Study coauthored by Dr. Bonnie Henry documents colossal increase in COVID-19 in Metro Vancouver and Fraser Valley
A new research paper shows an astronomical rise in residents of Greater Vancouver and the Fraser Valley being infected by COVID-19 during the last school year.
The largest percentage increase was among those 19 years of age and younger.
The researchers focused on infection-induced seroprevalence (level of a pathogen in a population, as measured in blood serum) over the course of the pandemic. This was done through eight cross-sectional surveys from March 2020 to August 2022.
In all age groups, the infection-induced seroprevalence rate was below 15 percent through September/October 2021.
It rose to around 40 percent by March 2022 after the very infectious Omicron variant had arrived in B.C.
By July/August of this year, it had reached 60 percent. Among those 19 years of age and younger, at least 70 to 80 percent demonstrated infection-induced seroprevalence.
People between 20 to 59 years of age had 60 to 70 percent infection-induced seroprevalence by this summer. The rate fell to 40 percent of adults who were 60 years of age and older.
The preprint of "Serial cross-sectional estimation of vaccine and infection-induced SARS-CoV-2 sero-prevalence in children and adults, British Columbia, Canada: March 2020 to August 2022" has not yet undergone peer review and was posted on the medRxiv website.
The lead author is Dr. Danuta Skowronski, epidemiology lead of influenza and emerging respiratory pathogens at the B.C. Centre for Disease Control. Coauthors include B.C.'s provincial health officer, Dr. Bonnie Henry, and Dr. Mel Krajden, medical director of the B.C. Centre for Disease Control Public Health Laboratory.
The research team mentioned that multiple studies "have reinforced the improved protection afforded by hybrid (vaccine + infection) immunity over that induced by either exposure alone".
A recent SeroTracker meta-analysis noted that protection against Omicron reinfection after prior infection with a pre-Omicron variant "wanes by nearly 50 percentage pts after 15 months with the greatest loss in protection occurring between 3 and 10 months after initial infection".
The same research paper, led by SeroTracker researcher Niklas Bobrovitz, showed a 26 percent reduction in reinfection and 98 percent protection against severe disease over the first nine months for those who've had a full series of vaccinations and prior infection.
The Skowronski-led study noted that publicly funded nucleic-acid amplification testing (NAAT) was widely available in the Lower Mainland and the Fraser Valley until January 2022 for symptomatic people. But access was then restricted to high-risk people as the number of Omicron cases skyrocketed, resulting in a sharp expansion in the use of rapid-antigen tests.
"NAAT (but not RAT) confirmed and epidemiologically-linked cases are reportable to the BCCDC, but reports to date have excluded re-infections," the Skowronski-led team reported.
The team described their approach as "unique in serially-sampling all pediatric and adult age groups and both sexes simultaneously, enabling their direct comparison and extending the information available from other more restricted population subsets (e.g. prenatal sera confined to women of childbearing age, or blood donors confined to mostly non-elderly adults)".
They also acknowledged limitations in the study, noting that residual clinical specimens "are more likely to come from people with underlying comorbidities who may differ in their exposure risk and immune response". These factors could result in an underestimate of infection-induced seropositivity.
"Delay in generating an antibody response and uncertainty in its duration, each also tend toward under-estimation," they added. "Such issue[s] may be suggested in our comparison with anti-S1 detection among mostly unvaccinated children <5 years for whom estimates should be comparable but were ∼10% lower for anti-NP detection."
Province criticized for dropping mask mandate
Last week, Jennifer Heighton, a cofounder of Safe Schools Coalition B.C., accused Henry, Health Minister Adrian Dix, and B.C.'s executive lead on immunization efforts, Dr. Penny Ballem, of "foolishly relying on vaccines as the only layer of protection, despite massive evidence that more is needed".
Safe Schools Coalition B.C. has repeatedly called for universal masking with high-quality masks in schools to control the spread of COVID-19.
In an open letter to Health Minister Adrian Dix and Education Minister Jennifer Whiteside, the coalition and other groups also called for many other policies, including HEPA filtration in every classroom, to catch harmful particles within classroom air.
Since the Skowronski-led study was released, there's been tremendous discussion over Twitter among those who don't feel that the province has done nearly enough to prevent K-12 students from being infected with COVID-19.
You can see some of the comments below, including an 18-tweet thread from Protect Our Province B.C.
Meanwhile, there's a growing body of research into Long COVID. In a recent article in the Atlantic, staff writer Ed Yong addressed one of the common symptoms: brain fog. You can read it by clicking the link below.