Is exposing babies to multiple vaccines in their first two years linked to an increased risk of children coming down with infections not targeted by vaccines?

No, finds a paper released today in The Journal of the American Medical Association (JAMA), that reports on a nested case control study that included 193 cases with non–vaccine-targeted infections and 751 controls without non–vaccine-targeted infections.

The authors concluded that “among children from 24 through 47 months of age with emergency department and inpatient visits for infectious diseases not targeted by vaccines, compared with children without such visits, there was no significant difference in estimated cumulative vaccine antigen exposure through the first 23 months of life.”

The findings are welcomed by Dr Helen Petousis-Harris, a vaccinologist and the Director of Research at the Immunisation Advisory Centre at the University of Auckland, because the study addressed a common concern among parents.

The concern that prompted the research dates back to a US survey in the late 1990s that found that 25% of parents thought that too many vaccines weaken a child’s immune system, and 23% thought children received too many vaccines.

While a range of studies had looked at the safety and efficacy of individual vaccines separately and in combination with others, the safety of the overall vaccine schedule had not been examined, and this schedule had evolved to include increased numbers of routine shots, from 8 in 1994 to 14 in 2010.

Too many too soon?

‘Too many too soon’ became a common refrain among anti-vaccine groups and in 2013, the Institute of Medicine (IOM), now the National Academy of Medicine, called for increased research into the safety of the entire childhood immunisation schedule.

In a linked editorial in JAMA, doctors Sean T. O’Leary and Yvonne A. Maldonado write that “pressure from anti-vaccine groups played no small role in shaping the IOM’s recommendation to study the overall schedule.”

“The IOM report stated ‘parents and healthcare professionals would benefit from more comprehensive and detailed information with which to address parental concerns about the
safety of the immunisation schedule,’” they write.

“Simply providing scientific information and assuming parents will make the decision to vaccinate is not enough.

“Delivering evidence-based information to parents and clinicians in ways that inspire confidence in the robust and safe childhood immunisation schedule is critical for maintaining the health of children,” they write.

Welcomed by NZ expert

Dr Helen Petousis-Harris said she was really pleased to see that the study has been done. “Not because there are scientific concerns about the safety of vaccines, but because it’s an issue that constantly comes up. It’s a very common idea that children’s immune systems might be compromised by the vaccine schedule,” she said.

“What’s also important to note is that this study looks at non-vaccine preventable infections, but of course children who have been vaccinated will be much less likely to have vaccine-preventable infections.

Dr Petousis-Harris believes such studies have two important functions.

“The first is to regularly examine and maintain our knowledge on the safety profile of vaccines. And the second is to address public concerns and perceptions,” she says.

The concern that multiple vaccines in early childhood could harm a baby’s immune system is a common one in New Zealand as well as the US.

“I would say that would be one of the top concerns among parents.

“There’s been some research capturing how people imagine the vaccines work to harm their children. So when you ask parents who have not fully vaccinated or chosen to opt out of the schedule, they find it difficult to articulate why, exactly.

“While we have always had an active anti-vaccine lobby in New Zealand, we now have social media and the internet creates the opportunity for instant dissemination of misinformation and ‘alternative facts.’

“Though at the same time, we now have the technology to be able to look at huge amounts of data and do bigger studies that show healthcare outcomes across the world, and this has become an incredibly valuable tool in assessing the power of vaccines.”

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