Respiratory infections caused by viruses such as influenza and coronavirus are
a serious global problem due to their high infection rates and potential to spark pandemics,
such as the current COVID-19 pandemic. Although preventing these infections
by using vaccines has been the most successful strategy to date, effective vaccines are
not always available. Therefore, developing broad-spectrum anti-viral drugs to treat such
infections is essential, especially in the case of immunocompromised patients or for outbreaks
of novel virus strains. Sialic acids have been highlighted as a key molecule in the
viral infection cycle, with terminally sialylated glycans acting as a target for several viral
proteins involved in infection, particularly respiratory infection. Inhibitors of one such
protein, neuraminidase, are the only anti-influenza drugs currently on the market.
Problems with neuraminidase inhibitors, including the development of resistance and a
relatively narrow spectrum of activity, drive the need for an improved understanding of
the viral infection cycle and the development of more resilient, broader-spectrum anti-viral
treatments. Hence, this review outlines the various roles played by sialic acids in respiratory
viral infection and provides examples of drugs that exploit sialic acids to inhibit viral
infections. It has been concluded that drugs targeting host cell expression of sialic
acid could be especially well suited to inhibiting a broad spectrum of respiratory infections.
This warrants the continued design and improvement of such drugs in an attempt
to lessen the burden of respiratory infections.