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Tromethamine In Pfizer-BioNTech Children’s COVID-19 Vaccine Improves Vaccine Stability; it is not included in the vaccine as a heart medicine



Pfizer-BioNTech’s COVID-19 vaccine for children contains tromethamine, “a heart attack drug” with “many potentially serious side effects”.


In fact inaccurate: Tromethamine is not a drug used to treat heart attacks. Rather, it is used to regulate acidity in body fluids in metabolic acidosis, which can result from a variety of medical conditions, including cardiac bypass surgery and cardiac arrest.
Missing context: Tromethamine has been used safely in many products, including the Moderna COVID-19 vaccine.


In October 2021, the U.S. Food and Drug Administration approved the emergency use of the Pfizer-BioNTech COVID-19 vaccine for children ages 5-11. The vaccine is suitable for children and contains one third of the adult dose. The children’s vaccine is also available in a slightly different solution that contains tromethamine. This new formulation improves vaccine stability and shelf life as the vaccine can be stored in the refrigerator longer than the original vaccine.

FULL DEMAND: “They replaced the salt buffer in the vaccine with a drug called tromethamine [..] This is a drug that is given to people who have had a heart attack. It is a blood acid producer. It has many potentially serious side effects. ”


On October 29, 2021, the U.S. Food and Drug Administration (FDA) approved the emergency use of the Pfizer-BioNTech COVID-19 vaccine in children ages 5-11. This vaccine for children has a slightly different formulation than the adult vaccine.

Claims the vaccine contains a potentially dangerous drug called tromethamine, which is distributed via social media platforms. An early repetition of that claim is this TikTok video, shared more than 22,000 times, claiming that tromethamine is “a drug given to people who have had a heart attack” with “potentially serious side effects.”

Similar claims about tromethamine’s function and side effects also surfaced on other social media platforms including Facebook, Instagram, Reddit, and Twitter (see examples here, here, and here) and on sites like American Faith. In total, these posts received more than 40,000 interactions, according to the CrowdTangle social media analysis tool.

As we will explain below, these posts are misleading as tromethamine is not a heart drug. Rather, it stabilizes the acid and alkalinity levels in liquids, and its role in COVID-19 vaccines is to allow the vaccine to be stored in the refrigerator for longer.

Tromethamine is a pH-regulating solution, not a drug used to treat heart attack

Pfizer-BioNTech has changed the pediatric vaccine formulation as described on page 14 of the information document. The new formulation is suitable for children and contains a lower dose of mRNA than the original adult vaccine. It also replaces the saline solution with tromethamine.

Tromethamine – also called tris – is a buffer, which is a liquid chemical mixture that regulates the acidity or alkalinity (pH) of solutions. Because it regulates pH, tromethamine can prevent and treat a condition called metabolic acidosis, which makes body fluids too acidic. Metabolic acidosis can have many causes, including cardiac arrest, cardiac bypass surgery, and childhood cancer. Contrary to what is claimed on social media, tromethamine does not treat these conditions. Instead, it reduces acidity to prevent organ damage while the patient gets the real treatment for the condition that caused the acidosis in the first place. Therefore, the claim that it is a “blood acid producer” is wrong, because the function of tromethamine is actually the opposite: to make body fluids less acidic.

Likewise, the role of tromethamine in the new vaccine formulation is not to prevent potential vaccine side effects, but to improve the stability of the vaccine itself by keeping the pH stable. According to the FDA briefing document, this new formulation extends the storage of thawed vaccine vials at a refrigerated temperature by up to ten weeks instead of the two weeks for the original formulation. Peter Marks, director of the Center for Biologics Evaluation and Research at the FDA, stated this in a press conference on October 29, 2021:

“We also approved a change in how the vaccine is made to include a formulation that uses a different buffer that helps maintain the vaccine’s pH, which is a measure of how acidic or alkaline a solution is, and their stability. This formulation is more stable over a longer period of time at chilled temperatures and allows vaccination providers greater flexibility. “

The new vaccine formulation with tromethamine is not just for children; it is also authorized and available to anyone aged 12 and over.

The tromethamine added to the vaccine does not affect its safety

Many posts like this claimed that tromethamine has potentially serious side effects, including “respiratory depression and IV”. [intravenous] Thrombosis “. This claim is highly misleading as it relates to patients receiving tromethamine for the treatment of metabolic acidosis. Such treatment involves the intravenous infusion of about half a liter of tromethamine several times during the illness. But even these cases are serious Side effects rare.

In contrast, the COVID-19 vaccine for children has a total volume of 0.2 milliliters per dose given intramuscularly. Although the new formulation was not used in the pediatric clinical study, this change is “not considered clinically significant” because many other products contain tromethamine without any associated safety issues. In fact, tromethamine is found in the Moderna COVID-19 vaccine and in several FDA-approved vaccines such as the Ebola and Dengue vaccines. The dengue vaccine is also approved for children aged nine and over. Peter Marks pointed out at the press conference:

“The new formulation contains tromethamine, known as Tris buffer, and is widely used as a buffer in a variety of other FDA-approved vaccines and biologics, including products for use in children. The manufacturing data evaluated by the FDA supports the change to this inactive ingredient and concluded that it had no effect on the safety or effectiveness of the product. “

Serious side effects of the COVID-19 vaccine are rare; the benefits of vaccination in children outweigh the potential risks

Some have claimed that the COVID-19 vaccination is of no benefit to children, as children are much less likely to develop severe COVID-19 and die than adults. While it’s true that children are at lower risk from COVID-19, some children still need to be hospitalized and a certain proportion will die.

The Advisory Committee on Vaccination Practices found that the United States Centers for Disease Control and Prevention (CDC) has recorded 8,300 hospitalizations and 146 deaths in children aged 5 to 11 years since the pandemic began. Amanda Cohn, chief medical officer for the Vaccine Task Force and the CDC’s National Center for Immunization and Respiratory Diseases, stated in an article in the New York Times that COVID-19 was “the eighth most common child killing in this age group in the past year “Was

Clinical study data show that the COVID-19 vaccine elicits a robust immune response in children and is 90.7% effective against symptomatic diseases. This means the vaccine could prevent the majority of hospitalizations and deaths in this age group.

Like any other medical intervention, COVID-19 vaccines can have side effects. However, most of these side effects are mild and temporary. Serious side effects, on the other hand, are rare. The most common adverse reactions observed in children during the clinical trial were injection site pain, fatigue, headache and muscle pain. Although the researchers did not see any serious side effects in children, the committee also considered the potential risk of heart inflammation previously reported in some vaccine recipients, especially young men.

Ultimately, the risk-benefit analysis of vaccination in children depends on the potential risks of the vaccine, its effectiveness and the incidence – the number of new cases that will emerge in the population in the near future. The FDA has considered six possible scenarios, including one with the lowest incidence. The Committee concluded that “the overall benefits of the vaccine may still outweigh the risks in this lowest incidence scenario”.

This benefit-risk profile would be even more favorable for vaccination if the risk of heart inflammation in children is lower than expected. This is a real possibility as myocarditis is generally less common in younger children than it is in adolescents[1]. Pediatric experts also suggest that the lower dose of the vaccine formula for children (10 micrograms) compared to the adult dosage (30 micrograms) might also reduce the risk of side effects.


Social media posts claiming tromethamine is a heart medication with potentially serious side effects are inaccurate and misleading. Tromethamine is not a heart drug and its presence in the vaccine is said to prevent rare cases of heart inflammation that have been reported in some COVID-19 vaccine recipients, some claimed. Instead, this ingredient acts as a stabilizer, allowing the vaccine to be stored in the refrigerator for longer.


This FactCheck.org article provides detailed information on the formulation of the Pfizer-BioNTech Pediatric COVID-19 Vaccine and the results of the clinical trial.



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