El Sahly HM. J Infect Dis. 2012;205:703-712.
A higher hemagglutinin dose of the 2009 H1N1 vaccine
improved the vaccines immunogenicity in those with HIV a
population that commonly responds poorly to influenza vaccines.
Patients with low T-cell counts respond the
worst, Hana El Sahly, MD, assistant professor in the department of
molecular virology and microbiology at Baylor College of Medicine, told
Infectious Disease News. Increasing the amount of antigen in
influenza vaccines can partially overcome this hypo-responsiveness.
The randomized clinical trial included 192 participants
aged 18 to 64 years who had HIV. They were stratified by CD4 count and randomly
assigned to receive either two doses of a 15-mcg hemagglutinin (HA) 2009 H1N1
vaccine or a 30-mcg HA 2009 H1N1 vaccine. The doses were given 21 days apart.
HA inhibition and microneutralization antibodies were measured on days 0, 10,
21, 31, 42 and 201.
Hana El Sahly, MD
Those who received the 30-mcg HA dose had significantly
higher HA inhibition geometric mean titers on days 10, 21 and 31, but not on
days 42 and 201. Microneutralization geometric mean titers were also
significantly higher after receiving the 30-mcg HA dose on days 10, 21 and 31.
The researchers then analyzed by CD4 count stratum.
Among those with a CD4 cell count of less than 200 cells/mL, those who received
the 30-mcg HA dose had significantly higher HA inhibition geometric mean titers
on days 21 and 31. The microneutralization geometric mean titers were also
significantly higher in this group on days 10, 21, 31 and 42.
Among patients with a CD4 cell count of at least 200
cells/mL, those who received the 30-mcg HA dose had higher HA inhibition
geometric mean titers and microneutralization geometric mean titers at all time
points, but this was only statistically significant for microneutralization
geometric mean titers on day 10.
Patients with HIV and other immunosuppressive
conditions are at high risk for morbidity and mortality from influenza every
season, El Sahly said. It is important to research their responses
to current vaccines and to look for ways to improve the responses, in the hope
of decreasing the impact of the seasonal epidemic on these individuals.
Disclosure: Dr. El Sahly reported no relevant