Amid worries about school closures and increased risk of the Omicron variant, some experts say it might be in a family's best interest to opt for a shorter interval between COVID-19 vaccine doses for children between five and 11 years of age, rather than waiting the recommended eight weeks between shots.
Dr. Gerald Evans, chair of Queen's University's infectious diseases division in Kingston, Ont., told CTVNews.ca on Wednesday that choosing to speed up doses "has to be an individual decision by each parent." But for certain children, such as those with medical conditions or who live with high-risk individuals, he said it may make sense to opt for a shorter window between shots.
"A child who's particularly at risk, like an immunocompromised child, I would definitely go with a shorter interval, and I've been recommending that. But if [that's] not the case, it's up to the parents to decide, but I don't think there would be any harm to a shorter interval," Evans said in a telephone interview.
Canada's National Advisory Committee on Immunization (NACI) announced Nov. 19 that it was recommending an eight-week interval between doses for the newly approved Pfizer-BioNTech COVID-19 vaccine for children between five and 11 years of age, rather than the three weeks approved by Health Canada, leaving it up to the provinces and individual clinics to decide which interval is best.
NACI says that while there is no direct evidence regarding an optimal interval for children, it cited evidence in adults that a longer gap may improve immune response and reduce possible side-effects.
Pfizer has said its vaccine doses can be offered three weeks apart for children, and the United States has been following this guidance since the first shots went into kids' arms there on Nov. 3.
Fabien Paquette, vaccines lead for Pfizer Canada, told CTV News in November that through discussions with federal authorities, particularly the U.S. Food and Drug Administration, a three-week interval was agreed upon for Pfizer's clinical programs, as was the case for adolescents and adults.
However, when asked whether it would make any difference to the effectiveness of the vaccine, he said that data isn't available.
Evans explained that vaccine science over history has shown that an interval of about eight to 12 weeks with "most vaccines seems to ensure a more durable response." However, he noted that emerging data is showing that children may actually get more durable responses than adults with shorter intervals of the COVID-19 vaccine.
While he agrees with the reasoning for NACI's eight-week recommendation, Evans said it is ultimately up to parents to decide.
"There wouldn't be anything wrong with going with an interval anywhere between four to eight weeks, which kind of puts you between the clinical trial data and what NACI's saying," Evans said.
Infectious disease expert Dr. Isaac Bogoch told CTVNews.ca that the NACI recommendation of eight weeks is also to help lower the risk of developing myocarditis, a rare condition that can cause inflammation of the heart muscle after vaccination.
"I think we obviously can't ignore that," Bogoch said in a telephone interview Wednesday.
"I think for many people the eight-week duration is going to be reasonable, but there might be individual circumstances where people will choose to shorten," he said, adding that parents should discuss this with their child's health-care provider.
Bogoch stressed that the experts and scientists behind NACI "know their vaccines backwards and forwards," and said their recommendations should not be taken lightly.
He said it is important for Canadians to remember that a first dose is still better than none in the fight against COVID-19 and severe infection.
"We can't ignore the protective benefit of a single dose of the vaccine even if there is a breakthrough infection -- a single dose of a vaccine is still going to be helpful," Bogoch said.
Dr. Anna Banerji, an infectious disease expert and the director of global and Indigenous health at the University of Toronto, said in an email to CTVNews.ca that parents should have their younger children fully vaccinated sooner rather than later amid rising COVID-19 infections.
"I think they need to get the second dose into kids [age] five to 11 ASAP -- as early as three weeks after their first dose," Banerji said Wednesday. "It was studied at three weeks, licensed by Health Canada for three weeks, and now there is a very high risk of exposure."
Dr. Dale Kalina, an infectious disease physician at Joseph Brant Hospital in Burlington, Ont., told CTVNews.ca in an email Tuesday that a shorter interval period is ultimately safe for kids.
"Three to four weeks is still safe as per the trial and Health Canada, and any way to get as many vaccines into children's -- and adults' -- arms as fast as possible, first and second doses, I think is best," Kalina said.
