Feb 17 (Reuters) - Canada on Thursday approved Novavax Inc's COVID-19 vaccine for people aged 18 years and older, making it the fifth such shot to be cleared for use in the country.

The vaccine's safety and effectiveness in people younger than 18 years have not yet been established, Health Canada said in a statement.

Novavax's recombinant protein vaccine, Nuvaxovid, uses a more established technology than mRNA, the novel method behind the two most commonly used COVID-19 vaccines - from Pfizer-BioNTech and Moderna.

Some experts have voiced hopes that Novavax's product could convince as-yet unvaccinated people who are skeptical about the novel mRNA technology to get a shot.

"Having more authorized COVID-19 vaccines provides provinces and territories with an additional option ... it can help remove barriers to vaccination by providing an additional option to adults who have not yet received a COVID-19 vaccine," Canada's chief public health officer Theresa Tam told reporters at a briefing.

About 80% of Canadians have received two doses of a COVID vaccine https://tmsnrt.rs/3tUM8ta, and over 40% have also received a third or a booster shot.

On Wednesday, Novavax Chief Commercial Officer John Trizzino said there is still significant demand for vaccination across the globe, especially in light of Omicron, the threat of more variants and a high percentage of unvaccinated people who need primary vaccination.

"We also know that many of the booster programs that are in process right now will drive demand for our product."

While Nuvaxovid is not currently authorized for use as a booster dose in Canada, it may be offered as a booster to people who are unable or unwilling to receive an mRNA vaccine, Tam said.

The Canadian government has committed to purchase 52 million doses of the vaccine, with an option to buy up to 24 million more doses. The first shipment of the vaccine is expected to arrive in the country in March, health officials said.

Novavax has been plagued by supply and manufacturing issues as well as regulatory delays, and has delivered just a small fraction of the 2 billion COVID-19 shots it plans to supply worldwide in 2022.

The company expects to supply 27 million doses of its vaccine to Europe in the first quarter, but did not provide guidance on how many overall doses it plans to ship during the period.

Novavax's protein-based vaccine is being reviewed by the U.S. Food and Drug Administration and has received approvals from the European Union and the World Health Organization.

(Reporting by Mrinalika Roy and Ismail Shakil in Bengaluru; Editing by Devika Syamnath and Lisa Shumaker)