- 'Keep your guard up': CDC studies show waning COVID vaccine efficacy as delta variant sweeps US https://www.usatoday.com/story/news/health/2021/08/24/covid-vaccine-efficacy-delta-variant-cdc-study-los-angeles/5578703001/?amp%3Butm_campaign=usatodaycomnation-topstories&%3Butm_medium=FeedBlitzRss 23 comments worldnews
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