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

B.C. Finance Minister Selina Robinson outlines the province’s three-year budget in Victoria, April 20, 2021. (B.C. government video)
B.C. deficit to grow by $19 billion for COVID-19 recovery spending

Pandemic-year deficit $5 billion lower than forecast

Raising more than $1,300 for the KVHS’s dementia home project, Dennis and Brenda Horwood leave Kitimat with a bang and start their new retirement journey together. (Photo supplied)
KVHS thanks local Kitimat couple for their contributions to the dementia home project

Dennis and Brenda Horwood raise $1,360 during a retirement garage sale

No increase in fees will be made by the leisure services department in the summer months. Reviews will be made again in May/June for any recommended fee adjustments in the fall. (District of Kitimat photo)
District of Kitimat halt leisure fee increases until the fall

The Leisure Services Advisory Commission recommended no increase take place at this time

Mount Elizabeth Theatre have been approved for a provision of funding by city council for up to $42,000. (Jacob Lubberts photo)
Kitimat’s multi-use theatre grant request approved for live streaming equipment

A funding commitment of up to $42,000 was granted from council to the Mount Elizabeth Theatre

Tracy Owen-Best with her husband, Larry Best. Tracy runs both the Nechako Barbershop and Hair Essentials Salon in Kitimat. Diagnosed with cancer in March 2020, she’s kept a positive mindset with the help from a supportive family. (Photo supplied)
In Our Valley: Tracy Owen-Best

Barbershop owner and cancer fighter keeps it positive

FILE – NDP Leader John Horgan, right, and local candidate Mike Farnworth greet one another with an elbow bump during a campaign stop in Coquitlam, B.C., on Friday, September 25, 2020. THE CANADIAN PRESS/Darryl Dyck
B.C. won’t be using random individual road stops to enforce travel rules: Safety Minister

Minister Mike Farnworth says travel checks only being considered at major highway junctions, ferry ports

A man pauses at a coffin after carrying it during a memorial march to remember victims of overdose deaths in Vancouver. THE CANADIAN PRESS/Darryl Dyck
B.C. announces historic half-billion-dollar funding for overdose crisis, mental health

Of it, $152 million will be used to address the opioid crisis and see the creation of 195 new substance use treatment beds

Children’s backpacks and shoes are seen at a CEFA (Core Education and Fine Arts) Early Learning daycare franchise, in Langley, B.C., on Tuesday May 29, 2018. THE CANADIAN PRESS/Darryl Dyck
B.C. budget to expand $10-a-day child care, but misses the mark on ‘truly universal’ system

$111 million will be used to fund 3,750 new $10-a-day spaces though 75 additional ChildCareBC universal prototype sites over the next three years.

Mak Parhar speaks at an anti-mask rally outside the Vancouver Art Gallery on Sunday, Nov. 1, 2020. Parhar was arrested on Nov. 2 and charged with allegedly violating the Quarantine Act after returning from a Flat Earth conference held in Geenville, South Carolina on Oct. 24. (Flat Earth Focker/YouTube.com screenshot)
Judge tosses lawsuit of B.C. COVID-denier who broke quarantine after Flat Earth conference

Mak Parhar accused gov, police of trespass, malfeasance, extortion, terrorism, kidnapping and fraud

Ambulance paramedic in full protective gear works outside Lion’s Gate Hospital, March 23, 2020. Hospitals are seeing record numbers of COVID-19 patients more than a year into the pandemic. (The Canadian Press)
B.C.’s COVID-19 infection rate declines, 849 cases Tuesday

Up to 456 people now in hospital, 148 in intensive care

Christy Clark, who was premier from 2011 to 2017, is the first of several present and past politicians to appear this month before the Cullen Commission, which is investigating the causes and impact of B.C.’s money-laundering problem over the past decade. (Darryl Dyck/Canadian Press)
Christy Clark says she first learned of money-laundering spike in 2015

The former B.C. premier testified Tuesday she was concerned the problem was ‘apparently at an all-time high’

The city asking the public if they want to pursue legal action against the province and their decision to override the city on the Victory Church issue. (Jesse Day Western News)
Penticton ready to sue province over homeless shelter

City council voted unanimously to authorize legal action

Most Read