Dr Dominik Mertz, HHS Medical Director of Infection Prevention and Control, presented the analysis at a town hall on Thursday. The five outbreaks included units E3, B3, F5, E4 and M2, which run from one clinical teaching unit to another providing an alternative level of care for people awaiting long-term placement.
City spokesman James Berry said the outbreaks spread between December 3 and January 12, with 106 infections and nine deaths.
The presentation at HHS Town Hall shows some of what happened between December 3, 2020 and December 22, 2020.
Mertz said there were four strains of COVID-19 among the 33 cases sampled by the hospital network, but only one of those strains, B.1.369, has spread in the outbreaks.
Neither strain was the variant of concern that currently accounts for about half of new daily infections in Hamilton.
Mertz said the B3 unit outbreak had three cases between December 3-4.
He also said he was most likely linked to the E3 unit by a health worker, although in an interview on Tuesday Mertz said there was no way to know for sure.
He said during the E3 outbreak, after the virus entered the unit, patients were infected and then it spread to other staff between December 3 and December 22.
“You can see how it went through our parish,” he said.
The third epidemic was declared on December 4 in the E4 district.
It was also the first of the outbreaks to see a new strain of the virus, although Mertz said that strain was not really linked to the other cases.
The epidemic saw seven cases between December 10 and December 17.
Then two more outbreaks occurred.
The F5 epidemic was also declared on December 4, but the first case was a new strain that did not spread.
Then on December 6, two people were infected with the main strain and a third person had another variant (although it also did not spread).
A week later, four more received the main strain. And it infected three more over the next seven days.
The M2 service had three cases, one of which was a strain that did not spread.
The other two cases were linked, with one person contracting the virus on December 19 and the other on December 20.
Mertz said on Tuesday that these outbreaks were most likely related by patients.
“The typical transfers that we have from a medicine or surgery unit to F5, which at the time was our alternative level of care… that’s why we transferred people to those units before we knew we had a epidemic, ”he said.
“Because they were incubating at the time and developed the infection in the unit, we saw limited spread. “
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Mertz said it reinforces what experts have said about the outbreaks.
“We saw a spread and we had a particular strain that was responsible for the vast majority of these cases,” he said.
Mertz added that the cases were not caused by long-range air spread, with most cases occurring in rooms with multiple beds.
“It’s this model of a here, one there, one there… which wouldn’t be what you would expect with a classic airborne pathogen like measles,” he said on Tuesday.
At city hall, he added that there was not a single person, piece of equipment or shared service leading to dozens of infections.
He also said it was not a failure of personal protective equipment.
Mertz said the best way to avoid the spread would be to avoid moving beds or staff between units.