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

Cloverdale robbery suspect. (Surrey RCMP photo)
Man charged in relation to four separate robberies in Cloverdale

Jake Eric Henderson allegedly committed four gas station robberies in January

Surrey Pretrial in Newton. (Photo: Tom Zytaruk)
Tribunal to hear transgender inmate’s human rights complaint against Surrey Pretrial

B.C. Human Rights Tribunal member Amber Prince on March 3 dismissed the pretrial’s application to have Makayla Sandve’s complaint dismissed

An eagle sits in trees overlooking 1001 Steps in South Surrey, January 2021. The City of Surrey has received international recognition as a ‘tree city’ but an environmental group calls it an ‘empty accolade.’ (Tracy Holmes photo)
Environment organization calls Surrey’s ‘tree city’ designation ‘empty accolade’

Committee chair Allison Patton says international recognition is encouraging and sets a trend

Live Well Exercise Clinic CEO Sara Hodson and Trevor Linden’s Club 16 partner Carl Ulmer are pushing for gym memberships and services to become tax deductible. (Contributed photo)
Semiahmoo Peninsula fitness pros leading charge on tax-deductible gym memberships

Live Well Exercise Clinic CEO Sara Hodson pitched idea to deputy prime minister

B.C. Health Minister Adrian Dix and provincial health officer Dr. Bonnie Henry head for the B.C. legislature press theatre to give a daily update on the COVID-19 pandemic, April 6, 2020. (B.C. government)
B.C. nears 300,000 COVID-19 vaccinations, essential workers next

564 new cases, four deaths, no new outbreaks Thursday

Shiromali Krishnaraj arrives from India and receives a mandatory COVID-19 test at Pearson International Airport during the COVID-19 pandemic in Toronto on Monday, Feb. 1, 2021. B.C.’s approved rapid tests also use a nasal swab, with a machine to scan for COVID-19 antibodies. THE CANADIAN PRESS/Nathan Denette
B.C.’s rapid COVID-19 tests have produced only two positive results

Tests deployed for exposures in schools, outbreaks in care homes, jails

BC Emergency Health Services confirmed that a call was received just before 10 a.m. Ground paramedics, as well as an air ambulance, are on the way to the area. (SUSAN QUINN/ Alberni Valley News)
BREAKING: Helicopter goes down on Bowen Island

Unclear how many passengers aboard and unclear where the helicopter was going

The Nanaimo bar display at the Nanaimo Museum. (City of Nanaimo Instagram)
City of Nanaimo points to correct recipe after New York Times botches batch of bars

City addresses ‘controversy’ around dessert square’s layers

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

A man holds a picture of Chantel Moore during a healing gathering at the B.C. Legislature in Victoria on June 18, 2020. THE CANADIAN PRESS/Chad Hipolito
B.C. First Nation demands transparency in probe into second fatal RCMP shooting

‘Police have killed more Tla-o-qui-aht First Nation members than COVID’

Hope’s station house, moved from its original location along the railroad to 111 Old Hope Princeton Way. (Emelie Peacock/Hope Standard)
Citizens file B.C. Ombudsperson complaint against Hope Council in Station House fracas

Demolition contract has been awarded, completed by April 30

Provincial health officer Dr. Bonnie Henry updates B.C. on the COVID-19 situation. (B.C. government)
Dr. Bonnie Henry predicts a ‘post-pandemic world’ for B.C. this summer

‘Extending this second dose provides very high real-world protection to more people, sooner’

The B.C. Supreme Court ruled Feb. 26 that the estate of deceased Sooke man and Hells Angels prospect Michael Widner is to be divided between his wife and his secret spouse. (Black Press Media file photo)
Estate of dead B.C. Hells Angels prospect to be divided between wife, secret spouse

Michael Widner’s 2017 death left a number of unanswered questions

Most Read