4. Discussion
The COVID-19 pandemic caused by SARS-CoV-2 and its variants continues to
pose a threat to human health globally. Although vaccination brought the
pandemic under control to some extent, the large number of breakthrough
infection cases may require annual COVID-19 vaccination. IAV is a common
respiratory infectious virus that causes severe respiratory illnesses
worldwide. WHO updates vaccines to prevent seasonal influenza epidemics
every year. It was reported that the coinfection rate of SARS-CoV-2 and
IAV during the COVID-19 pandemic was as high
asĀ 49.8%.21 To date, no clinically effective
prophylactics are available for the prevention of both SARS-CoV-2 and
IAV infections, highlighting a need for the development of combined
vaccines. The production of a combined influenza/SARS-CoV-2 Omicron
vaccine capable of protecting from both IAV- and SARS-CoV-2-induced
disease may reduce the cost, inconvenience, and administration burden of
multiple independent vaccines. In our study, the immunogenicity and
protective effect of the influenza/SARS-CoV-2 Omicron subunit combined
vaccine adjuvanted with MF59 were evaluated in BALB/c mice. Data showed
that the combined vaccine induced high levels of IgG,
IgG1, and IgG2a antibodies, as well as
influenza A H1N1/California/2009 virus-specific
hemagglutination-inhibiting antibodies in BALB/c mice. Furthermore, the
subunit combined vaccine induced high titers of neutralizing antibodies
against SARS-CoV-2 Omicron BA.5 pseudovirus infection and effectively
reduced the viral load of authentic SARS-CoV-2 Omicron BA.5.2 variant in
the cell culture supernatants.
In conclusion, our study educed evidence showing the
influenza/SARS-CoV-2 Omicron subunit combined vaccine to be a potential
interventional candidate against COVID-19 and pandemic influenza
coinfection, thus deserving of further translational development.
Author Contributions: N.Z., H.H., S.J., and J.Z. conceived the
idea and designed the experiments. Z.Y., C.L., J.Z., W.X., L.X., Y.C.,
R.Y. and J.D. performed the experiments. N.Z. and Z.Y. analyzed the
data. N.Z. wrote the draft, and J.Z., S.J. and H.H. revised the
manuscript. All authors have read and agreed to the published version of
the manuscript.
Funding: This work was supported by the Scientific Research
Foundation (grant No. J-202106) and Innovation Training Program (grant
No. X202301126) of Hangzhou City University to N.Z.
Conflicts of Interest: The authors declare no conflict of
interest.