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

Vancouver Island University appoints Dr. Judith Sayers as chancellor

Nuu-chah-nulth Tribal Council president is considered a leader in Indigenous rights advocacy

Port Alberni athletes put on fitness ‘FUNdraiser’ for frontline workers

Outdoor boot camp will be limited to 50, with donations helping frontline workers’ mental health

Bamfield residents, visitors pressure province as anniversary of fatal crash approaches

Letter-writing campaign makes ‘heartfelt, emotional pleas’ to improve road conditions

Airforce search and rescue helicopter drops in at Cameron Lake for training

Distinctive yellow CH-149 Cormorant turns heads after using Island lake for impromptu hoist

QUINN’S QUIPS: What makes a building historically significant?

There’s a difference between heritage designation and a heritage register

‘Don’t kill my mom’: Ryan Reynolds calls on young British Columbians to be COVID-smart

‘Deadpool’ celebrity responds to premier’s call for social influence support

Captain Horvat’s OT marker lifts Canucks to 4-3 win over Blues

Vancouver takes 2-0 lead in best-of-7 NHL playoff series with St. Louis

Garbage truck knocks down lamp post onto pickup in north Nanaimo

Emergency crews respond to Dickinson Crossing plaza mall Friday afternoon

Widow of slain Red Deer doctor thanks community for support ahead of vigil

Fellow doctors, members of the public will gather for a physically-distanced vigil in central Alberta

Protesters showcase massive old yellow cedar as Port Renfrew area forest blockade continues

9.5-foot-wide yellow cedar measured by Ancient Forest Alliance campaigners in Fairy Creek watershed

Taking dog feces and a jackhammer to neighbourhood dispute costs B.C. man $16,000

‘Pellegrin’s actions were motivated by malice …a vindictive, pointless, dangerous and unlawful act’

Racist stickers at Keremeos pub leaves group uneasy and angry

The ‘OK’ hand gesture is a known hate-symbol

VIDEO: World responds to B.C. girl after pandemic cancels birthday party

Dozens of cards and numerous packages were delivered to six-year-old Charlie Manning

Most Read