CAPE TOWN, South Africa — The 13-valent pneumococcal conjugate vaccine (PCV-13) offers moderate protection against the most common forms of pneumococcal community-acquired pneumonia in healthy elderly people, a large prospective trial shows.
"Pneumococcal conjugate vaccines are effective in preventing invasive pneumococcal disease and pneumonia in children, but vaccine efficacy has not been investigated in adults older than 65," said Marc Bonten, MD, professor of molecular epidemiology of infectious disease at the Julius Center for Health Sciences and Primary Care in Utrecht, the Netherlands.
"A clear medical need exists among adults to prevent pneumococcal disease, including pneumococcal community-acquired pneumonia. Whether the benefit we demonstrated in individuals translates into an overall public health benefit needs further analyses," he said.
The study results were presented here at the 16th International Congress on Infectious Diseases.
The CAPiTA Study
The Community-Acquired Pneumonia Immunization Trial in Adults (CAPiTA) is one of the largest prospective vaccine efficacy trials carried out in adults. A total of 84,496 adults 65 years and older were randomized to receive either PCV-13 or placebo.
Residents of nursing homes or long-term care facilities, people who had received previous pneumococcal vaccination, and those who were immunosuppressed were excluded from the analysis.
The primary goal of CAPiTA was the prevention of a first episode of vaccine-type pneumococcal community-acquired pneumonia. Secondary goals were the prevention of a first episode of nonbacteremic/noninvasive vaccine-type pneumococcal community-acquired pneumonia and of vaccine-type invasive pneumococcal disease.
Subjects were enrolled at community-based sites and during home visits. Pneumococcal pneumonia and invasive pneumococcal disease were confirmed at 58 participating hospitals in the areas of enrollment.
A serotype-specific urinary antigen detection assay, developed specifically for the study by its sponsor, Pfizer, was used to identify episodes of vaccine-type community-acquired pneumonia. This enabled investigators to detect PCV-13 serotypes with a high degree of accuracy in the urine of patients who developed pneumonia, Dr. Bonten explained.
PCV-13 was 45.5% effective at preventing a first episode of vaccine-type pneumococcal pneumonia, compared with placebo. It was also 45.0% effective at preventing a first episode of nonbacteremic/noninvasive vaccine-type pneumococcal pneumonia and 75.0% effective at preventing vaccine-type invasive pneumococcal disease.
All results were based on a per protocol analysis.
Results from a modified intent-to-treat analysis were slightly less robust than per protocol results, said Dr. Bonten. Relative to placebo, PCV-13 prevented 37.7% of first of vaccine-type pneumococcal pneumonia, 41.0% of first episodes of nonbacteremic/noninvasive vaccine-type pneumococcal pneumonia, and 75.7% of first episodes of vaccine-type invasive pneumococcal disease.
Safety Issues
"There were no safety issues with this vaccine," Dr. Bonten reported. The incidence of serious adverse events was similar in the 2 groups, as were mortality rates.
As expected, vaccine recipients experienced more local reactions, including redness, pain, and swelling in the arm, but the incidence of severe local reactions was very low and similar in the 2 groups.
Shabir Madhi, MD, PhD, professor of vaccinology at the University of Witwatersrand in South Africa, expressed reservations about the overall benefit that PCV-13 might offer the elderly, at least from a public health perspective.
"I can't see many governments paying for this vaccine because we're looking at very large numbers in terms of the population who would be eligible for it," Dr. Madhi told by Medscape Medical News.
In the United States, the incidence of invasive pneumococcal disease in adults 65 and older declined by more than 90% after the introduction of the 7-valent PCV in the pediatric population.
PCV-13 has 3 key serotypes that are not in the 7-valent PCV: serotypes 1, 3 and 7F. "These 3 serotypes do not commonly colonize children, so we're not sure whether the 13-valent conjugate vaccine given to children will actually reduce transmission of these 3 serotypes in the general population," Dr. Madhi explained.
A 23-valent pneumococcal polysaccharide vaccine (PPV23) is available for the elderly to prevent pneumococcal infection. According to a recent Cochrane analysis, PPV23 prevents approximately three quarters of invasive pneumococcal disease in the elderly (Cochrane Database Syst Rev. 2013;1:CD000422).
However, as Dr. Madhi pointed out, the great majority of pneumococcal disease is nonbacteremic pneumonia. Invasive pneumococcal disease occurs rarely, and probably accounts for less than 0.5% of all pneumococcal disease.
PPV23 "has not been shown to be efficacious for pneumonia, so vaccine efficacy in people over the age of 65 is almost nonexistent," he explained. "There is a need for a vaccine in the elderly, but whether that need exists in the context of adequate childhood immunization is an open question."
The study was funded by Pfizer. Dr. Bonten has disclosed no relevant financial relationships.
16th International Congress on Infectious Diseases (ICID): Abstract 09.004. Presented April 3, 2014.
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Cite this: Moderate Pneumonia Protection With PCV-13 in the Elderly - Medscape - Apr 04, 2014.
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