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 woman holds a packet of contraceptive pills. (AP Photo/Tsvangirayi Mukwazhi)
Chilliwack women’s organization among those lobbying for free contraception

Ann Davis Society says while it’s a women’s issue, all of society would benefit from program

Stock photo
Pair’s lawsuit dismissed against Fraser Valley soccer association and churches

Judge in Abbotsford calls claims against 14 defendants ‘an abuse of the court’s process’

RBSS students decorate a parking stall at the school as part of the Paint the Parking Lot project. (Facebook)
2021 Robert Bateman grads ‘Paint the Parking Lot’

RBSS students decorate Abbotsford school’s parking lot for a good cause

The Mennonite Heritage Museum on Clearbrook Road in Abbotsford.
Mennonite Historical Society in Abbotsford seeks input for storytelling project

Digital project asks for stories about living during COVID-19’s ‘changing times’

Provincial health officer Dr. Bonnie Henry updates the COVID-19 situation, B.C. legislature, Oct. 26, 2020. (B.C. government)
B.C.’s COVID-19 case count jumps by 287, another senior home outbreak

Two more deaths recorded, community outbreak in Okanagan

An untitled Emily Carr painting of Finlayson Point was donated to the Art Gallery of Greater Victoria by brothers Ian and Andrew Burchett. The painting had been in their family for several decades. (Courtesy of the Art Gallery of Greater Victoria)
Never before seen painting by famed B.C. artist Emily Carr gifted to Victoria gallery

Painting among several donated to Art Gallery of Greater Victoria

The B.C. Centre for Disease control is telling people to keep an eye out for the poisonous death cap mushroom, which thrives in fall weather conditions. (Paul Kroeger/BCCDC)
Highly poisonous death cap mushroom discovered in Comox

This marks first discovery on Vancouver Island outside Greater Victoria area

100 Mile Conservation officer Joel Kline gingerly holds an injured but very much alive bald eagle after extracting him from a motorist’s minivan. (Photo submitted)
Rescued bald eagle that came to life in B.C. man’s car had lead poisoning

Bird is on medication and recovering in rehab centre

Janet Austin, lieutenant governor of B.C., was presented with the first poppy of the Royal Canadian Legion’s 2020 Poppy Campaign on Wednesday. (Kendra Crighton/News Staff)
PHOTOS: B.C. Lieutenant Governor receives first poppy to kick off 2020 campaign

Janet Austin ‘honour and a privileged’ to receive the poppy

Join Black Press Media and Do Some Good

Pay it Forward program supports local businesses in their community giving

Premier-elect John Horgan and cabinet ministers are sworn in for the first time at Government House in Victoria, July 18, 2017. (Arnold Lim/Black Press)
Pandemic payments have to wait for B.C. vote count, swearing-in

Small businesses advised to apply even if they don’t qualify

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

Court of Appeal for British Columbia in Vancouver. (File photo: Tom Zytaruk)
Sex offender who viewed underage girls as slaves has prohibitions cut from 20 to 10 years

Appeal court reviewed the case of Kyler Bryan David Williams, 29

Most Read