EDMONTON -- Alberta added 1,345 cases of COVID-19 and five deaths on Tuesday.

The province now has 18,481 cases and 476 people in hospital with COVID-19, including 105 in ICU.

Variants of concern, mostly the B.1.1.7 strain first found in the U.K., account for 57 per cent of cases, "meaning transmission is much easier and can happen faster than ever before," Chief Medical Officer of Health Dr. Deena Hinshaw said.

Dr. Hinshaw also said P.1, the strain first identified in Brazil, is growing in the community in many parts of Alberta.

The province's positivity rate decreased slightly on Tuesday to 10.4 per cent.

Alberta has reported 173,531 cases and 2,048 deaths since the pandemic began.

VACCINE UPDATE

Alberta Heath Services has administered 1,196,428 vaccine doses as of the end of Monday. Nearly 240,000 Albertans are fully immunized.

Starting Tuesday, Albertans aged 40-54 are also eligible for the AstraZeneca vaccine previously only given out to the 55-64 age group.

Hinshaw and Health Minister Tyler Shandro received an AstraZeneca dose on Tuesday, and Premier Jason Kenney made an appointment for Thursday.

READ MORE: Younger Albertans line up for AstraZeneca shot rejected by others

The premier told reporters 67,900 appointments have been booked for the next 10 days, and there are only 160,000 doses left with no future shipments yet confirmed.

"If you're over the age of 40, I urge you to take advantage of this opportunity before the supply runs out," Kenney said.

"A word of caution: As much as we'd like to believe that the jab gives us a superpower, please remember that it takes a couple of weeks for the vaccine to work its magic and then we still have to get the second dose when it's available to get the full protective effect. So that first dose is not a licence by any means to ignore or go lax on public health guidelines. We still have to, all of us, keep our guard up and we're counting on Albertans to do that."

The premier announced the province will open AstraZeneca walk-in clinics in every health zone, like the EXPO Centre in Edmonton and Telus Convention Centre in Calgary, this week.

Kenney also revealed the Alberta government expects a Johnson & Johnson shipment in early May.

"We promised to offer every adult a first dose by June 30 as long as supply keeps coming in and we will keep that promise if that supply shows up," Kenney said.

There are 2.3 million Albertans eligible for the COVID-19 vaccines.

SECOND DOSES

Hinshaw explained that once AHS gives first doses to all Albertans, then it will start administering second doses likely at the end of June.

"If you have had a first dose, please do not yet call your pharmacy or AHS to book your second dose," she said. "It will take a few more months to get enough supply for both first doses for everyone and to begin second doses."

She reminded Albertans of the risks of waiting for the Pfizer and Moderna vaccines, and encouraged them to get the AstraZeneca shot right now if they're eligible to protect themselves during the third wave.

"I would like to remind Albertans that waiting for your preferred vaccine is not without risk. It leaves you without the protection of a first dose, possibly for weeks or even months. All vaccines approved for use in Canada are effective at reducing the risk of COVID 19 infection, and even more so the risks of serious outcomes that come with it."