Influenza: Can we cope better with the unpredictable?

Area of Science:

• Virology
• Immunology
• Public Health

Background:

• Seasonal influenza vaccines are reformulated annually based on predicted circulating strains.
• Influenza viruses evolve rapidly, leading to potential mismatches between vaccine and circulating strains.
• Such mismatches can reduce vaccine effectiveness and impact public health outcomes.

Purpose of the Study:

• To analyze the predictability of influenza virus circulation.
• To compare circulating influenza strains with recommended vaccine strains over 15 years in the Northern Hemisphere.
• To highlight the impact of vaccine-circulating strain mismatches on vaccine effectiveness.

Main Methods:

• Comparative analysis of historical influenza surveillance data.
• Comparison of circulating influenza strains against World Health Organization (WHO) recommended vaccine strains.
• Review of factors influencing public health impact during mismatch seasons.

Main Results:

• Influenza virus circulation exhibits unpredictability, leading to annual variations in vaccine effectiveness.
• Past seasons, like 2014-15, demonstrated significant mismatches between vaccine and circulating strains.
• Vaccine effectiveness can vary geographically across regions like Europe and North America.

Conclusions:

• Despite unpredictable virus evolution and potential for mismatches, influenza vaccination remains the primary public health recommendation.
• Ongoing research aims to improve influenza vaccine strain selection and composition for enhanced effectiveness.
• Understanding virus dynamics and population immunity is crucial for optimizing influenza vaccine strategies.