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Experts say the best protection against measles for infants is for everyone around them to be vaccinated. Getty Images
  • A new study reports that the measles immunity transferred from a mother to her newborn child may last for only 3 months.
  • Experts say that leaves infants vulnerable to measles before they get their first vaccination at 1 year old.
  • Experts say they don’t expect the childhood vaccination schedule to change.
  • They say the best protection is for adults and older children around the baby to be vaccinated.

A mother protects her child from so many things during infancy — one of them being measles.

That’s because maternal antibodies transferred during pregnancy can shield a newborn child from this infection.

Now, research published today in the journal Pediatrics suggests this shared immunity may wane by 3 months of age, not 1 year as previously thought.

It’s an eye-widener for parents, for sure, but experts say not much will change for infants based on these findings.

In this study, researchers measured protection from measles in infants less than 1 year of age who were being cared for at The Hospital for Sick Children in Toronto, Canada, between 2014 and 2016.

The researchers reported that 20 percent of 1-month-old infants had antibody levels that were below the protective threshold.

However, 92 percent of 3-month-olds were below this threshold.

What’s more, all of the infants lacked sufficient measles immunity by 6 months of age, based on antibody levels.

The researchers said they were surprised by their findings, since before this research it was generally assumed infants were immune for at least the majority of their first 6 months of life.

“Since infants are immunized routinely at 12 months in Ontario, Canada, our findings have revealed a wide susceptibility gap between the time that infants lose the protection that they’ve received from their mother and when they are protected by vaccination at 12 months,” Shelly Bolotin, PhD, MS, a scientist with expertise in immunity at Public Health Ontario and co-lead of the study, told Healthline.

In the United States, which saw a historic measles comeback this year, and many other countries, including Canada, the measles, mumps, and rubella (MMR) vaccine is routinely given starting at 12 months of age based on the risk of measles infection and the ability of an infant’s immune system to respond to the vaccine.

“Since infants are at higher risk of complications from measles infection (including pneumonia and encephalitis) and death, our results highlight the risk in this age group and the need to protect infants from measles by ensuring that those around them are vaccinated,” Bolotin added.

William Schaffner, MD, an infectious disease specialist at the Vanderbilt University School of Medicine in Tennessee, agrees that the biggest takeaway here is that it reinforces the importance of vaccinations.

“Because the best way to protect infants who are at very high risk of the complications of measles is to have everyone else vaccinated and to surround them with protection,” Schaffner told Healthline.

Sean O’Leary, MD, a pediatrics infection disease specialist at Children’s Hospital Colorado, concurs.

“We need to maintain high vaccination levels in the community to keep this from being an issue,” O’Leary, who’s also a member of the American Academy of Pediatrics’ Committee on Infectious Diseases, told Healthline. “If we have high vaccination rates across the world, the U.S., and Canada, etc., this won’t be an issue.”

Neither doctor thinks the study will have an impact on the current vaccination schedule, which is set by the Centers for Disease Control and Prevention (CDC) based on the Advisory Committee on Immunization Practices (ACIP) recommendations.

Typically, one study doesn’t lead to a change in the schedule, says O’Leary.

He notes that the phenomenon of waning immunity has been known for some time, and the schedule hasn’t changed.

“It won’t change the way we vaccinate, I think, because by reducing the age at first vaccination — we start now at 12 months of age — you reduce the effectiveness of the vaccine,” Schaffner said. “And nobody wants to add that uncertainty. I think it is very unlikely that ACIP will change its recommendations regarding the age at first vaccination with MMR.”

O’Leary explains that the vaccine contains a weakened version of the measles virus, and in order to work, it has to replicate in the body.

“So, if you give it to a very young infant who has a lot of maternal antibody on board from pregnancy and delivery, before that antibody has worn off, that infant’s antibodies from the mom are going to keep the live, weakened virus from reproducing in the body,” he said. “It’s that reproduction in the body that leads to long-term immunity.”

So, as a parent, how should you proceed?

The researchers encourage parents to follow the vaccination schedule in their jurisdiction.

“However, if parents are planning to travel to a country where measles is endemic (i.e., is circulating), we encourage them to consult with their healthcare provider prior to traveling, given that measles is one of the most infectious diseases,” Michelle Science, MD, MSc, co-lead on the study and an infectious diseases physician at The Hospital for Sick Children, told Healthline.

“In Canada and the U.S., infants may receive a dose of measles vaccine as early as 6 months of age if they will be traveling to an area where measles is circulating,” she added.

The recommendation is for parents to vaccinate according to the recommended schedule for all diseases, O’Leary says. But stay abreast of what’s happening near you or in places you travel, and consult with your child’s doctor.

“In certain outbreak situations they are going to recommend giving the vaccine at an earlier age. Currently, if you travel internationally, it’s recommended to give the vaccine as young as 6 months. It has to be repeated at a year, so it doesn’t count as a dose but just to offer potential protection,” O’Leary said.

“That’s similar if there’s an outbreak somewhere in the U.S. Local or state public health [officials] will sometimes make recommendations to vaccinate at a younger age, but they still need to get revaccinated later,” he said.

It’s important to recognize that babies aren’t born in isolation, and that vaccinating yourself and others who surround your baby, including older siblings, is the best defense.

“MMR is safe and is among the most successful vaccines we have, particularly as regards to measles,” Schaffner added. “It’s remarkably successful.”