Thread by @MonicaGandhi9

Wanted to break down this CDC study today to show you how remarkably effective these vaccines are- simply,
-Without vaccination, you would expect among 1000 people to see 162 infections
-With full vaccination among 1000 people, you would see 1 infection
cdc.gov/mmwr/volumes/7…

This MMWR article looked at data from healthcare personnel, first responders, and other essential and frontline workers across six geographic regions in the U.S. from December 14, 2020–March 13, 2021 since vaccines were being rolled out in these groups early.

In total, this analysis involved 3950 participants (in Arizona, Florida, Minnesota, Oregon, Texas and Utah) who have never had COVID-19 before by laboratory tests 2,479 (62.8%) received both recommended mRNA doses and 477 (12.1%) received only one dose of mRNA vaccine by the time

of analysis. In short, there were only 3 PCR-confirmed cases of SARS-CoV-2 after full (two dose) immunization of the 2479 individuals (and 5 between the 1st and 2nd dose). However, there were 161 infections in the 994 people in the cohort who were not yet vaccinated. Even better

than seen in efficacy trials or the U of Texas study. And IMPORTANTLY, 1 more point I wanted to make on the real-world data- those healthcare worker settings at U of Texas/UCLA-UCSD showed the effectiveness of the vaccine during our winter surge – these health care workers

and these first responders in the CDC study were out in the world and cases were surging in throughout the time period covered in our 3rd surge. That is quite a test of the vaccines and they did great (the Pfizer/Moderna trials were conducted during the summer cases not as high)

Limitations of the study include not knowing if any of the 11 infections that occurred after doses of the vaccine were symptomatic, not knowing how often asymptomatic screening was being performed in this cohort, and the fact that we didn’t know the viral load in positive swabs

after vaccination (since recent data shows us viral loads are lower after vaccination and likely not infectious).
medrxiv.org/content/10.110…
medrxiv.org/content/10.110…

@threadreader unroll