COVID-19 vaccines in any combination have maintained their effectiveness four months after second doses, according to the latest data from the B.C. Centre for Disease Control.
Provincial health officer Dr. Bonnie Henry says protection against infection and hospitalization has been shown to be greater with a gap of more than six weeks between doses, a decision made earlier in the pandemic when vaccines were in short supply.
The results show more than 90 per cent of people with two doses have been protected from from serious illness with Pfizer and Moderna mRNA vaccines, while protection from infection declined towards 80 per cent as the time interval approached 16 weeks. Protection from infection was “slightly decreased” for people who have two doses of AstraZeneca vaccine.
“What this tells us quite clearly is that for the majority of people, two doses of any vaccine, no matter what combination received, has been shown to be highly effective and continues to be protective against both the infection and hospitalization across B.C.,” Henry said at a pandemic briefing Sept. 28. “This is good news, and it also includes the period of time where the Delta variant has been the majority of cases that have caused illness here in B.C.”
Booster third doses are now being offered to people with severely compromised immune systems, and will be delivered to seniors in care facilities in October. Those seniors were the top priority when vaccination began in B.C. late in 2020.
“The data that’s come out shows that somewhere around six months after dose two is probably the best time to do that,” Henry said. “Starting next week, we will be providing a booster dose for residents of long-term care and assisted living. We know that our senior and elders have carried a heavy burden. We continue to see cases in these homes.”