WASHINGTON — The 7-valent pneumococcal conjugate vaccine (PCV7) has prevented about 210,000 cases of invasive pneumococcal disease and 14,000 disease-related deaths in the United States since its introduction 7 years ago, according to data from the Centers for Disease Control and Prevention in Atlanta.
“This far into our program, the effects have been very sustainable,” said Dr. Cynthia Whitney of the Centers for Disease Control and Prevention, adding that overall disease rates dropped after vaccination and have remained stable since 2002.
Dr. Whitney presented data based on a surveillance population of 18.5 million people at the jointly held annual Interscience Conference on Antimicrobial Agents and Chemotherapy and the annual meeting of the Infectious Diseases Society of America.
From 1998 to 2007, she and her colleagues identified cases of laboratory-confirmed invasive pneumococcal disease (IPD) through eight U.S. sites that continuously participated in Active Bacterial Core surveillance, a nationwide program to track vaccination rates and collect isolates.
Children younger than age 5 years were the target age group for disease reduction with PCV7. The disease rates in this age group dropped from 100 cases per 100,000 at a baseline measurement in 1998 to about 25 cases per 100,000 in 2007. For disease caused by PCV7 serotypes (4, 6B, 9V, 14, 18C, 19F, 23F), the rate was less than a single case per 100,000 in 2007, she added.
The PCV7 rates have continued to drop, but the overall rates have flattened in the last few years. An increase in disease caused by non-PCV7 serotypes has contributed to the plateau effect, Dr. Whitney explained. In particular, the incidence of disease caused by serotype 19A has increased consistently since 2002.
Although vaccine-type disease decreased and 19A disease increased, these changes occurred mostly between 2002 and 2006, and the rates in 2006 and 2007 were similar. “It may be that now, 8 years into the vaccine program, we are finally reaching a steady state for some of these changes,” Dr. Whitney observed.
The benefits of PCV7 extend to all ages, she emphasized. “Very few people older than 5 years have received the vaccine, so the herd effect has been important.”
Data from 2007 show some disease in all age groups. But only 7% of 2007 cases were caused by PCV7 serotypes. By contrast, 20% were caused by 19A, and 58% were caused by serotypes that are included in the PCV13 vaccine (1, 3, 5, 6A, 7F, 19A). The PCV13 vaccine data are under review, and the vaccine may be licensed in the United States next year.
“Recommending the 7-valent vaccine to a small part of the population, kids younger than 2 years, has led to substantial community protection,” said Dr. Whitney.
Ideally, the upcoming PCV13 vaccine will have an even greater impact on pneumococcal disease, she said.
Dr. Whitney said she had no conflicts of interest to disclose.
Elsevier Global Medical News