Design the most effective surveillance strategy to detect antigenic changes in circulating influenza strains that could undermine vaccine effectiveness. Which combination of activities would be best?

• A. Randomly sample household pets for influenza-like viruses and use ecological niche modeling to forecast human vaccine failure, since animal sampling always predicts human antigenic variation with perfect accuracy.
• B. Rely solely on passive clinical reporting of severe cases without laboratory sequencing, because clinical severity alone is a sufficient proxy for antigenic change and simplifies logistics while eliminating unnecessary lab costs.
• C. Integrate global sentinel surveillance with frequent viral genetic sequencing, antigenic characterization (e.g., hemagglutination inhibition assays), real-time sharing of data to vaccine strain selection committees, and epidemiologic monitoring of vaccine breakthrough infections.
• D. Delay surveillance efforts until large epidemics emerge and then retrospectively sequence viruses to determine which old vaccine failed, because retrospective analysis is the quickest and least resource-intensive way to inform future vaccine updates.

Answer: (C)