https://www.eurosurveillance.org/content/10.2807/1560-7917.ES.2021.26.39.2100822#html_fulltextWe present an investigation of a coronavirus disease (COVID-19) outbreak that started from one unidentified COVID-19 patient, with extensive, rapid nosocomial spread among vaccinated, including individuals wearing surgical masks.
"In an Israeli hospital outbreak, 96% vaccination rates (and universal masking) made no difference. And guess who had mild cases? Hint: not the vaccinated.
The paper, published in Eurosurveillance, a journal published by the European Centers for Disease Control, explains that the outbreak rapidly spread among both patients and staff of the hospital’s dialysis unit, the Covid-19 ward, and other wards. At the time, 238 out of 248 of exposed patients and staff had been fully vaccinated with Pfizer’s mRNA vaccine.
Again, the fact that 96 percent of the people in this population had been vaccinated - a level far above early estimates of the percentages required for herd immunity - apparently made no difference.
Further, all patients and staff were required to wear surgical masks when they were in the same room, and staff on the Covid-19 unit wore N95 masks and face shields.
Ultimately, 39 out of the 238 exposed vaccinated people (16 percent) were infected, along with 3 out of 10 unvaccinated people - a difference that doesn’t reach statistical significance because the unvaccinated group is too small."
As the authors explained:
“This communication… challenges the assumption that high universal vaccination rates will lead to herd immunity and prevent COVID-19 outbreaks… In the outbreak described here, 96.2% of the exposed population was vaccinated. Infection advanced rapidly (many cases became symptomatic within 2 days of exposure), and viral load was high.”