Conjugated vaccine may offer improved pneumonia protection for COPD patients
MedWire News: A novel conjugated vaccine against pneumonia may offer better protection for chronic obstructive pulmonary disease (COPD) patients than the currently available vaccine, claim researchers.
The US Centers for Disease Control currently recommend that all adults with lung disease receive the 23-valent pneumococcal polysaccharide vaccine (PPSV23) to protect against exacerbations caused by infection.
However, Mark Dransfield (University of Alabama, Birmingham, USA) and colleagues explain: “Debate exists about the immunogenicity and protective efficacy of antibodies produced by the PPSV23 vaccine in COPD.”
To investigate whether a vaccine called 7-valent diphtheria-conjugated pneumococcal polysaccharide vaccine (PCV7) induces a more robust immune response than PPSV23 in COPD patients, the team studied 120 adults with the lung disease who were aged over 40 years with a smoking history of at least 10 pack–years.
“Conjugated vaccines were originally intended for young children who respond poorly to polysaccharide antigens,” said Dransfield. “We wanted to see whether they could have a similar effect in the COPD patient population in whom immune responses may also be blunted.”
In total, 63 patients were assigned to receive the PPSV23 vaccine and 57 to receive the PCV7 vaccine. Serotype-specific immunoglobulin (Ig)G concentrations and functional antibody activity – reported as an opsonization killing index (OPK) – were assessed 1 month after vaccination in both groups.
Results showed that the PCV7 vaccine produced superior immune responses on several measures of immunogenicity compared with the PPSV23 vaccine. Indeed, post-vaccination serotype-specific IgG levels were significantly higher in the PCV7 group than in the PPSV23 group for five of the seven serotypes tested.
Furthermore, blood drawn from patients who received the PCV7 vaccine had a significantly higher OPK than that drawn from patients who received the PPSV23 vaccine for four of the seven serotypes tested.
However, older age and prior vaccination with PPSV23 appeared to reduce the efficacy of the PCV7 vaccine, the researchers note in the American Journal of Respiratory and Critical Care Medicine.
They conclude: “We have shown that PCV7 induces a superior immune response to PPSV23 in COPD at 1 month post-vaccination. Both vaccines elicit responses comparable to those previously observed in healthy elderly patients.”
Dransfield added: “We believe our data provide the rationale for further study of the clinical efficacy of protein-conjugate pneumococcal vaccines in the high-risk COPD population.”
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By Mark Cowen