New seroprevalence study in Québec: One in four people contracted COVID-19 between December 2021 and March 2022

May 9, 2022 – A new seroprevalence study of blood donors, conducted by Héma-Québec, estimates that more than one in four Quebec adults developed antibodies to COVID-19 due to infection between the start of the year and mid-March.

For this fourth phase of the study, analyses were done with tests able to identify antibodies present in people recently infected by SARS-CoV-2. The approach compares the level of antibodies in the same individual, based on two samples taken at different times.

A first sample was collected prior to the arrival of the Omicron variant of concern and another was collected from the same person in 2022, once the Omicron wave was well underway. Using plasma donated to the PLASCOV project, a biobank of plasma samples, this study estimated that 27.8% of the adult Québec population had contracted COVID-19 between the end of 2021 and March 2022.

Direct impact on the activities of Héma-Québec

Daily blood and plasma collection activities have been feeling the effects of the increased presence of COVID-19 in the population. This is especially true since the end of March, corresponding to the start of the sixth pandemic wave. Héma-Québec has been struggling to reach its weekly objectives because of the cancellation of appointments by people who have contracted COVID-19. Yet the need remains the same: every 80 seconds, someone in Québec requires donated blood, and it takes 1,000 donations a day to meet the needs of hospitals.

The current trend being seen cannot continue without eventually having an impact on the blood supply. For this reason, Héma-Québec is launching an appeal to reach the required number of donations. Booking an appointment is the preferred option to ensure Héma-Québec’s teams are prepared to welcome all donors, especially during a pandemic. Héma-Québec invites everyone to plan a donation now by scheduling an appointment online at, or by calling 1 800 343-7264 (SANG).

Individuals who are passing by a blood drive or donor centre are invited to check if they can donate without an appointment. Héma-Québec also asks anyone who has booked an appointment but is unable to make it to remember to cancel the appointment.

Why such studies?

Since the beginning of the pandemic, Héma-Québec has supported public health authorities by conducting seroprevalence studies among blood or plasma donors. "Héma-Québec has privileged access to donors who generously agree to participate in such studies and from whom samples can be easily obtained and analyzed in our laboratories," explains Dr. Marc Germain, Vice-President, Medical Affairs and Innovation. "In addition, our team of researchers has the expertise required to conduct these studies, including antibody research, data analysis and interpretation. With the support of our partners, we have built up a biobank of samples obtained from our frequent plasma donors, which makes it possible to monitor the immune response much more robustly."

These studies are conducted by Héma-Québec, at the request and with the financial support of the Ministère de la Santé et des Services sociaux du Québec. "Seroprevalence studies are proving to be very useful to public health authorities in monitoring the evolution of the pandemic. These data are also essential to validate the models used to predict the evolution of the pandemic," says Dr. Gaston De Serres, Chief Medical Officer of the Immunization Unit at the Institut national de santé publique du Québec.

The project also received funds from the Government of Canada, through its COVID-19 Immunity Task Force (CITF). “The Omicron variant spread quickly, overwhelming SARS-CoV-2 acute infection testing capacities using PCR in Quebec and in the rest of Canada,” says Dr. Tim Evans, CITF Executive Director. “This study thus provides the best assessment of the true scale of infection arising during the first Omicron wave and will help to inform decisions to protect public health moving forward.”

About Héma-Québec

Héma-Québec’s mission is to efficiently meet the Québec population’s needs for blood and other high-quality biological products of human origin. Héma-Québec has over 1,400 employees, nearly 200,000 donors of blood, stem cells, mother’s milk and human tissues, as well as thousands of blood drive volunteers. Every year, Héma-Québec delivers over 800,000 biological products of human origin to Québec’s hospitals in order to meet patients’ needs.

Give blood. Give life.

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Information: Héma-Québec • Media Line | 514-832-0871 •

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