main reasons people don't get vaccinated, which is unfortunate because this is one of the most well-studied vaccines in terms of safety and is extremely safe," Amanda Dempsey from the University of Colorado Denver told Reuters.
Despite more than two-fifths of parents deciding against having their children vaccinated, the proportion protected against HPV rose to one-third, up from 16% in 2008. But Dempsey said other vaccines--such as Tdap (tetanus, diphtheria and pertussis)--were adopted faster. The discrepancy reflects HPV-specific concerns that must be addressed if vaccination levels are to push much past 50%, researchers write in Pediatrics.