Lead author Dr. Danuta Skowronski, an epidemiologist at the BC Center for Disease Control, said the findings are generalizable to the rest of Canada, in part because of the push to deliver the first vaccine doses and the Omicron “beast,” which has driven wave after wave of infections. Antibodies against SARS-CoV-2, the virus that causes COVID-19, can be detected in the blood of people who have recovered from the disease and among those who have been vaccinated. The researchers looked for antibodies in the remaining blood of 14,000 people who had laboratory tests in British Columbia between March 2020, before the World Health Organization declared a pandemic, and August 2022, as the rapidly spreading Omicron variant evaded vaccine protection. They performed eight analyses, corresponding to snapshots of the presence of the virus in the population during the study period. The study, published Monday in the Canadian Medical Association Journal, found that by January 2021, less than 5% of people had been exposed to the virus. But the percentage of those with antibodies to COVID-19 rose to 56 percent in June 2021 as vaccines became available. It jumped to 95% in August this year through a combination of vaccination and infection as Omicron became the dominant variant. “The highest rates of infection were in children and adults of parental age. This likely reflects their greater interconnectedness, socially,” Skowronski said, adding that while data from other provinces is limited, similar findings have been reported in the United States. The lowest rates of infection were in the very old, as can be seen elsewhere in the world. He said this is likely due to social isolation and the high rate of vaccinations and boosters in this age group, which is also at the highest risk of serious illness. This points to the need to prioritize the elderly for vaccination, Skowronski said. The BC Center for Disease Control started similar seroprevalence surveys, which measure rates of a particular disease in a population over time, during the 2009 swine flu pandemic caused by the H1N1 influenza virus. He completed several surveys during the COVID-19 pandemic, including one published in September suggesting that at least 70 to 80 percent of children and youth in Greater Vancouver and BC’s Fraser Valley were infected. Another seroprevalence study is set to begin later this month to continue monitoring traces of the virus, Skowronski said. The data can inform policy decisions in real time because without antibodies, a large percentage of the population is susceptible to infection in a pandemic, and that would overwhelm the health care system’s capacity, he said. “As (the research) unfolded, there were a lot of things that I thought were really quite remarkable and kind of spoke to the decisions that had been made in B.C., but not just in Canada, because I think our findings can be generalized to other areas”. The rapid release of vaccines helped prevent further spread, he said. “Canada went from being in a precarious position in January 2021 in terms of vaccine supply to becoming in June 2021 the world leader in vaccine coverage – surpassing the United Kingdom and even Israel in terms of the proportion that had been vaccinated. And we show that in our HIV prevalence survey, that rapid uptake in vaccine coverage.” Caroline Quach-Thanh, professor of microbiology, infectious diseases and pediatrics at the University of Montreal, will co-supervise a study that will investigate antibodies in children up to 17 years of age to detect the presence of prior COVID-19 infection and/or vaccination. The research team wants to take 36,000 samples of residual blood from emergency departments at 14 children’s hospitals over five trial periods starting in January 2023. The annual study will include all provinces except Manitoba. New Brunswick and Newfoundland and Labrador will be excluded because they do not have children’s hospitals. The hope is to get more data on how COVID-19 has affected youth in different provinces and be at the forefront of what the pandemic may bring next, Quach-Thanh said. “The question is: Can we get something new that might come?” — Camille Bains, The Canadian Press RELATED: BC COVID response praised for ‘agility’, despite lack of public confidence: review RELATED: The federal government still strongly encourages people to use masks while traveling Health vaccines for the coronavirus
