Kidney transplant patients vaccinated against Streptococcus pneumoniae appear to be protected against pneumococcal infection for at least 15 months, research shows.
Up to this time point, the clinically stable kidney transplant patients retained 77% of the antibody concentrations they had at month 1.
However, given the decline in antibodies, the "results support the need for revaccination," state Monika Lindemann (University Hospital Essen, Germany) and colleagues in Transplantation.
At this juncture, it is not yet clear what time point - 2, 3, 4, or 5 years - is best for revaccination, add the researchers.
Vaccination against S. pneumoniae is recommended for patients with immunodeficiency or chronic disease. Previous studies by the group have shown that 1 month after pneumococcal vaccination, clinically stable kidney transplant patients had almost normal concentrations of pneumococcal antibodies.
In the present study, the researchers defined the long-term efficacy of pneumococcal vaccination in 49 kidney transplant recipients.
The total antibody concentration increased from a median of 18.2 mg/L prior to vaccination to 53.6 mg/L at 1 month and 41.3 mg/L at 15 months.
Antibodies against 14 pneumococcal serotypes were determined before vaccination, at which point eight were recognized. At 1 and 15 months, 13 and 11 serotypes were recognized. Compared with the first month, the total antibody concentration and the number of serotypes recognized significantly declined.
However, the decline was less in younger patients, women, in patients receiving cyclosporine A versus tacrolimus, and in patients with better kidney function.
Overall, the decline in antibody concentrations appears to be more rapid than the decline in healthy controls, note Lindemann and colleagues.
Previous findings "imply that the decline in antibodies in kidney transplant recipients at month 15 would be comparable with the decline five to six years after vaccination in healthy controls," they state.
In terms of the clinical implications, Lindemann et al note it is recommended that adults with immunosuppression or chronic disease be revaccinated against pneumococci after 5 years, but their data suggest a shorter interval might be superior for protective antibodies.
However, until further studies are carried out to determine the optimal revaccination time period, they recommend revaccination against pneumococci after 5 years.
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