Do vaccines make people careless?

CHAPEL HILL, N.C., July 13 (UPI) -- If a vaccine offers only partial protection, U.S. researchers ask, can it increase risky behavior by giving the recipient a false sense of security?

A team at the University of North Carolina led by Noel Brewer designed a study to answer that question, and the results came out both yes and no.

The researchers conducted a random phone survey of 705 adults who lived in areas where Lyme disease is common just after the 80-percent effective Lyme vaccine became available.

They interviewed the same people again 18 months later, and compared the behavior of those who had been vaccinated to those who had not.

They discovered that, while vaccinated people were a little more careless about ordinary safety measures -- such as wearing light-colored clothing to make Lyme disease ticks visible or using tick repellent -- they did not become less cautious than unvaccinated people.

Brewer said findings from the Lyme disease vaccine survey might provide insight into another emerging issue: Whether the partially protective HPV vaccine given to young teenage girls might encourage them to engage in risky sexual behaviors.

Brewer said he thought his results indicated that they would not, and in a commentary on the article, Baruch Fischoff of Carnegie Mellon University agreed, citing a 2007 Cochrane Library review that found that girls given Plan B emergency birth control "just in case" were no more likely to engage in sex than girls who were not given the pills.

The study is published in the early online issue of the Annals of Behavioral Medicine.