A pneumonia vaccine licensed in 2000 for young U.S. children has reduced the spread of the contagious illness and cut by thousands the number of adult cases and deaths, researchers said on Tuesday.
Crediting the vaccine, there were an estimated 12,500 fewer illness cases and 1,100 fewer deaths among Americans older than 50 in 2002 and 2003, said study author Catherine Lexau of the Minnesota Department of Health in St. Paul.
Pneumonia and complications from the flu kill nearly 64,000 Americans each year, many of them elderly, and millions get an annual shot of flu vaccine to try to prepare their immune systems to fight off illness.
Marketed as Prevnar by Wyeth, pneumococcal 7-valent conjugate vaccine (PCV-7) protects infants and toddlers against some but not all bacteria strains that can cause pneumonia. It is supposed to be given in four doses up to age 15 months.
The U.S. Centers for Disease Control and Prevention has previously said that among children aged 2 and younger the number of pneumonia cases related to strains contained in the vaccine have dropped by 78 percent to 34 per 100,000 children.
The study reported in the Journal of the American Medical Association said pneumonia cases among adults over age 50 dropped 28 percent to 29 cases per 100,000 people in 2002-2003 after the vaccine was introduced, compared to 41 per 100,000 in 1998-1999.
"Several factors support the hypothesis that the declines in invasive disease reported here likely occurred because of decreased community transmission of vaccine-type pneumococci from young children, many of whom have received PCV-7," Lexau wrote.
Her analysis was based on 18 million Americans living in eight geographic regions, but she cautioned the vaccine may have less impact in other areas where other pneumococcal strains may be prevalent.