Abstract
Asplenic individuals are at increased risk for fulminant infections, especially with encapsulated bacteria such as Streptococcus pneumoniae, Haemophilus influenzae type b (Hib) and Neisseria meningitidis, and vaccination is indicated. An inventory was made of the awareness of the infectious risks and vaccination status of asplenic patients in the Netherlands. Less
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than 50% of the patients did receive adequate information about the infectious risks of their asplenic state. For S.pneumoniae, 88% of patients has received a vaccination. For Hib and Neisseria meningitidis, vaccination rates are considerably lower: 32% and 27% respectively are vaccinated. Only 17% of the patients had received all three vaccines (i.e. pneumococcal, meningococcal and Hib), in accordance with international recommendations. Patients were vaccinated with conjugated Hib, pneumococcal and meningococcal vaccines if they were not vaccinated according to international recommendations. In 92 patients, one dose of conjugated Hib vaccine was given. After a single dose of vaccine, 97% of the patients reached the chosen antibody threshold concentration of ? 1.0 g/mL. The responses to both pneumococcal 23-valent polysaccharide and 7-valent conjugated vaccines were analysed in 54 asplenic patients. After one dose of conjugate pneumococcal vaccine, 82% reached the chosen threshold of ? 1.0 g/mL for 5 out of 7 vaccine-serotypes. This percentage rose to 85% and 92% after a second dose of conjugate vaccine and one dose of polysaccharide vaccine, respectively. In 116 patients, the response to the meningococcal serogroup C (MenC) conjugate vaccine was studied. After a single dose of vaccine, 67% of the patients reached the chosen antibody threshold concentration of ? 2.0 g/mL MenC IgG. The quality of the antibodies (expressed as avidity maturation) was poor. After revaccination of patients with a suboptimal response, the response to vaccination rose from 67% to 78%, but again, with only marginal rise in avidity maturation. In 38 patients with breast cancer, the response to influenza virus vaccination was determined at day 4 or at day 16 of a chemotherapy cycle of 21 days. Patients on chemotherapy have significant lower antibody responses than healthy adults. When comparing the two different moments of vaccination during a chemotherapy cycle, vaccination early during the chemotherapy cycle induces better responses than does vaccination in the last week of the cycle. Follow-up studies in larger patient groups are needed to confirm this effect. The response to pneumococcal, Hib, meningococcal and DTP (diphtheria, poliomyelitis and tetanus) vaccines was studied in 26 patients starting at 12 months after allogeneic stem cell transplantation with reduced intensity conditioning regimens (allo-RIST). After two doses of conjugated pneumococcal vaccines, > 73% of the patients developed antibody levels ? 0.35 g/mL for all pneumococcal serotypes included in the vaccine, except for pneumococcal serotype 6B. For Hib and tetanus toxoid (TT), protective antibody levels were found in 77% and 96% of the patients respectively, after one dose of Hib vaccine and two doses of DTP vaccine. Thus, vaccination of allo-RIST patients starting at approximately 12 months post-transplantation induces adequate antibody concentrations in the majority of patients
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