COVID outbreak among vaccinated people calls into question vaccine-induced herd immunity theory

An article published Sept. 30 in the journal Eurosurveillance questions the validity of “vaccine-induced herd immunity.”

The study cites an outbreak of COVID that quickly spread among hospital staff at an Israeli medical center – despite a 96% vaccination rate, patients’ use of N-95 surgical masks and full use of personal protective equipment by medical workers.

The calculated infection rate among all 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 infected).

The paper notes that several cases of transmission probably occurred between two people, both of whom wore surgical masks, and in one case full PPE was used, including an N-95 mask, face shield, gown, and gloves.

Of the 42 cases diagnosed in the outbreak, 38 were fully vaccinated with two doses of Comirnaty vaccine from Pfizer and BioNTech, one received only one shot, and three were unvaccinated.

Of those infected, 23 were patients and 19 were employees. All of the employees recovered quickly. However, eight vaccinated patients became severely ill, six became severely ill, and five of them died. Two unvaccinated patients had mild cases of COVID.

The authors concluded:

“This report … calls into question the assumption that high rates of universal vaccination will lead to herd immunity and prevent COVID-19 outbreaks… In the outbreak described here, 96.2% of the population was vaccinated. The infection developed rapidly (in many cases, symptoms appeared within 2 days of infection) and the viral load was high.”
According to the article, the outbreak came from a fully vaccinated hemodialysis patient in his 70s who was hospitalized with fever and cough and placed in a room with three other patients.

On the day of admission, the patient was not tested for SARS-CoV-2 because his symptoms were mistaken for a possible bloodstream infection exacerbating congestive heart failure.

To determine the source of the outbreak, researchers performed a phylogenetic analysis of whole-genome SARS-CoV-2 sequences that were available for 12 outbreak cases, including staff and patients from wards A, B and C and the dialysis unit.

All were infected with the Delta variant and were epidemiologically and phylogenetically related to the same outbreak except for one case. That case and three employees were not considered part of the outbreak.

“This is very interesting work, and it’s very scientifically sound,” said Dr. Brian Hooker, Ph.D., P.E., chief scientist at Child Health Advocacy and professor of biology at Simpson University.

“The infection rate of 96.2 percent of the vaccinated population shows that in this case the vaccine was virtually useless in preventing transmission,” Hooker said.

“It should also be noted that the two reported cases among unvaccinated patients were mild, while six of the vaccinated patients died.”

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