Two-dose COVID vaccine efficacy durable against severe Omicron but drops in elderly

Overall two-dose vaccine effectiveness (VE) against Omicron variant-related hospitalization or death remained above 70% for at least 6 months among adults in Hong Kong but dropped to below 62% in those aged 80 and older, necessitating a third dose, finds a case-control study published today in JAMA Network Open.

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