In fact, the impact of seasonal vaccine over protection against pandemic influenza induced by pandemic influenza vaccine is presently being studied in different clinical trials by the National Institutes of Health and other agencies (http://clinicaltrials.gov/).gov/
Importantly, in one individual admitted to the intensive care unit with severe respiratory distress syndrome induced by pandemic infection, the same analysis of antibody responses demonstrated poor induction of specific antibody.
However, an influenza virus with high pathogenicity will likely induce an influenza pandemic in the future.
Given that public knowledge of a current pandemic would induce spontaneous social distancing, we believe it reasonable to assume a lower level of community, school and workplace contact and a higher proportion of household transmission (43% rather than approximately 35%).
We suggested that immunization with influenza A H1N1 2009 vaccine can induce immune response to the pandemic virus without major impact on HIV viral replication and immune activation.
Fortunately, trial results suggest that a single dose of pandemic vaccine can induce ostensibly protective levels of antibody, possibly by building on cross-reactive immune memory from prior exposures to seasonal H1N1 virus or vaccine [ 52, 53].
Previous studies using the same methodology to measure T-cell responses have shown that AS03 formulated in A(H5N1) or A/California/7/2009(H1N1 pdm09 pandemic vaccines also induce stronger polyfunctional CD4+ T-cell responses than non-adjuvanted vaccine in adults aged 18 - 60 years [ 14, 31] and in older adults [ 21].
The type of cellular immune response induced by the pandemic H1N1/California vaccine was characterized and compared with that produced by the pandemic H5N1/Vietnam and seasonal H1N1/Brisbane vaccines using inbred Balb/c mice.
These warnings were proven justified 2009 when the world experienced the last influenza A pandemic induced by strain H1N1, also known as swine influenza or new influenza.
Further, loss of protection induced by the pandemic virus was similar for "school" (Φ2 = 38%) and urban populations (Φ2 = 38%), which would be expected following exposure to a virus that was new.
