A pediatrician holds a dose of the measles-mumps-rubella (MMR) vaccine at his practice in Northridge, Calif. on Jan. 29, 2015. THE CANADIAN PRESS/AP, Damian Dovarganes

A pediatrician holds a dose of the measles-mumps-rubella (MMR) vaccine at his practice in Northridge, Calif. on Jan. 29, 2015. THE CANADIAN PRESS/AP, Damian Dovarganes

Infants more vulnerable to measles than previously thought: Canadian study

Babies typically don’t receive the measles vaccine until they are 12 months old

A new study suggests infants are more vulnerable to measles infection than previously thought.

The findings debunk notions that most babies are protected for much of their first year by maternal antibodies passed on through pregnancy.

In fact, Toronto researchers from the Hospital for Sick Children and Public Health Ontario say the vast majority of 196 infants they studied were susceptible by three months of age.

And none of the infants were immune at six months.

Babies typically don’t receive the measles vaccine until they are 12 months old. That results in a wide susceptibility gap that the study’s senior author called “quite alarming.”

Shelly Bolotin, a scientist at Public Health Ontario, said the findings underscore the need for everyone to keep their immunization up-to-date to protect the most vulnerable members of the population.

“This is really troubling because measles is a serious disease, and it can be quite serious in infants,” said Bolotin, also an assistant professor at the Dalla Lana School of Public Health and the Department of laboratory medicine and pathobiology at the University of Toronto.

“It can be absolutely devastating and we need to make sure that we are protecting our most vulnerable members of our population — infants.”

The study was published online Thursday and appears in the December edition of the American Academy of Pediatrics journal, Pediatrics.

It found that 20 per cent of one-month-old infants had antibody levels below the protective threshold and 92 per cent of three-month-old babies has levels below the threshold.

Bolotin said researchers already knew infant immunity declines in the first six months of life, but they did not expect such a rapid drop.

“We were surprised to see that waning or that lack of protection start earlier,” said Bolotin, who collaborated with lead author Dr. Michelle Science, infectious disease specialist at Sick Kids and also an infection control physician at Public Health Ontario.

She said the assumption that babies are protected longer is based on studies conducted in places where measles remains prevalent. In those regions, mothers have more robust antibody levels to pass on to their child because their immunity comes through natural infection and is repeatedly boosted by continual exposure to measles.

In contrast, most Canadian women of childbearing age are immune through vaccination because Canada eliminated measles in 1998. Although vaccination rates are high here, immunization through vaccine is associated with lower antibody levels than natural infection.

READ MORE: B.C.’s measles vaccination program gains traction

Bolotin said the Toronto study is unique in measuring antibodies at each month of an infant’s life from birth to 12 months. Previous research has focused on measuring immunity levels among babies at birth or those older than six months.

A companion paper written by two other experts that also appears in Pediatrics raises the question of whether it’s time to consider changing the vaccine schedule. It concludes there’s no reason to vaccinate earlier, despite ongoing outbreaks in the United States.

Bolotin acknowledged this is a challenging question for policy makers who must weigh the risk of infection against the best time to vaccinate children, whose immunity system is still maturing.

Infants between six and 11 months who travel to regions where measles is endemic are encouraged to receive an early dose of the vaccine in addition to their regular 12-month dose, but otherwise, all provinces in Canada recommend the measles, mumps, and rubella vaccine (MMR) at 12 months of age.

The schedule for a second dose of the vaccine varies across the country.

The Pediatrics commentary suggested early vaccination may actually hinder the efficacy of a later dose, resulting in lower levels of the antibody compared with children who first get the vaccine at 12 months.

“Early vaccination may also alter response after re-vaccination, leading to lower levels of the antibody compared with children who are vaccinated for the first time during the second year of life,” they state, citing one study that looked at immunity in children aged five to 10, and another published earlier this year that looked at short- and long-term impacts on children in the Netherlands.

As of late last week, Bolotin said Canada has seen 112 cases of measles this year, the vast majority of them imported or import-related.

Measles can cause severe complications including pneumonia, encephalitis and death.

Cassandra Szklarski, The Canadian Press


Like us on Facebook and follow us on Twitter.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

A dose of COVID-19 vaccine is prepared at a vaccination clinic in Montreal’s Olympic Stadium on Tuesday, Feb. 23, 2021. THE CANADIAN PRESS/Paul Chiasson
39 new cases of COVID-19 in Interior Health region

The total number of cases in the region since the pandemic began is now at 7,334

The Site C Dam location is seen along the Peace River in Fort St. John, B.C., Tuesday, April 18, 2017. The cost of British Columbia’s Site C hydroelectric dam has grown to $16 billion and the completion has been moved up a year to 2025. THE CANADIAN PRESS/Jonathan Hayward
BC Liberal energy critic blasts ‘lack of transparency’ on Site C

MLA Tom Shypitka says Site C going ahead is a ‘good thing’, blames NDP for mismanagement

Kootenay-Columbia MP Rob Morrison speaks during Question Period in the House of Commons. File photo.
Kootenay-Columbia MP supports motion condemning Uighur genocide

Rob Morrison says labelling Uighur persecution as a genocide sends a message to Chinese government

The BC Prosecution Service announced last year that it was appointing lawyer Marilyn Sandford as a special prosecutor to review the case, following media inquiries about disclosure issues linked to a pathologist involved in the matter. (Black Press Media files)
Possible miscarriage of justice in Cranbrook woman’s conviction in toddler drowning: prosecutor

Tammy Bouvette was originally charged with second-degree murder but pleaded guilty in 2013 to the lesser charge

Brent Bidston is the president of Angel Flight East Kootenay. Black Press file photo.
RDEK ponders funding for Angel Flight East Kootenay

The district is considering funding for operations or to eventually help acquire a larger plane

Dr. Bonnie Henry leaves the podium after talking about the next steps in B.C.’s COVID-19 Immunization Plan during a press conference at Legislature in Victoria, B.C., on Friday, January 22, 2021. THE CANADIAN PRESS/Chad Hipolito
COVID: 589 new cases in B.C., and 7 new deaths

No new outbreaks being reported Feb. 26

Staff from the Marine Mammal Rescue Centre, passersby, RCMP and Nanaimo Fire Rescue carried a sick 300-kilogram steller sea lion up the steep bluff at Invermere Beach in north Nanaimo in an attempt to save the animal’s life Thursday. (Photo courtesy Marine Mammal Rescue Centre)
300-kilogram sea lion muscled up from B.C. beach in rescue attempt

Animal dies despite efforts of Nanaimo marine mammal rescue team, emergency personnel and bystanders

Gina Adams as she works on her latest piece titled ‘Undying Love’. (Submitted photo)
‘Toothless’ the kitty inspires B.C. wood carver to break out the chainsaw

Inspired by plight of a toothless cat, Gina Adams offers proceeds from her artwork to help animals

B.C. Finance Minister Selina Robinson presents bill to delay B.C.’s budget as late as April 30, and allow further spending before that, B.C. legislature, Dec. 8, 2020. (Hansard TV)
How big is B.C.’s COVID-19 deficit? We’ll find out April 20

More borrowing expected as pandemic enters second year

The first of 11 Dash 8 Q400 aircraft's have arrived in Abbotsford. Conair Group Inc. will soon transform them into firefighting airtankers. (Submitted)
Abbotsford’s Conair begins airtanker transformation

Aerial firefighting company creating Q400AT airtanker in advance of local forest fire season

Arrow Lakes Caribou Society said the new caribou pen near the Nakusp Hotsprings is close to completion. (Submitted)
Maternity caribou pen near Nakusp inches closer to fruition

While Nakusp recently approved the project’s lease, caribou captures are delayed due to COVID-19

Cannabis bought in British Columbia (Ashley Wadhwani/Black Press Media)
Is it time to start thinking about greener ways to package cannabis?

Packaging suppliers are still figuring eco-friendly and affordable packaging options that fit the mandates of Cannabis Regulations

Join Black Press Media and Do Some Good
Join Black Press Media and Do Some Good

Pay it Forward program supports local businesses in their community giving

The Canada Revenue Agency says there were 32 tax fraud convictions across the country between April 2019 and March 2020. (Pixabay)
Vancouver man sentenced to 29 months, fined $645K for tax evasion, forgery

Michael Sholz reportedly forged documents to support ineligible tax credits linked to homeownership

Most Read