Experts Call for Improved Detection of Respiratory Pathogens

Marilynn Larkin

September 26, 2022

Robust and expanded surveillance systems should be implemented throughout Canada as part of a new approach to detecting novel and re-emerging respiratory pathogens, public health experts say. In addition to current clinical and outbreak management (COM) platforms, a new platform should include wastewater testing, population-based testing, and genomics, they added.

Isha Berry

"While each of these tiers has to some extent been implemented in Canada, the proposed system leverages the existing infrastructure, providing an integrated approach with novel dynamic scaling-up/scaling-down components to support adaptive response and increase system efficiency," author Isha Berry, a PhD candidate in epidemiology at the University of Toronto Dalla Lana School of Public Health, Toronto, Ontario, Canada, told Medscape Medical News. "We suggest that this type of integrated surveillance system could be implemented at several levels, from the federal level to the provincial/territorial level to the regional level."

The authors' analysis was published online Sept. 19 in the Canadian Medical Association Journal.

Three Tiers

The authors propose a "dynamic, integrated surveillance system" that might overcome what they describe as the gaps in COM testing platforms. Such platforms were intended to support clinical care, they note, but have been used in many regions as ad hoc surveillance systems during the COVID-19 pandemic. Relying on these platforms for emerging pathogen detection over the long term could result in undercounting of cases, selection biases, and lagging epidemiological indicators of community transmission, they warn.

The authors' new strategy adds a tiered approach that includes wastewater testing, representative population-based testing, and genomics to existing COM platforms.

The first tier tracks disease signals by testing samples from centralized wastewater facilities to enable the early detection of pathogen resurgence.

The second tier, representative population-based surveillance, uses mailed sample collection kits and online surveys sent to randomly selected households across Canada — including specific populations such as those in long-term care and underhoused and incarcerated individuals — to better understand which groups are affected.

The third tier involves genomic sequencing of a representative subset of samples from the wastewater and population samples to enable analyses of variant severity, immune escape capabilities, and transmission advantages.

The authors acknowledge that the funding and resources necessary to develop and sustain such a system would be substantial. They argue, however, that the system would reduce morbidity, mortality, healthcare costs, and disruptions to society.

Implementation at the federal level would provide insights for national public health emergencies, said Berry. "However, since healthcare policy decisions are, for the most part, under the auspices of provincial/territorial governments, the systems implemented and the information generated at this level are also of value."

Key implementation challenges would include "coordinating efforts across jurisdictions and ministries with different expertise and also having significant sustained financial resources," she added.

The Right Priority?

Commenting on the proposals for Medscape, Stephen A. Hoption Cann, PhD, clinical professor of medicine at the University of British Columbia (UBC) in Vancouver and chair of the UBC Clinical Research Ethics Board, said that the proposed system "could become prohibitively expensive. There would need to be a clear demonstration that the gains would exceed costs." Cann did not participate in drafting the proposals.

Stephen Hoption Cann PhD

The system has potential benefits, however. "Advantages would be a potential for earlier detection for novel pathogens or new variants of existing pathogens," he acknowledged. "But would the lead time be enough to make a difference in the management of the infections that they suggest monitoring — e.g., adenoviruses, enteroviruses, influenzas, noroviruses, and poliovirus?”

While the returns on investment, according to the authors, would be achieved by reducing morbidity and mortality, mitigating economic impact, and decreasing societal disruption through improving public health, "that would only be true if the lead time (likely small) would result in a response that could substantially change the outcome of the latest outbreak — that is, over and above existing systems," Cann said.

"The main obstacles are cost and the competition for healthcare dollars," he explained. Many diseases, such as tuberculosis, are widespread in Canada, particularly among marginalized groups, but these groups are not receiving available treatments, he noted.

Furthermore, he added, "while not as exciting as chasing new COVID variants, monkeypox, or even the latest Ebola outbreak, diseases such as diabetes, hypertension, and metabolic syndrome in our marginalized communities are simply a much more urgent need of focus for our limited healthcare dollars.

“Regular serial testing of wastewater when so many communities across Canada do not even have access to clean drinking water seems like a misdirection of priorities," he said. "These communities would be much better served with resources spent on less glamorous priorities such as housing, food security, employment assistance, and drug and mental health treatment."

The research was supported in part by a Canada Research Chair in Economics of Infectious Diseases held by principal investigator Beate Sander. Berry and Cann reported no relevant competing interests.

CMAJ.  Published Sept. 19, 2022. Full text.

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