COVID-19 modelling: 98% of B.C.'s recent cases were unvaccinated or newly vaccinated

2nd case of vaccine-induced blood clot in B.C. B.C. has reported another case of a rare blood clot linked to the AstraZeneca COVID-19 vaccine.

Vancouver — Just over 98 per cent of B.C.'s recent COVID-19 cases involved people who were either unvaccinated or had only been vaccinated for less than three weeks, according to health officials.

Data presented Thursday shows that 78,020 of the 79,480 infections recorded in the province between Dec. 27 and May 1 involved people had yet to receive a vaccine or were not fully benefiting from the antibodies generated by vaccination.

The numbers don't tell the full story, as British Columbia only began administering vaccine at the end of December, and the process began very slowly. The province didn't reach the milestone of immunizing 50 per cent of eligible adults until this week.

But other data presented Thursday still suggests a much lower rate of infection in people protected by vaccine. The First Nations Health Authority recorded just 17.6 cases of COVID-19 per 10,000 vaccinated residents, compared to 415.3 cases per 10,000 unvaccinated residents.

Henry noted that the immunity offered by COVID-19 vaccines develops in the body over time, and isn't said to be optimal until 21 days after a shot. And while immunized people tend to experience milder symptoms, they can still suffer serious illness and even death.

"The main risk continues to be age in having severe disease and hospitalization," Henry said.

A total of 1,340 people caught COVID-19 during that December to May timeframe, even though they had been vaccinated at least 21 days prior. Another 120 cases involved people who had received their second dose of COVID-19 vaccine at least seven days prior to infection.

Of the vaccinated individuals who went on to catch the disease, 141 ended up in hospital, including 13 who required intensive care. There were also 30 deaths. Henry noted that seniors tended to suffer the worst outcomes, similarly to what's seen in unvaccinated populations.

"The average age of people who've been immunized who've required hospitalization is 81, the average age of those in ICU is 71, and the average age of those who've died, sadly, is 87," Henry said.

Health officials also shared a promising case study from Prince Rupert, the northern community that was targeted for early immunization back in March due to exploding COVID-19 numbers. The data shows infections began plummeting by late March, and stayed low through April even as cases in nearby communities increased.

"We saw a sustained low level in Prince Rupert itself," Henry said. "This is something that helps us understand what may happen as an entire province once we get to those levels of immunization."

A similar trend was recorded among health-care workers employed in long-term care homes and assisted living facilities, who were among the first in B.C. to receive vaccine. Henry noted there was a "dramatic drop-off" in infections that continued right through the province's brutal third wave of the pandemic.

The province has now administered a total of 2,335,513 doses of the Pfizer-BioNTech, Moderna and AstraZeneca vaccines, including 119,691 second doses.

On Thursday, officials also confirmed B.C.'s second case of rare blood clotting associated with the AstraZeneca vaccine. The latest resident to suffer vaccine-induced thrombotic thrombocytopenia, also known as VITT, is a man in his 40s who lives in the Fraser Health region that spans from Burnaby to Boston Bar.

Henry said the man is in stable condition and receiving treatment.

B.C. is no longer booking appointments for AstraZeneca as a first dose, though existing appointments will proceed as planned and the vaccine will still be given out for second doses.