Optimal vaccination strategies for 2009 pandemic H1N1 and seasonal influenza vaccines in humans
Wu J., Zhong X., Li CKF., Zhou JF., Lu M., Huang KY., Dong M., Liu Y., Luo FJ., Du N., Chui C., Liu LQ., Smith NMG., Li B., Shi NM., Song LF., Gao Y., Wang DY., Wang X., Zhu WF., Yan Y., Li Z., Chen JT., McMichael AJ., Yin WD., Xu XN., Shu Y.
A randomized clinical trial was conducted to assess whether the immunogenicity of seasonal and pandemic (H1N1/09) influenza vaccines is affected by the order of vaccine administration. 151 healthy adult volunteers were randomized into three groups. All groups received one dose (15 μg haemagglutinin) each of a pandemic H1N1 vaccine and a seasonal trivalent vaccine. Group 1 received the pandemic H1N1 vaccine first, followed by the seasonal vaccine 21 days later. Group 2 received vaccinations in vice versa and Group 3 received both vaccines simultaneously. Post-vaccination blood samples were collected to determine the immunogenicity by hemagglutination-inhibition (HI), microneutralization (MN), and B cell ELISPOT assays. All three vaccination strategies were well-tolerated and generated specific immune responses. However, we found a significant difference in magnitude of antibody responses to pandemic H1N1 between the three groups. Pre- or co-vaccination with the seasonal flu vaccine led to a significant reduction by 50% in HI titre to pandemic H1N1 virus after pandemic vaccination. Pre- or co-vaccination of pandemic H1N1 vaccine had no effect on seasonal flu vaccination. MN and ELISPOT assays showed a similar effect. Vaccination with pandemic H1N1 vaccine first is recommended to avoid an associated inhibitory effect by the seasonal trivalent flu vaccine. Clinical_Trials identifier: NCT01008137. © 2010.