Here's how effective COVID-19 vaccines have been in Alberta

New numbers from Alberta Health are showing just how effective vaccines have been in Alberta in reducing new COVID-19 cases, hospitalizations and deaths. 

The data was released Thursday as part of the province's daily COVID-19 update and is measured since Jan. 1.

The numbers show those most at risk from COVID-19 are either unvaccinated or were diagnosed within two weeks of getting a shot, before the vaccine had time to build up immunity within the body.

"It's clear that vaccines are remarkably effective," Dr. Deena Hinshaw, the province's chief medical officer of health, told reporters Thursday. 

"We can expect both the number of hospitalizations and deaths due to COVID-19 to decrease even more as more of the population is protected by first and second doses."

The province's daily new cases, active cases, hospitalizations and deaths have fallen in recent weeks due a combination of public health restrictions and rising vaccination rates. 

The new data is measured since Jan. 1, and shows that since then: 

  • 0.2 per cent of of people with dose were diagnosed two weeks or more after getting a first dose
  • 0.1 per cent of of people with dose were diagnosed two weeks or more after getting a second dose

Those who were unvaccinated or diagnosed within two weeks of getting a first dose represented:

  • 96 per cent of cases 
  • 93.4 per cent of hospitalized cases
  • 88.4 per cent of deaths

The province lists the partial effective of the Moderna vaccine as 82 per cent with the Pfizer shot listed as 73 per cent. Complete effectiveness for Moderna and Pfizer is listed at 93 per cent and 90 per cent respectively.

Dr. Hinshaw said Thursday the sample size for AstraZeneca shots is too small for proper analysis.

The data also indicates vaccines work well against COVID-19 variants: 

  • B.1.1.7 U.K./Alpha variant: 73 per cent partial effectiveness, 91 per cent complete effectiveness
  • P1 Brazilian/Delta variant: 75 per cent partial effectiveness, 89 per cent complete effectiveness

Vaccine effectiveness measures how well a vaccine prevents infection.

Federal guidelines changed earlier this week to allow mixing and matching of different vaccines.

In Alberta, those who received one of the Pfizer or Moderna mRNA vaccines are recommended to get a second mRNA shot from either manufacturer. 

Those who received a first shot of AstraZeneca have the choice of getting either a second AstraZeneca or a mRNA vaccine.

In a statement, Alberta Health says that to date, "a majority, but not all, of AstraZeneca first doses have opted to receive an mRNA vaccine for a second dose."

Alberta has administered nearly 2.9 million doses of vaccine as of yesterday.

Alberta lifted a number of public health restrictions that had been in place since early May and entered Stage 1 of its reopening program on Tuesday.

With more than 60 per cent of eligible Albertans having had a first dose as well as fewer than 500 COVID-19 patients in hospital, the province has already met the thresholds for Stage 2 of the reopening plan.

Stage 2 relaxes restrictions on outdoor gatherings, sports, and post-secondary institutions among other changes. It is scheduled to begin June 10, two weeks after the vaccination and hospitalization targets were met. 

Stage 3, which lifts almost all restrictions, will begin two weeks after 70 per cent of eligible Albertans have received at least a first dose.