A second booster shot against the returning menace of whooping cough (search) won government approval Friday — this one for adults as well as teenagers.

The cough so strong it can break a rib was once thought to be history thanks to effective vaccination of babies and toddlers. But protection from those early-in-life shots wears off, and outbreaks among adolescents and adults have increased dramatically. While older patients usually recover, whooping cough can cause weeks of misery — and they can easily spread the illness to not-yet-vaccinated infants, who are at risk of dying from the bacterial infection.

A month ago, the Food and Drug Administration (search) approved the first booster shot for adolescents, GlaxoSmithKline's Boostrix (search), for 10- to 18-year-olds.

Friday, rival Sanofi-Aventis won FDA approval for its whooping cough booster, Adacel (search), for people ages 11 to 64.

Both combine protection against whooping cough, also called pertussis, in the same shot as an already standard booster against tetanus and diphtheria. Children are supposed to get that so-called Td booster sometime between ages 11 and 18, and adults are encouraged to get a tetanus booster every 10 years.

While FDA approval allows the new combination shot to be sold, doctors usually wait to administer new inoculations until they're formally added to the nation's official vaccination schedule — a step that also ensures insurance coverage. Later this month, an advisory committee of the Centers for Disease Control and Prevention is expected to add the adolescent booster to that list.

How quickly adults will be urged to get a pertussis booster — and how often — is unclear. But CDC officials expect that first targets would be day care providers, parents of infants and health workers, because keeping them well would in turn protect infants.

Adacel will cost $33.50, roughly $15 more than the tetanus-diphtheria booster alone, said a spokesman for Sanofi-Aventis' vaccine division.

The CDC received 18,957 reports of whooping cough last year, up from 11,647 in 2003 and just 1,707 in 1980. Experts say that's an underestimate, because milder cases frequently go undiagnosed in teens and adults.

Adacel's side effects were comparable to those of tetanus boosters, including injection-site pain and low fevers, although adolescents reported those complaints more often with Adacel, the FDA said.