according to a study in the International Journal of Infectious Diseases.
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Sanjay S. Patel, PhD, of Novartis Vaccines and Diagnostics, Cambridge, Mass., and colleagues performed a retrospective analysis on an integrated dataset that drew from six randomized clinical trials comparing aIIV3 with nonadjuvanted trivalent inactivated influenza vaccine (IIV3). The dataset comprised 10,794 patients aged 6 months through 5 years, of whom 373 (3%) were deemed at risk of influenza complications after review of their medical history for conditions such as heart disease, asthma, and endocrine disorders.
The rates of solicited adverse events (such as erythema, diarrhea, fever, and localized swelling) were 74% in the aIIV3 group and 73% in the IIV3 group. The rates for any unsolicited adverse events (such as upper respiratory tract infection) for aIIV3 and IIV3 were 54% and 59%, respectively (Int J Infect Dis. 2019. doi: 10.1016/j.ijid.2019.04.023).
One of the six studies included in the dataset randomized 2,655 children for immunogenicity analyses, of whom 103 (4%) were deemed at risk. Hemagglutination inhibition assay geometric mean titers against homologous A/H1N1, A/H3N2, and B strains 21 days after the second of two doses of vaccines were two to three times higher in the aIIV3 than in the IIV3 group, which suggests that aIIV3 is more immunogenic than IIV3. As the investigators noted, this is likely because the adjuvanted vaccine induces a greater magnitude of immune response to the vaccine, something already lower in children than in adults, as well as more breadth of response, meaning the response goes beyond strains included in the vaccines.
The small number of at-risk children in the study poses a limitation on its findings. Dr. Patel and associates said that, regardless, the results of immunogenicity analyses were strong. “Overall, this analysis indicates that aIIV3 has a similar safety profile in young children with underlying medical conditions, consistent with other licensed inactivated influenza vaccines.”
Novartis Vaccines and Diagnostics originally funded the study, but was later acquired by CSL Group and now operates as Seqirus, which continued funding for the study. The authors were employees of one or the other of these companies.