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Scientists use dried blood spot testing to study spread of COVID-19 in Canada

Dried blood spot (DBS) testing, a technology used by scientists at the Public Health Agency of Canada’s National Microbiology Laboratory (NML), is innovating how we screen for transmissible diseases in Canada. It has a variety of uses, from testing for sexually transmitted and blood-borne infections (STBBIs) to testing for antibodies from previous infections such as COVID-19. The NML is using DBS testing to serve a variety of community settings, including lending its expertise to a country-wide survey to test for COVID-19 antibodies.

A minimally invasive method

Dr. John Kim, Chief of the NML’s National Laboratory for HIV Reference Services, and his team are using DBS technology for serology testing to determine past infections to diseases such as the virus that causes COVID-19. The team is participating in multiple studies that are measuring antibodies in populations such as people in long-term care homes, teachers, correctional services, LGBTQ2+ populations and pregnant women.

DBS testing is a minimally invasive method of collecting a blood sample. The individual pricks their finger and places it on a special filter paper. The blood dries on the paper and the sample is mailed to a laboratory for analysis. It does not require a trained medical professional to collect the sample unlike the traditional method of drawing blood with a needle. It is a particularly valuable technology in remote locations, where people may not have access to clinics that provide conventional methods of blood testing. The samples are easier to transport with a lower risk of spoiling and are more accessible for people who are hesitant to get their blood drawn with a needle or want to remain anonymous in testing.

Self-collection kits make Canada-wide survey possible

The NML recently played a significant role in Statistics Canada’s COVID-19 Antibody and Health Survey, in partnership with Canada’s COVID-19 Immunity Task Force (CITF). The study sent out at-home DBS testing kits to collect blood samples, which were analyzed to see how many Canadians have COVID-19 antibodies. This was the largest survey in Canada to date using a self-collection method with over 10,000 participants. The data was collected from November 2020 to April 2021.

“There were two questions we wanted to ask—who had COVID-19 and how effective are the vaccines?” says Dr. Kim.

This research helped scientists better understand the spread and impact of the virus among Canadians, their immune response to vaccination, and the socio-demographics of those who were infected. The findings also shed light on how many Canadians were infected but asymptomatic—meaning they did not get sick or had very mild symptoms and did not seek diagnostic testing. (Learn more about the study’s results here.)

The NML played a critical role and provided supplies, training and data analysis for the project. Dr. Kim and a team of researchers across Canada established the testing method used to process the DBS samples to determine the immune status of Canadian populations. They used DBS specimens to compare the tests for accuracy and reliability. They also helped with storing the samples and transporting them to specialized laboratories for analysis. In addition, the NML used the data in mathematical models to assess different projections that helped inform the actions that needed to be taken to minimize the impact of the virus in some communities.

A second cycle of the survey is set to take place in April 2022.

Success bodes well for future studies

Testing for antibodies with DBS kits has proven to be a highly effective way to test blood samples from thousands of Canadians across the country because they are easy to distribute, administer and return. Without DBS testing, it would not have been possible to test Canadians in such a representative manner. As the use of DBS technology increases, it is making it possible to do studies in populations such as children, Indigenous peoples, correctional settings and many others, thus helping researchers obtain samples that are more representative of the population given the increased participation rates.

Dr. Kim believes the success of this study will pave the way for the NML’s future activities regarding testing for other infectious diseases. For the past several years, the NML has provided DBS tests to at-risk populations and First Nation, Métis and remote communities to test for STBBIs such as HIV, Hepatitis C and syphilis. The goal of this work was to help people increase their awareness of their health status and ultimately reducing rates of disease by increasing accessibility and reducing the stigma surrounding testing.

The NML plans to continue its rollout of DBS testing and localized training in First Nations, Métis and remote communities. This work directly addresses several of the key pillars outlined in the Government of Canada’s five-year action plan on STBBIs; in the spirit of truth and reconciliation and community innovation. Innovative options for testing, like DBS, help reach the undiagnosed by reducing the stigma and discrimination associated with conventional methods.

“The COVID-19 study with the CITF and Statistics Canada showed that people are able to take their own blood samples. This bodes well for when we start to encourage increased use of DBS testing. More Canadians will be aware and accepting of it as a method to learn more about their health status,” says Dr. Kim. “With this knowledge, people in Canada can take action to improve their health and seek care if needed.”


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