Immunogenicity and reactogenicity to Haemophilus influenzae type B (Hib) conjugate vaccine among rural Alaska adults.
BACKGROUND
Despite routine vaccination and declining disease rates, Haemophilus influenzae type b (Hib) invasive disease still occurs in rural Alaska. Colonization studies indicate persistent transmission of Hib among village residents, including adults. As part of a project to eliminate Hib carriage in three rural villages, we evaluated a cohort of Alaska adults for antibody response and reactogenicity to a single dose of Hib conjugate vaccine (HbOC).


METHODS
75 previously unvaccinated, randomly-selected adults in one village received a single dose of HbOC vaccine and completed a side-effects diary. Sera and oropharyngeal specimens were collected at baseline, two months and one year.


RESULTS
No participants were colonized with Hib or reported serious side-effects. At baseline, 97% of adults had IgG anti-PRP concentrations > or = 0.15 microg/mL, 69% > or = 1 microg/mL, and 28% > or = 5 microg/mL. Two months post-vaccination, 100% of participants had concentrations > or = 0.15 microg/mL, 93% > or = 1 microg/mL, and 86% > or = 5 microg/mL. After 1 year, 98% had IgG anti-PRP concentrations > or = 0.15 microg/mL, 86% > or = 1 microg/mL, and 67% > or = 5 microg/mL. GMCs were 1.9, 33.3 and 8.4 microg/mL at baseline, 2 months and 1 year post-vaccine, respectively (p < 0.01). Serum bactericidal activity increased from a baseline geometric mean titer of 2,205 to 8,349 two months post vaccination and declined to 1102 after one year.


CONCLUSIONS
HbOC vaccine was immunogenic and well-tolerated among Alaskan adults. Nearly 90% of the adults developed an antibody level associated with protection against Hib colonization which persisted for 1 year in 67% of participants.
Dentinger
Catherine M
CM
Arctic Investigations Program, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Anchorage, Alaska, USA. CDentinger@cdc.gov
Hennessy
Thomas W
TW
Bulkow
Lisa R
LR
Reasonover
Alisa L
AL
Romero-Steiner
Sandra
S
Holder
Patricia F
PF
de Leon
Patricia Gomez
PG
Carlone
George M
GM
Parks
Debra J
DJ
Parkinson
Alan J
AJ
Singleton
Rosalyn J
RJ
Levine
Orin S
OS
Butler
Jay C
JC
D000328:Adult; D000413:Alaska; D000907:Antibodies, Bacterial / Q000097:blood; D005260:Female; D018073:Haemophilus Vaccines / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D008875:Middle Aged; D012424:Rural Population; D018074:Vaccines, Conjugate / Q000009:adverse effects* / Q000276:immunology*
D000907:Antibodies, Bacterial; D018073:Haemophilus Vaccines; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D018074:Vaccines, Conjugate