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When the influenza A (H1N1) virus swept around the world in spring 2009, infection was presumed to be more common in immunosuppressed patients, such as those who have had a kidney transplant. Later that year, the International Societies of Transplantation recommended that transplant recipients receive at least one dose of the H1N1 vaccine, although there was no information on the efficacy of the vaccine in that population.
Marta Crespo, MD, and Julio Pascual, MD, PhD (Parc de Salut Mer, Barcelona, Spain), have now evaluated the efficacy of the H1N1 vaccine in patients who had received a kidney transplant, as well as those on hemodialysis. They found the vaccine was safe in kidney patients, but using a single dose of the vaccine produced a poor response in patients, according to a study recently published in the Clinical Journal of American Society of Nephrology.
Included in the study were 79 kidney transplant patients, 48 hemodialysis patients, and 15 healthcare workers who had normal kidney function. All who were vaccinated received one dose of the vaccine; blood samples were tested for antibodies against the virus before vaccination andÂ eight weeks after.
Of the 96 people (including controls) who received the vaccine, 43.7 percentÂ (42/96) developed antibodies (seroconverted). That included 41.8 percentÂ of those in the kidney transplant group, 33.3 percentÂ of those on hemodialysis, and 81.8 percentÂ of the healthy controls. The healthy control group had a significantly better response than the other two groups; there was no significant difference in response between the other two groups. Overall, younger people were more likely to seroconvert. In the transplant group, patients who had more time since transplantation were more likely to seroconvert than those with recent transplants, and in the hemodialysis group, younger patients were more likely to seroconvert. No severe adverse effects were seen.
Although the study protocol was similar to that advised by the transplantation society, "administration of a single dose of adjuvanted vaccine produced a poor response" in transplant and dialysis patients, compared to the healthy controls, noted the study authors. "In our experience, recently transplanted patients and older patients on hemodialysis are two special populations that probably need at least two doses of vaccine to seroconvert."
"Renal patients do not show the same responses to medical problems as the general population," says Crespo. "Specific studies must be performed to evaluate the efficacy and safety of measure such as vaccination against the influenza A H1N1."
Study co-authors include Silvia Collado, Marisa Mir, Higini Cao, Francesc Barbosa, Consol Serra, Carlota Hidalgo, Anna Faura, Milagros Montero, Juan GarcÃa de Lomas, Juan Horcajada, and Josep M. Puig.