The CMAJ article by Petrescu and colleagues1 emphasized the critical interventions — particularly vaccination — that can prevent life-threatening disease in an immunocompromised population. The authors note that vaccination against the polysaccharide encapsulated bacteria Neisseria meningitidis (meningococcus), Hemophilus influenzae, and Streptococcus pneumoniae (pneumococcus) is recommended by the Canadian National Advisory Committee on Immunization (NACI), as published in the 2006 Canadian Immunization Guide.2 Since 2006, recommendations incorporating newer protein conjugate vaccines for N. meningitidis have been made.
Polysaccharide vaccines are poorly immunogenic, even in immunocompetent people. The development of vaccines in which a polysaccharide antigen is conjugated to a protein carrier has resulted in highly immunogenic vaccines against the polysaccharide bacteria S. pneumoniae, H. influenzae and N. meningitidis that are now routinely used in childhood vaccination programs. In May 2007, NACI recommended the use of conjugate meningococcal vaccine for serogroups A, C, Y and W135 for immunization of people aged 2 to 55 with anatomic or functional asplenia, and that this vaccine be considered for asplenic persons 56 years of age or older.3 Menactra (Sanofi Pasteur) and Menveo (Novartis) are 2 quadrivalent meningococcal vaccine products now available in Canada. Unlike the quadrivalent polysaccharide vaccine, regular boosters are not required following conjugate meningococcal vaccine, though some experts recommend a single booster dose 5 years after the initial dose.
In January 2012, Prevnar 13 (PNEU-C-13) (Pfizer), a 13-valent protein conjugate vaccine for pneumococcus, was approved by Health Canada for use in people older than 50 years of age.4 Although no routine Canadian recommendations for offering this vaccine to asplenic adults are available, some experts recommend that clinicians consider using a protein-conjugated pneumococcal vaccine as the initial dose, followed by the polysaccharide vaccine, as this may theoretically improve antibody response and immunologic memory.2,5 In June 2012, the United States Advisory Committee on Immunization Practices voted to recommend Prevnar 13 for use in people aged 19 years or older with functional or anatomic asplenia.6
Physicians should also ensure that adult asplenic persons are offered all routine adult vaccines. An adult schedule may be found at the Public Health Agency of Canada website at www.phac-aspc.gc.ca/im/is-cv/index-eng.php. Vaccine schedules for asplenic children are more complex; one can refer to the Canadian Immunization Guide2 at www.phac-aspc.gc.ca/publicat/ccdr-mtc|/10vol36/acs-12/index-eng.php and NACI updates at www.phac-aspc.gc.ca/publicat/ccdr-rmtc/09vol35/acs-dcc-3/index-eng.php