The study cites a COVID outbreak which spread rapidly among hospital staff at an Israeli Medical Center — despite a 96% vaccination rate, use of N-95 surgical masks by patients and full personal protective equipment worn by providers.
The calculated rate of infection among all exposed patients and staff was 10.6% (16/151) for staff and 23.7% (23/97) for patients, in a population with a 96.2% vaccination rate (238 vaccinated/248 exposed individuals).
The paper noted several transmissions likely occurred between two individuals both wearing surgical masks, and in one instance using full PPE, including N-95 mask, face shield, gown and gloves.
Of the 42 cases diagnosed in the outbreak, 38 were fully vaccinated with two doses of Pfizer and BioNTech’s Comirnaty vaccine, one had received only one vaccination and three were unvaccinated.
Of the infected, 23 were patients and 19 were staff members. The staff all recovered quickly. However, eight vaccinated patients became severely ill, six became critically ill and five of the critically ill died. The two unvaccinated patients tracked had mild COVID cases.
The authors concluded:
“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.”
According to the paper, the outbreak originated from a fully vaccinated haemodialysis patient in his/her 70s who was admitted with fever and cough and placed in a room with three other patients.
The patient had not been tested for SARS-CoV-2 on admission day, because his/her symptoms were mistaken for a possible bloodstream infection exacerbating congestive heart failure.
To determine the source of the outbreak, researchers conducted phylogenetic analysis on the whole-genome SARS-CoV-2 sequences that were available for 12 cases in the outbreak, including staff and patients from Wards A, B and C and dialysis departments.
All were infected with the Delta variant and epidemiologically and phylogenetically connected to the same outbreak, except for one case. That case and three staff members were not considered part of the outbreak.
“This is a very interesting paper and it is scientifically very sound,” said Dr. Brian Hooker, Ph.D., P.E., Children’s Health Defense chief scientific officer and professor of biology at Simpson University.
“The breakthrough rate of 96.2% of the vaccinated population shows that in this instance, the vaccine was virtually useless in preventing transmission,” Hooker said. “It should also be noted the two reported cases among unvaccinated patients were mild, whereas six of the vaccinated patients died.” Read Full Article >