The evolving role of public health data during the COVID-19 pandemic

Public health data and surveillance play a crucial role in managing a pandemic. Throughout the COVID-19 pandemic the volume of data that has been generated is staggering, and while much of this data remains important to track, not every piece holds the same relevance as it once did. As the pandemic and related provincial guidance evolves, so does the data and surveillance needed to control and monitor the spread of SARS-CoV-2 and its impact on the community.

The evolution of COVID-19 data needs in today’s pandemic climate

Public health surveillance involves tracking and forecasting health events and determinants through the collection, analysis and reporting of data and is the backbone of a strong public health system. The data that is collected can tell us how the pandemic is evolving, assess severity, identify groups at higher risk of having poorer outcomes, and help inform public health action aimed at preventing further spread.

Early pandemic surveillance
Since the onset of the COVID-19 pandemic, Public Health Ontario (PHO) has been a leader in data and surveillance reporting, and laboratory testing. In early January 2020, PHO was among the first in Canada to develop a COVID-19 diagnostic test and performed the first test for COVID-19 in the province. We also enhanced testing capacity by reducing the time required to test submitted samples, and increasing the number of tests we could perform each day.

PHO also acts as Ontario’s public health reference laboratory, and leads the Ontario COVID-19 Genomics Network (OCGN). In our role as the reference laboratory, we provide support to new labs as they come online with testing and validate early samples from those labs to confirm the accuracy of the testing. We also evaluate new test methods and provide expertise to inform the evolution of Ontario’s testing strategy, including how these new methods are implemented. The OCGN has the goal of providing timely surveillance of known and emerging variants, and comprised of representatives from clinical and public health laboratories undertaking genomics testing

Our surveillance identified case counts, demographic information such as age group and gender, where and when exposures likely occurred, and how severely the virus was impacting the community. Case counts, transmission and severity data provided an indication of the spread of the virus across Ontario, and populations most vulnerable to infection and severe outcomes.

Surveillance in 2021
With the introduction of COVID vaccines in late 2020, vaccination rates became another key indicator that was monitored as soon as data became available. Due to the limited quantity of vaccinations available during the second wave of the pandemic, there was a stronger focus on high-risk populations, targeting the most vulnerable Ontarians.

Current pandemic surveillance
With the increase of Omicron in Ontario and the recent updates to the provincial testing and case and contact management strategies, case counts are currently an underestimate of the true number of cases and outbreaks across the province, therefore this indicator no longer provides an accurate picture of the spread of the virus.

As provincial guidelines have evolved and testing is available to identified high risk groups, PHO experts are now analyzing several different factors to help tell us where we are in the pandemic. This includes severity data (deaths, hospital and ICU admissions) and the percent positivity rate (the percentage of tests performed that were positive for COVID-19). In the fifth wave of the pandemic these factors tell us about the severity of the virus in the community.

Vaccination rates continue to be a key indicator currently being monitored. Vaccine uptake in Ontario is high with approximately 84.5% of the population aged 5 and older having completed the 2-dose series of a COVID-19 vaccine.

Future pandemic surveillance
It is possible that COVID-19 will shift from its current pandemic phase to one where the virus becomes endemic in Canada. Ongoing public health surveillance of COVID-19 is important to help us better understand spread and movement of the virus, its impact on the broader population and health system, and helps inform public health action to prevent and control its spread.

Public Health Ontario’s role during the pandemic

For the entirety of the pandemic PHO has worked closely with the Ministry of Health (MoH) and our local public health partners to interpret and share COVID-19 data. PHO is a key partner in Ontario’s public health system, and throughout the pandemic we have consistently:

• conducted surveillance of COVID-19 activity in Ontario to support the provincial and regional pandemic response
• provided our partners with scientific and technical information and advice to inform their decision-making and actions
• been a key collaborator in the province’s COVID-19 laboratory testing network
• actively monitored, gathered and analyzed the latest scientific evidence about COVID-19
• supported capacity-building, education, professional development and best practices among Ontario’s health care providers and organizations
• provided operational support to provincial and regional partners

PHO does not create policy, rather our work informs provincial and local policies and guidelines. Our reporting and surveillance efforts evolve with the changing policies to ensure the provincial information systems generate timely, relevant and reliable data, knowledge and tools for our stakeholders. During the pandemic, the analyses that PHO has produced have helped to drive public health action and interventions across the province.