Optimising Antiviral Strategies for Respiratory Viruses

As a relatively new disease, research into the performance of approved antiviral drugs against SARS-CoV-2 remains limited. George Okoli from the University of Hong Kong investigated the real-world effectiveness of two approved antiviral regimens, nirmatrelvir-ritonavir and molnupiravir, against mild to moderate SARS-CoV-2 infection in over 200,000 individuals in Hong Kong. Using a conditional logistic regression model, his team found that although both drug regimens were effective in treating infection, their effectiveness varied by age. Notably, the nirmatrelvir-ritonavir regimen was associated with significantly decreased odds of disease progression in patients aged 45–64 years, but showed no such benefit in those aged 18–44 years. Okoli suggested that an age-based treatment policy could improve therapeutic outcomes.

Also from the University of Hong Kong, Vania Yun Lin examined how these same drugs affect viral shedding in older, hospitalised patients. Her research explored the influence of treatment timing and pre-existing COVID-19 vaccination status. Lin found that early treatment with nirmatrelvir-ritonavir was associated with a significant reduction in viral shedding duration, regardless of vaccination status. Interestingly, prior vaccination appeared to be more effective than molnupiravir in reducing viral shedding, underscoring the importance of both timing and immune background in antiviral treatment efficacy.

On the innovation front, Bahaaeldin Alhammady from the Leibniz-Institut für Virologie in Germany is developing new antiviral strategies to address rising drug resistance in influenza A strains. Alhammady’s team hypothesised that by using polymerase inhibitors to target the RNA-dependent RNA polymerase (RdRp), they could halt viral replication and overcome existing antiviral resistance. While both favipiravir and baloxavir effectively inhibited RdRp activity and viral replication, baloxavir demonstrated higher potency. However, when the two drugs were tested in combination, they showed antagonistic effects, offering no added benefit over individual treatments.

From age-tailored therapies to novel drug mechanisms, the research presented highlights the diverse and evolving landscape of antiviral and immune therapy development. These insights could inform future healthcare policies and treatment protocols for respiratory diseases, particularly as drug resistance and viral evolution continue to challenge existing therapies.