A comprehensive CDC VISION Network study spanning over 345,000 emergency department encounters and 111,000 hospitalizations found that 2023-2024 COVID-19 vaccines reduced critical illness risk by 48% during the first seven to 299 days after vaccination.
The vaccines demonstrated maximum protection during the first two months after vaccination, with up to 68% reduction in severe cases against critical illness, though effectiveness waned over time particularly beyond six months.
The study reinforces the importance of updated COVID-19 vaccination for vulnerable populations, especially adults 65 and older, as vaccines continued to provide strong defense against hospitalization and death throughout the study period.
Updated vaccines reduced emergency department visits by 24% and hospitalizations by 29%, offering significant protection above and beyond previous infection or vaccination during XBB and JN.1 Omicron subvariant waves.