Albertans are being urged to roll up their sleeves and get their updated vaccine, as doctors warn of another COVID-19 wave.

Bookings for both the latest COVID and flu shots opened on Tuesday and appointments are set to begin on Monday, Oct. 16.

"If you want to reduce your risk of being sick or you want to reduce your risk of being admitted to hospital, the vaccine is effective in all age groups," said Dr. Daniel Gregson, an infectious disease specialist with the University of Calgary's Cumming School of Medicine.

The risk of hospitalization is highest among older Albertans and those under five, making vaccination especially important for them, he said.

"We're having a rise in hospital admissions already. And we now have admitted as many as we did in late spring of this year ... so things are going back up," he said.

While it's difficult to predict COVID trends, Gregson has one key worry.

"I'm concerned that we won't get everybody vaccinated that needs to be vaccinated and that will lead to our hospitals being full," he said.

Last year, a so-called "tripledemic" — including influenza, RSV and COVID — overwhelmed Alberta hospitals.

"What we're seeing is reminiscent of what we're seeing in previous waves," said Dr. Eddy Lang, head of emergency medicine in the Calgary zone.

He's treating COVID patients of all ages in the ER, including people who are young and otherwise healthy.

"The most worrisome thing is the effect of COVID in the elderly and those with high-risk underlying conditions like asthma and chronic lung disease," Lang said, noting many of those patients need IV treatments and oxygen.

As influenza picks up in the coming weeks, he said, the situation will get worse.

"It's very concerning because we know from the Australian experience that the flu season was a very bad one ... and there's no reason to think we won't also be affected."

The latest provincial numbers show 90 confirmed flu cases, 20 hospital admissions, two ICU admissions and one death so far this season.

The province recently changed how it reports COVID-19 statistics. Publicly available data shows, since the end of August, there have been 552 COVID-related hospital admissions, 27 ICU admissions and 40 deaths.

Both doctors are urging Albertans to get their their COVID and flu shots.

"As Albertans we need to do everything we can to improve our health and protect loved ones around us, especially those that are older and have vulnerable conditions," said Lang.

"It definitely will reduce the severity of your infection, reduce your contagiousness and hopefully prevent you or a loved one from ending up in the hospital."

Most Albertans are eligible for the latest COVID -19 vaccine if it has been at least three months since their last shot or infection.

The new COVID-19 formulation, designed to target the XBB.1.5 variant, is expected to be available to Albertans six months of age and older.

The province said it has ordered 1.76 million doses of the updated COVID vaccine and 2.1 million doses of this year's influenza vaccine, which will be arriving in a series of shipments.

Appointments can be booked through the province's online booking system, through community pharmacies or by calling Health Link at 811.