Abstract
Currently two vaccines, trivalent inactivated influenza vaccine (TIV) and live attenuated influenza vaccine (LAIV), are licensed in the USA. Despite previous studies on immune responses induced by these two vaccines, a comparative study of the influence of prior influenza vaccination on serum antibody and B-cell responses to new LAIV or TIV vaccination has not been reported. During the 2005/6 influenza season, we quantified the serum antibody and B-cell responses to LAIV or TIV in adults with differing influenza vaccination histories in the prior year: LAIV, TIV, or neither. Blood samples were collected on days 0, 7–9 and 21–35 after immunization and used for serum HAI assay and B-cell assays. Total and influenza-specific circulating IgG and IgA antibody secreting cells (ASC) in PBMC were detected by direct ELISPOT assay. Memory B cells were also tested by ELISPOT after polyclonal stimulation of PBMC in vitro. Serum antibody, effector, and memory B-cell responses were greater in TIV recipients than LAIV recipients. Prior year TIV recipients had significantly higher baseline HAI titers, but lower HAI response after vaccination with either TIV or LAIV, and lower IgA ASC response after vaccination with TIV than prior year LAIV or no vaccination recipients. Lower levels of baseline HAI titer were associated with a greater fold-increase of HAI titer and ASC number after vaccination, which also differed by type of vaccine. Our findings suggest that the type of vaccine received in the prior year affects the serum antibody and the B-cell responses to subsequent vaccination. In particular, prior year TIV vaccination is associated with sustained higher HAI titer one year later but lower antibody response to new LAIV or TIV vaccination, and a lower effector B-cell response to new TIV but not LAIV vaccination.
Highlights
Influenza virus can cause severe respiratory illness in young children and adults, which can lead to death, especially in the elderly over 65 years old [1]
We focused on hemagglutination inhibition (HAI) titer against the H3N2 subtype virus because influenza A/H3N2 has, in recent years, generally been a more virulent strain compared to the other strains and has exhibited more antigenic variation from season to season
Our previous report showed that both trivalent inactivated influenza vaccine (TIV) and live attenuated influenza vaccine (LAIV) induced increased serum antibody titers one month after vaccination [5], a year later, the 904-L group had a significantly lower geometric mean HAI titer compared to the 904-N group (P = .024, unpaired t-test)
Summary
Influenza virus can cause severe respiratory illness in young children and adults, which can lead to death, especially in the elderly over 65 years old [1]. On average 5–20% of the population is infected with influenza virus in the United States every year [2,3], resulting in a considerable economic burden [4]. Most adults and older children have pre-existing levels of antibody because of prior infection or vaccination [5,6]. An individual who was infected by or previously vaccinated against influenza viruses circulating in prior years may still be susceptible to a new virus strain. Influenza vaccines are reformulated each year based on the results of international surveillance that predict the virus strains that will circulate in a subsequent year
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