September 14, 2010 (Boston, Massachusetts) — Vaccinating children with a pneumococcal conjugate vaccine (PCV) in a Canadian government-funded program implemented in 2004 failed to reduce adult hospitalizations for pneumonia during the subsequent3 years, according to findings presented here at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy.
"The big question is how to prevent pneumonia in adults. The current polysaccharide pneumococcal vaccine [PPV] is not very effective for adults. However, the pneumococcal conjugate vaccine introduced in 2001 for children is very effective in preventing pneumococcal disease, pneumonia, and otitis media. We wanted to study whether a publicly funded PCV program implemented in Quebec in 2004 would have an indirect effect on the frequency of adult hospital admissions for all-cause pneumonia," said lead author Philippe De Wals, PhD, professor of public health at Laval University in Quebec City, Quebec.
Community-acquired pneumonia is a major public health problem in adults, resulting in hospitalization, morbidity, use of antibiotics, and even mortality, Dr. De Wals explained. Previous studies have suggested that vaccinating children could have an indirect preventive effect on adults.
"A careful analysis of data in Quebec found no indirect effect. The main implication of this study is that we have to develop new effective vaccines for adults against pneumococcal disease," he stated.
The study was based on medical records of Quebeckers 20 years or older diagnosed with pneumonia and admitted to the hospital between January 1, 1990 and December 31, 2007. A total of 211,644 hospital discharges for all-cause pneumonia were identified, representing close to 100 million person-years of observation.
As of 2007, more than 90% of children younger than 5 years of age in the program received at least 1 dose of the vaccine, almost 80% received at least 2 doses, and about 50% received at least 3 doses. However, the frequency of hospital admissions for those 20 to 39 years of age and for those 40 to 59 years of age remained stable over time. Patients 60 to 79 years of age had increased rates of hospitalization after 1993 that persisted to 2007.
"We really have no satisfactory explanation for the upward break in baseline observed in elderly patients from 1993 on," Dr. De Wals stated. He speculated that comorbidities in the elderly could have aggravated the severity of pneumonia, leading to more frequent hospitalizations in this age group.
An improved version of PCV (PCV-13) is now used in the United States for children. It remains to be seen whether this new vaccine has an indirect beneficial effect for adults. A more interesting strategy would be to vaccinate adults with this new vaccine; more studies are needed to support this idea.
New Pediatric Vaccine May Affect Adults
"I fully support the wish to develop better pneumococcal vaccines for children and adults." said Sean P. Elliott, MD, professor of clinical pediatrics at the University of Arizona in Tucson.
Prevnar 13 — a new licensed PCV that covers 6 more types of bacteria than its predecessor Prevnar 7 — was approved by the US Food and Drug Administration for use in children in February 2010. The new vaccine covers strains of pneumococcus that are particularly invasive in children, Dr. Elliott continued.
"Unlike Prevnar 7, the new vaccine covers pneumococcal type 19A, which is the organism responsible for many of our current cases of pneumonia, meningitis, and mastoiditis. The new vaccine, when used in children, should have a bigger impact on adults," Dr. Elliott stated.
Dr. De Wals reports receiving financial support from vaccine manufacturers, including Pfizer, GlaxoSmithKline, Novartis, and Sanofi. Dr. Elliot has disclosed no relevant financial relationships.
50th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC): Abstract G1-187. Presented September 12, 2010.
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Cite this: Pneumococcal Vaccine in Childhood Does Not Reduce Adult Hospitalizations for Pneumonia - Medscape - Sep 14, 2010.