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The U.S. Food and Drug Administration (FDA) expanded its approval of Merck’s pneumococcal vaccine Capvaxive for use in children ages 2 and up who are considered at increased risk for the disease.
The drug was specifically designed for adults, Merck said in a statement, but “may” offer additional protection for high-risk kids.
Critics pointed out that the vaccine adds to the list of childhood vaccines not tested against a placebo, and that it contains an ingredient linked to high rates of adverse events.
Children and teens with chronic conditions, including pneumonia, meningitis and bloodstream infections, can get the vaccine in addition to the pneumococcal conjugate vaccine (PCV) they already get as part of routine pediatric shots recommended by the Centers for Disease Control and Prevention (CDC).
The decision makes Capvaxive the only PCV approved as an extra vaccine for this group.
The vaccine protects against Streptococcus pneumoniae, which causes a wide range of bacterial infections, including pneumonia, bacterial meningitis and middle ear infections. The illnesses are typically treated with antibiotics.
CRM197: a questionable platform for childhood vaccines
The FDA based its expanded approval of the drug on results from a Phase 3 trial that enrolled 882 children and adolescents with chronic conditions.
The trial compared Capvaxive against PPSV23 (pneumococcal 23-valent polysaccharide vaccine), another vaccine that protects against pneumococcal illness — meaning it was not tested against an inert placebo.
Capvaxive contains CRM197, a protein. It is a mutant of the diphtheria toxin used to boost the immune response in some vaccines. In Capvaxive, bacterial sugars from 21 strains of pneumococcus are individually linked, or conjugated, to the CRM197, which enhances the body’s immune response to each of the bacteria.
Children’s Health Defense (CHD) Chief Scientific Officer Brian Hooker warned that giving a vaccine containing CRM197 to at-risk kids will be “another train wreck for children, but a boon for Merck as it opens up a fresh new market of children.”
That’s because research has found that other vaccines using the platform have high rates of adverse events.
The diphtheria toxin is a protein that enters a cell and destroys the cells around it, allowing diphtheria to proliferate. This is what made it a very dangerous illness in the early part of the 20th century.
In the 1970s, Harvard researchers figured out how to mutate the instructions that produced the toxin to eliminate its toxic effect, CHD Senior Research Scientist Karl Jablonowski told The Defender.
“This new protein gave biologists an amazing tool, a ‘carrier protein.’ Scientists can now bind something to the protein, and that something will be ‘carried’ into the cell,” he said. “It is an absolute necessity for our understanding of cellular biology.”
Researchers named that protein Cross-Reacting Material 197, or CRM197.
However, Jablonowski said, “A terrific cellular biology tool is a questionable platform for childhood vaccines.”
Capvaxive contains ingredient used in HibTITER shot pulled from market in 2007
In 2024, Jablonowski and Hooker published an analysis of the thimerosal-free HibTITER pediatric vaccine marketed by Wyeth from 2003 through 2007, when it was pulled from the market. HibTITER was the first CRM197 vaccine approved in the U.S., Jablonowski said.
They found that the HibTITER vaccine, made with CRM197, was associated with 19 different medical conditions. The conditions include life-threatening side effects at rates “significantly higher” than other Haemophilus influenzae type B or Hib vaccines.
They did not definitively link the toxicity of the vaccine to CRM197, Jablonowski said. However, they hypothesized that this could be what made the vaccine so toxic to young children.
Jablonowski said that CRM197 vaccines have never undergone a placebo-controlled randomized study in children. Only one such study was conducted in adults 65 and older, and the vaccine was found to have an “acceptable safety profile.”
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Earlier childhood PCV vaccine with CRM197 also not tested against placebo
An earlier version of the PCV vaccine given to children, called Prevnar (PCV7) — later replaced by a shot that addressed more strains of the illness — also used CRM197.
When the vaccine was tested in the 1990s, the investigators argued that doing a placebo-controlled study was unethical, because study participants would have to receive four shots with no potential for benefit.
Jablonowski said that even if they didn’t want to use an inert placebo, the researchers could have chosen many other options for a comparison that would have bestowed benefit on the control group.
However, they chose another vaccine that also used CRM197 as the comparator shot for the study. That vaccine was also made by Wyeth, which sponsored the study.
A small percentage of children in both groups experienced adverse events, ranging from injection site swelling to febrile seizures to SIDS (sudden infant death syndrome).
However, it was impossible to detect whether there was a safety signal related to CRM197, because both groups received vaccines that contained the toxin.
Jablonowski said the trial “demonstrated the absurdity of our arrogance when it comes to safety studies,” because “when it came to the safety of CRM197, the study was either not designed to detect a signal or designed to not detect a signal.”
Related articles in The Defender
- Despite Concerns About ‘Vaccine Fatigue,’ CDC Recommends Extra COVID Boosters, Including for Some Infants
- RFK Jr. Rips CNN Over Claims on Vaccines and Placebo-Controlled Trials
- Vaccine ‘Quietly’ Pulled Off Market in 2007 Now Linked to 19 Diseases — 35 Million Babies Who Got the Shot Now at Risk as Adults
