Lancet publishes research on overall and Delta variant-specific effectiveness of the Pfizer/BioNTech coronavirus vaccine against SARS-CoV-2 and hospitalization for COVID-19 over time, in the context of potentially waning immunity. The researchers followed outcomes among 3,46,957 people in a large US-based healthcare system between 14 December 2020 and 8 August 2021. Among people who were fully vaccinated, at four months post-vaccination overall effectiveness against infection and hospitalization were 73 percent and 90 percent, respectively. But the vaccine’s effectiveness against SARS-CoV-2 infection dropped from 88 percent during the first month after vaccination to 47 percent after five months post-vaccination. The trend of declining effectiveness was seen against non-Delta variants (from 97 percent to 67 percent at four to five months post-vaccination) as well as Delta (from 93 percent to 50 percent after four months post-vaccination. Nonetheless, effectiveness against hospitalization with the Delta variant remained strong, at 93 percent for up to six months. Source

• The New York Times reports that J & J is planning to seek US FDA authorization for a booster dose of its coronavirus vaccine. FDA already scheduled an advisory committee meeting about granting emergency use authorization for a J & J booster, after a CDC study reported that the single-dose J & J vaccine was less effective against hospitalization from COVID-19 than mRNA vaccines (71 percent, versus 88 percent for the Pfizer/BioNTech vaccine and 93 percent for the Moderna vaccine). The CDC researchers noted that “Real-world data suggest that the two-dose Moderna and Pfizer-BioNTech mRNA vaccine regimens provide more protection.” Source

JAMA publishes a study on incidence of myocarditis and clinical outcomes among 2,392 ,924 adults given mRNA vaccines and a control group of 1,577, 741 unvaccinated adults, using on data collected from a large US healthcare system between 14 December 2020, and 20 July, 2021. Overall, there were 90 cases of myocarditis – 15 among males ages 20-32 in the vaccinated group (two after the first dose and 13 after the second dose). The observed incidence was 0.8 cases per million first doses and 5.8 cases per million second doses over a 10-day observation window. All were hospitalized, and their symptoms (most commonly chest pain) resolved without ICU admission. Source

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