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

Dr. Bonnie Henry, provincial health officer, updates British Columbians about COVID-19 at a press conference earlier this week. (B.C. Government image)
B.C.’s 1st case of COVID-19 confirmed a year ago today

Here’s a look at some of the key dates in the province’s fight against the novel coronavirus

Toronto’s Mass Vaccination Clinic is shown on Sunday January 17, 2021. THE CANADIAN PRESS/Frank Gunn
Interior Health reports 2 more deaths, 83 new COVID-19 cases

Health authority also identifies new virus cluster in Fernie

Syringa Provincial Park is popular camping destination. Photo: Betsy Kline
Water upgrades coming at Syringa Provincial Park

Upgrades at the popular camping and day-use park will be ready for 2021 reopening

South Columbia Search and Rescue called in the Nelson Search and Rescue and Kootenay Valley Helicopters to provide a long line rescue. Photo: BCSAR submitted.
Long-line rescue needed for injured hiker near Trail

Members of South Columbia and Nelson SAR and Kootenay Valley Helicopters did a long-line evacuation

A sign indicating a COVID-19 testing site is displayed inside a parking garage in West Nyack, N.Y., Monday, Nov. 30, 2020. The site was only open to students and staff of Rockland County schools in an effort to test enough people to keep the schools open for in-person learning. (AP Photo/Seth Wenig)
4 more deaths, 54 new cases of COVID-19 in Interior Health

This brings the total to 66 deaths in the region

British Columbia Health Minister Adrian Dix looks on as Provincial Health Officer Dr. Bonnie Henry addresses the media during a news conference at the BC Centre of Disease Control in Vancouver B.C. (THE CANADIAN PRESS/Jonathan Hayward)
B.C. announces 485 new COVID-19 cases, fewest deaths in months

‘The actions we take may seem small, but will have a big impact to stop the virus,” urges Dr. Henry

Grad student Marisa Harrington and her supervisor Lynneth Stuart-Hill say preliminary results from a study into the affects of stress on hospital nurses show an impact on sleep and heart variability. (Courtesy of Marisa Harrington)
University of Victoria study shows stress impact on B.C. nurses

Stress may be impacting sleep, heart health of hospital nurses in Victoria region

Keith Thorpe/Peninsula Daily News
Search called off for small plane that went down in rough water south of Victoria

Plane bound for Port Angeles from Alaska believed to have one occupant, an Alaskan pilot

Royal B.C. Museum conservator Megan Doxsey-Whitfield kneels next to a carved stone pillar believed to have significance as a First Nations cultural marker by local Indigenous people. The pillar was discovered on the beach at Dallas Road last summer. Museum curatorial staff have been working with Songhees and Esquimalt Nation representatives to gain a clearer picture of its use. (Photo courtesy Royal BC Museum)
Stone carving found on Victoria beach confirmed Indigenous ritual pillar

Discussion underway with the Esquimalt and Songhees about suitable final home for the artifact

Former Vancouver Giants forward Evander Kane is seen here in Game 7 of the second round of the 2009 WHL playoffs against the Spokane Chiefs (Sam Chan under Wikipedia Commons licence)
Gambling debts revealed in details of bankruptcy filing by hockey star Evander Kane

Sharks left winger and former Vancouver Giants player owes close to $30 million total

Othman “Adam” Hamdan, pictured in front of Christina Lake’s Welcome Centre, was acquitted of terrorism related charges in 2017. He has been living in Christina Lake since November 2020. Photo: Laurie Tritschler
Man acquitted on terrorism charges awaits deportation trial while living in Kootenays

Othman Ayed Hamdan said he wants to lead a normal life while he works on his upcoming book

B.C. Premier John Horgan wears a protective face mask to help prevent the spread of COVID-19 prior to being sworn in by The Honourable Janet Austin, Lieutenant Governor of British Columbia during a virtual swearing in ceremony in Victoria, Thursday, November 26, 2020. THE CANADIAN PRESS/Jonathan Hayward
Premier Horgan calls jumping COVID vaccine queue ‘un-Canadian’

Horgan says most people in B.C. are doing their best to follow current public health guidelines

Prime Minister Justin Trudeau, left, and Vancouver Mayor Kennedy Stewart share a laugh while speaking to the media before sitting down for a meeting at City Hall, in Vancouver, on Friday August 30, 2019. (THE CANADIAN PRESS/Darryl Dyck)
Vancouver mayor, Health Canada to formally discuss drug decriminalization

Kennedy Stewart says he’s encouraged by the federal health minister’s commitment to work with the city

Royal Inland Hospital in Kamloops. (Dave Eagles/Kamloops This Week file photo)
COVID-19 outbreak at Kamloops hospital grows to 66 cases

A majority of cases remain among staff at Royal Inland Hospital

Most Read