1/ In a new preprint, a group of research organizations analyzed VA records for ~620K people to monitor the change in vaccine efficacy over time. By August, protection against infection had declined to: 3% for J&J; 64% for Moderna; and 50% for Pfizer. 
2/“In summary, although vax remains protective against infection, this protection is waning as the Delta var. has emerged in the U.S. It is not yet clear whether reductions in vax protection against inf. will translate into similar reductions in protection against hosp. & death.”
3/“Patterns of breakthrough SARS-CoV-2 infection among vaccinated Veterans show a worrisome temporal trend, overlapping with the emergence of Delta as the dominant variant in July 2021.”
4/ “Increasing risk of infection was not explained by age or comorbidity, implicating increased infectivity of the Delta variant vs. waning immunity as the primary determinant of infection.”
5/ What was the motivation to use VA data to study vaccine efficacy? —>
6/ “Availability of national data on breakthrough inf. in the U.S. has been severely limited. The CDC trans’d in May from monitoring all reported vax breakthrough cases to focus on identifying ..only hosp. or fatal cases due to any cause, including causes not related to COVID-19”
7/“After it trans. to focus only on breakthrough hosp’s and deaths, the CDC created a database for st. health dept’s to enter info on breakthrough inf’s; however, rep. is not mandatory, and as a consequence, info on risk of breakthrough inf’s is collected haphazardly across U.S.”
8/ This data is adjusted for age and comorbidities.
9/ reference: medrxiv.org/content/10.110…
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