COVID-19 vaccine allergy

  • by VaccineHealthCenter

Health agencies have done their best in coming up with vaccines that offer the body protection against Covid-19 infection. While some people might be enthusiastic about the vaccines and readily go for them, there is a group that is skeptical and will never think of getting the vaccines. Part of this camp has its skepticism arising from the allergic reactions that some vaccinated people reported. Between the 14th and 20th of December 2020, the first lot of people went for the vaccine. Out of the 1,893,360 vaccinated cases, the Vaccine Adverse Event Reporting System reported that 21 cases had an allergic reaction. This has scared many people, among whom the skeptical type arises.

What is the Covid-19 vaccine allergy?

The 21 people reported an allergic reaction known as anaphylaxis. Anaphylaxis refers to a life-threatening hypersensitive reaction of the body to allergens such as food, medication, pollen, venom, and dust. Under normal circumstances, foods such as peanuts and tree nuts are known to cause anaphylaxis. However, last year, the medical sector reported anaphylaxis in those who received Covid-19 vaccines.

Signs of Covid-19 vaccine allergy

The people who reported anaphylaxis after taking the Covid-19 vaccine had the following symptoms;

  • Pain in the abdomen
  • Feelings of confusion, anxiety, and indecisiveness
  • Swelling of mouth, nose, and face
  • Constant shock
  • Eating problems such as hardship in swallowing food
  • Breathing issues characterized by wheezing
  • Itching of the skin
  • Speech problems especially slurred speech
  • Constant nausea
  • Skin developing rashes

What causes the Covid-19 vaccine allergy?
As a doctor, patients may ask you why they experienced the allergic reaction after taking the vaccine. The main reason is that the human system has a mechanism of defending itself against foreign invasive substances by producing immunoglobulins to fight the foreign substance of invader. However, this reaction should only be limited to foreign invaders and should not involve the body resisting itself. In the case of anaphylaxis, the body gets the very protective mechanism wrong. It interprets the Covid-19 vaccine as a foreign invader and it reacts hyper-sensitively to the vaccine. Because the vaccine is not an invader, the body is essentially fighting itself, resulting in a life-threatening reaction called anaphylaxis.

Could there be a component of the vaccine that triggers anaphylaxis
Because the vaccine itself is not an issue, it is prudent to know the specific element of the vaccine that triggers vaccine allergy. Breaking down each of the vaccines gives insight into this.

  • The Pfizer BioNTech COVID-19 vaccine- this is an mRNA vaccine that uses naturally occurring substance to enzymatically and chemically produce the vaccine's building components. In this vaccine, there is no virus usage. The ingredients consist of Potassium chloride, Monobasic potassium, Phosphate, Sodium chloride, Dibasic sodium phosphate dehydrate, Sucrose, and other ingredients in minute compositions.

  • Johnson & Johnson’s COVID-19 vaccine- unlike Pfizer, Johnson & Johnson’s uses a viral vector, especially the adenovirus type, to form the vaccine. The vaccine has the following ingredients besides the viral vector, Citric acid monohydrate, Sodium chloride, (2-Hydroxypropyl)-β-cyclodextrin, Trisodium citrate dehydrate, Ethanol, and Polysorbate-80.

  • Moderna COVID- 19 vaccine- this vaccine uses the same technology used in Pfizer, and uses mRNA instead of viruses. Its ingredients include mRNA, Tromethamine hydrochloride, Lipids, and Fatty acids, Sodium acetate, sucrose, Tromethamine, and Acetic Acid.

For all these Covid-19 vaccines, polyethylene glycol (PEG) is an ingredient that is used in vaccine manufacture. This could be the causative agent for anaphylaxis after taking Covid-19 vaccines. This is not clear though and some reactions might have a different mechanism as the causative agent, but this is unclear.

What should people with vaccine allergies do regarding the Covid-19 vaccine allergy?

If a patient tells you that he has had a past history of vaccine allergy or anaphylaxis when he takes some food or is stung by a venomous insect, it is prudent to work with the following CDC guidelines;

  • Screen the patient for precautions and contraindications
  • Get ready the services and materials for managing anaphylaxis
  • Follow the post-vaccination observation periods suggested by the health agents
  • Use intramuscular epinephrine injection on a suspected anaphylaxis case

People who are extremely scared of the vaccine need not have it as anaphylaxis is a life-threatening reaction.


Adverse Event Reporting System reported 21cases of anaphylaxis following the Covid-19 vaccine administration. This is like 11.1 cases per every million individuals. This article looked at the signs of Covid-19 vaccine allergy in people, the breakdown of vaccine components, the likely causative agent, and how to administer the patients with a history and a real case of anaphylaxis.