Canada approves a second vaccine made without mRNA technology.

Canada’s drug regulator has approved a plant-based coronavirus vaccine that may be a palatable alternative for people who have worried, despite evidence to the contrary, about the safety of the mRNA technology behind vaccines like those made by Pfizer-BioNTech and Moderna.

The regulator, Health Canada, said trials had shown that the two-dose Covifenz vaccine, developed by Quebec City-based Medicago, was 71 percent effective against infection. The approval only covers people ages 18 to 64.

It is the second non-mRNA vaccine cleared for use in Canada. Last week, Health Canada approved a protein-based vaccine developed by Novavax, a company based in Maryland. A scientific advisory panel that makes vaccine recommendations to the government said the Novavax option could be used for people who are “not willing to receive an mRNA Covid-19 vaccine.”

On Thursday, Dr. Howard Njoo, the deputy chief public health officer of Canada, said that to date, the panel had preferred mRNA vaccines because of their effectiveness and “also because of the well-known safety profile.” The panel will offer its guidance on the Medicago vaccine in about two weeks.

Canada has now approved six vaccines, although not all of them are currently available.

Last year, the government agreed to buy 76 million doses of the Medicago vaccine, which is not expected to start arriving in Canada until May. Because 82 percent of Canadians over the age of 5 are already fully vaccinated, according to a New York Times database, officials said this week that many of the doses would probably be sent to other countries.

The Medicago vaccine is based on proteins that resemble the coronavirus to the immune system. Those proteins are produced in a plant that is closely related to tobacco. The vaccine’s effectiveness is increased with an adjuvant made by GlaxoSmithKline.

At the outset of the pandemic, Canada did not have a pharmaceutical company capable of producing a Covid vaccine, which led to initial delays in supply. To help resolve that, the government assisted the development efforts of Medicago, which is owned by Mitsubishi Tanabe Pharma of Japan and Philip Morris International, the tobacco company based in New York. Novavax also agreed to make its vaccine in a government-owned plant under expansion in Montreal.