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Ilana Diener holds her son, Hudson, 3, during an appointment for a Moderna COVID-19 vaccine trial in Commack, N.Y. on Nov. 30, 2021.EMMA H. TOBIN/The Associated Press

Moderna, Inc. has officially asked Health Canada to authorize its COVID-19 vaccine for children as young as six months old, making the company the first to seek Canadian approval to inoculate babies, toddlers and preschoolers against the pandemic virus.

Patricia Gauthier, Moderna Canada’s general manager, said at a news conference that the company submitted its application to Health Canada on Thursday night, not long after it filed for approval in the United States.

“We’re really proud to announce that we filed to Health Canada [Thursday] night our dossier to ask for the extension of the indication for a vaccine so that we could protect potentially infants as early as six months of age,” Ms. Gauthier told a Montreal audience at an event announcing plans for a Moderna vaccine plant in Quebec. “So it’s now in the hands of Health Canada.”

Moderna to open vaccine manufacturing plant in Montreal area

Many Canadian parents have been waiting eagerly to find out when the shot will be available to the youngest children. Right now, Health Canada has approved the Pfizer-BioNTech shot, sold under the brand name Comirnaty, for children as young as 5, and Moderna’s SpikeVax shot for children as young as 6.

It’s too early to say how soon Health Canada will rule on Moderna’s application. Evaluating the submission may not be as straightforward as previous applications for COVID-19 vaccines, partly because of the way the Omicron variant affected the clinical trials.

In a summary released in March, Moderna reported that its trial involving 6,700 children between the ages of six months and six years met its primary goal, which was to show that a quarter-dose of the vaccine was safe and produced an immune response in line with that of young adults who received a full dose.

At the same time, the trial, which took place during the Omicron-fuelled winter wave, followed participants to see if they caught the coronavirus. An analysis of those data found the vaccine’s efficacy rate against COVID-19 infection was 43.7 per cent for children six months to two years and 37.5 per cent among children 2 to 6.

That’s a far cry from the efficacy rate of 95 per cent that Moderna reported before its vaccine was approved for adults in late 2020. But the virus has evolved significantly since then; the Omicron variant is different enough from the original virus that it can escape much of the vaccine’s protection against mild infections.

However, the vaccines from Moderna and Pfizer-BioNTech have continued to provide robust protection for adults against severe disease and death in the age of Omicron, especially for those who’ve received a third dose.

Moderna’s trial in the youngest children didn’t reach conclusions on severe disease because none of the participants got seriously sick, required hospitalization or died, regardless of whether they received a real shot or a placebo – a reminder of how rare it is for young children to suffer severe outcomes from COVID-19.

None of the participants developed heart inflammation, a rare side effect of the mRNA vaccines detected in teens and young adults. Other side effects were mild and similar to those seen with other pediatric vaccines.

“How we argue that we should or should not vaccinate small kids will require some subtlety and will require some nuance,” said Srinivas Murthy, a pediatric infectious diseases specialist and professor in the department of medicine at the University of British Columbia. “Most kids have had Omicron over the past three to six months. The added value and the added risk of this vaccine is something that needs to be thought about very carefully, and hopefully Health Canada and the [National Advisory Committee on Immunization] think about it very carefully as well.”

Pfizer-BioNTech has not yet submitted an application to Health Canada for approval of its vaccine in babies, toddlers and preschoolers. The companies are gathering data on adding a third dose to their regimen after early trial results suggested the tiny dose of mRNA the companies tried wasn’t strong enough to elicit protection for children between the ages of 2 and 5.

Canada’s overall COVID-19 vaccination rate is among the highest in the world, but uptake hasn’t been as high for children between the ages of 5 and 11. Only 41 per cent in that age category have received two doses, compared with 89.5 per cent for people 12 or older, according to data from the Public Health Agency of Canada.

News of Moderna’s application emerged on the same day the Massachusetts-based company fleshed out its plans for a manufacturing plant in the Montreal area that will eventually pump out shots for COVID-19 and other respiratory illnesses, along with future vaccines for whatever yet-to-emerge virus sparks the next pandemic.

Moderna chief executive officer Stéphane Bancel, Prime Minister Justin Trudeau, Quebec Premier François Legault and other politicians gathered at McGill University to announce the 10-year agreement, which includes a Moderna commitment to spend an unspecified amount of money on scientific research in Canada.

Moderna and the federal government said last August that they had signed a memorandum of understanding that would culminate in Moderna making Canada the site of its first manufacturing plant outside the United States, but the parties did not announce a location until Friday.

Messenger RNA is a single-stranded molecule that transmits instructions for cells to manufacture proteins. In the case of the mRNA vaccines for COVID-19, the shots were encoded with a message telling cells to make the spike protein that studs SARS-CoV-2, coaxing the immune system to mount a defensive response it could repeat if the real virus ever showed up.

“For the first time in the history of medicine, we have a molecule that is an information molecule, and that changes everything,” Mr. Bancel said. “It is like going from Blockbuster to Netflix. It is a change of paradigm and we’re bringing this technology to Canada, which we’re very excited about.”

Prime Minister Justin Trudeau and other government officials have announced that Moderna will set up a vaccine factory in Montreal. The facility will be able to produce 100 million doses of mRNA vaccines a year and will help develop top scientific talent in Canada.

The Canadian Press

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