Unvaxxed pose risk of infection for those with shots, research shows as wastewaster suggests COVID soars in Hamilton
Wastewater surveillance for COVID in Hamilton is at its highest since the pandemic began.
The signal shows a steep rise in the last month, soaring well above the peak of the fifth wave as of April 19 - the latest data available.
The surge in the wastewater signal comes as mathematical modelling shows the unvaccinated increase the risk of infection for those who have had their COVID shots.
The choice of some individuals to refuse vaccination is likely to affect the health and safety of vaccinated people in a manner disproportionate to the fraction of unvaccinated people in the population," concluded research published Monday in the Canadian Medical Association Journal (CMAJ).
Although the decision not to receive vaccination is often framed in terms of the rights of individuals to opt out, such arguments neglect the potential harms to the wider community that derive from poor vaccine uptake," stated the study out of the Dalla Lana School of Public Health, the Centre for Immunization Readiness and the Public Health Agency of Canada.
Hamilton's vaccine rollout has been stuck for more than a month with just 58 per cent of Hamilton adults at three doses and some groups particularly lagging - such as those age 18 to 39, which were below 50 per cent.
Uptake has also stalled among kids with 15 per cent of youth age 12 to 17 boosted. Nearly half of children age five to 11 have had no COVID shots, while just over one in three have had two.
In addition, Hamilton hasn't met the goal of getting two COVID shots to 90 per cent of the eligible population for those age 59 and younger.
Anti-vaccine sentiment, fuelled in part by organized disinformation efforts, has resulted in suboptimal uptake of readily available vaccines in many countries, with adverse health and economic consequences," stated the study by University of Toronto researchers Dr. David Fisman, Afia Amoako and Ashleigh Tuite.
Ontario is in the midst of a sixth wave of COVID that has sent rising numbers of Hamiltonians to hospital. St. Joseph's Healthcare and Hamilton Health Sciences (HHS) were caring for 151 COVID patients Monday compared to 119 on April 21 and 78 on April 13.
The city reported the risk of being hospitalized due to COVID is 7.4 times higher among the unvaccinated than for those with three doses. The risk of being admitted to an intensive care unit (ICU) is 14.6 times higher.
Also straining the hospitals were the high number of staff self-isolating, which was at 424 on Monday. The missing workforce comes as HHS reported severe overcrowding, with occupancy at 114 per cent at Juravinski Hospital and 110 per cent at Hamilton General Hospital. Ideal is 85 per cent to 90 per cent.
In addition, HHS had five ongoing outbreaks as of Monday - four at Hamilton General and one at St. Peter's. The outbreaks total 42 cases including 33 patients.
The hospital outbreaks were among 32 in Hamilton high-risk settings including one declared April 21 at Arrell Youth Centre after three tested positive at the detention centre.
There are also 17 outbreaks at seniors' homes, three in shelters and six in group homes and other vulnerable congregate living settings.
While Hamilton's wastewater signal is at its highest, other key metrics haven't yet come close to the records set in the fifth wave's peak in January, including hospitalizations, outbreaks and test positivity.
Average daily new cases were at 170 on April 23 compared to 608 on Jan. 9. These numbers are considered to be a significant underestimate as the general public hasn't had access to PCR testing since Dec. 31.
Wastewater is also tracked by the Ontario COVID-19 Science Advisory Table. While the signal for the province shows a plateau since around April 6, it appears to still be rising in Central West, which includes Hamilton, Brant, Haldimand-Norfolk, Niagara, Waterloo and Wellington-Dufferin-Guelph.
Both HHS and St. Joseph's have been urging the public to get vaccinated to protect the health system during the sixth wave.
The difference COVID shots make was highlighted in the study that found under every scenario the risk of infection was markedly higher among unvaccinated people."
However, they got protection from the vaccinated acting as a buffer to transmission." At the same time, they heightened the risk for those who had their shots when the two groups mix.
Although risk associated with avoiding vaccination during a virulent pandemic accrues chiefly to people who are unvaccinated, their choices affect risk of viral infection among those who are vaccinated," stated the study.
As COVID is airborne, it doesn't even require close-range physical mixing" of the two groups for the virus to spread.
It's significant because vaccine opponents often frame their opposition in terms of the rights of the unvaccinated," stated the researchers about why they did the study.
Many opponents of vaccine mandates have framed vaccine adoption as a matter of individual choice," states the study. However, we found that the choices made by people who forgo vaccination contribute disproportionately to risk among those who do get vaccinated."
Joanna Frketich is a health reporter at The Spectator. jfrketich@thespec.com