Yearly Influenza Vaccination May Protect Children From Future Flu Strains

Repeated seasonal vaccination against influenza in children boosts broadly neutralizing antibodies (bNAb) that may provide immunity against future circulating strains of influenza, according to the results of a recent study. However,  the size of the boost decreases with increasing age.

One way to develop a universal vaccine against influenza is to induce bNAb against the hemagglutinin stalk domain of the virus. Although such antibodies can be boosted in adults by sequential exposure to viruses through natural infection or vaccination, how these antibodies are induced by vaccination in children has been poorly understood.

To evaluate bNAb responses against group 1 influenza A viruses in children, researchers from McMaster University in Hamilton, Canada, assessed the effect of repeated seasonal influenza vaccination and type of vaccine on the induction of these antibodies in serum samples from a cohort of 68 children. All participants were enrolled in cluster, randomized controlled trials of seasonal influenza vaccination with intramuscular injection of inactivated influenza vaccine (IIV). These trials were designed to compare the community protection provided by vaccination with IIV with that produced by vaccination with live attenuated influenza vaccine (LAIV). Participants in the post-hoc study included 37 children who were vaccinated for the 3 influenza seasons from 2008 to 2009 through 2010 to 2011 and 31 controls.

The researchers then assessed the effect of type of vaccine on bNAb induction in children by using serum and mucosal samples from 72 participants in the trials who received either IIV (n = 35) or LAIV (n = 37).

They found that repeated seasonal vaccination increased titers of bNAbs and noted that vaccination with IIV produced a similar increase in titers as vaccination with LAIV. However, in blood, the increase in titers after vaccination was more pronounced with IIV than with LAIV.

In contrast, in mucosa, the increase in titers after vaccination was more pronounced with LAIV than with IIV. For both types of vaccine, the amount of increase in titers after vaccination decreased with increasing participant age.

“These data provide insights into vaccine-elicited bNAb induction in children, which have important implications for the design of universal influenza vaccine modalities in this critical population,” the researchers concluded.

—Ellen Kurek

Reference:

Yegorov S, Celeste DB, Braz Gomes K, et al. Inactivated and live-attenuated seasonal influenza vaccines boost broadly neutralizing antibodies in children. Cell Rep. Published online February 3, 2022. doi:10.1016/j.xcrm.2022.100509