COVID-19 And ‘The Vaccine’

January 31, 2021 | COVID-19, Drug Allergy

     As 2021 starts, COVID-19 continues.  But, so does the rollout of the two vaccines—one from PfizerBioNTech and one from Moderna– that have been developed from the messenger RNA (mRNA) of the SARS-CoV-2 virus.   The PfizerBioNTech vaccine is under emergency use authorization (EUA) for those 16 and older.  The Moderna vaccine is under EUA for those 18 and older.  We have heard that these two mRNA vaccines are 94-95% effective, based on comparing the occurrence of COVID-19 between those who received the vaccine and those who received placebo during the two months after the booster.  

     There are many topics that could be discussed about the vaccine.   This blog will be mainly about those with allergic conditions and questions that are coming up in relation to those conditions.  The information below that does come from the CDC website about the mRNA vaccines was last updated on January 21st.

Who Should Not Get The mRNAVaccine?

  • Those who have a known history of a severe allergic reaction to any component of the mRNA COVID-19 vaccine.  “Severe,” such as anaphylaxis, means the person needed to be treated with epinephrine or had to go to the emergency room because it was an allergic reaction—not a vasovagal reaction.  Allergic can include any of the following: hives; swelling of the mouth/lips/tongue/throat; shortness of breath, wheezing or chest tightness; low blood pressure or loss of consciousness.
  • Those who had a severe allergic reaction to the 1st dose of the mRNA COVID-19 vaccine.
  • Those who had an immediate allergic reaction to the 1st dose of the mRNA COVID-19 vaccine. “Immediate” is being defined as starting within 4 hours of being injected with the dose. 
  • Those who had a previous immediate allergic reaction of any severity to any component of the mRNA vaccine (including a substance called polyethylene glycol…PEG for short).  PEG has not previously been used in a vaccine. It is used in several laxatives (e.g. Miralax), bowel preps pre-colonscopy (e.g GoLytely), some processed foods, cosmetics and other drugs. 
  • Those who had a previous immediate allergic reaction of any severity to polysorbate.  Polysorbate is a substance that is similar in its chemical structure to PEG and is in many medications and vaccines (e.g. Shingrix).  Reactivity to only polysorbate is considered to be rarer than to PEG.

     Of these vaccine components, it is the two lipids mentioned above—PEG and polysorbate—that would likely be the issue.  The salts, sugars and buffers in these vaccines are not considered to be significantly allergenic.  The CDC notes that an allergist/immunologist could evaluate a person who had an immediate allergic reaction and determine if the person could safely receive the vaccine. But, the vaccine would have to be given in a setting with advanced medical care available and under observation for some prolonged period of time than just 15 minutes—the current standard waiting period after receiving the vaccine.

Can I get the mRNA vaccine if I had any of these allergic conditions:

A history of a severe or immediate allergic reaction to any other vaccine without the components of the mRNA vaccines?

     The CDC considers this situation to be a precaution instead of a ‘no’ (i.e. contraindication). Finding out whether the vaccine had PEG or polysorbate or another substance called polyoxyl 35 should be attempted.  The CDC recommends discussing the appropriateness of receiving the mRNA vaccine in the context of factors such as (a) risks for severe disease or death based on one’s age and underlying medical conditions, (b) risk of exposure to the virus because of occupation and residence in a congregate setting such as a long-term care facility and (c) prior infection with SARS-CoV-2 and opting to wait for more information about risk of anaphylaxis from the mRNA vaccines. 

     If the decision is to go ahead with the mRNA vaccine, then the observation period after the vaccine in the facility should be 30 minutes. 

A history of a severe or an immediate allergic reaction to an injectable medicine?

     The answer is the same as the one above about any other vaccine without the components of the mRNA vaccine.

A history of a severe allergic reaction to a food, pet or venom?

     Yes, one can receive the mRNA vaccine but the observation period after the vaccine in the facility should be 30 minutes.

A history of a severe allergic reaction to latex?

     Yes.  The vial stoppers of the mRNA vaccines are not made with natural rubber latex   Latex is not a component of the mRNA vaccine.  The CDC still advises a 30-minute observation period for anaphylaxis from any cause. 

Can I get the mRNA vaccine if I have any of these conditions:

An immunocompromising condition?

     Yes, as long as there is no contraindication to vaccination.  However, data are not currently available to establish safety and effectiveness in this group.  It is also unknown about the degree of immune response to the vaccine.  The need still continues, for now, to follow the physical recommendations we have been used to for close to a year.  Antibody testing is not recommended to assess for immunity to COVID-19 after receiving the mRNA vaccine. 

An autoimmune disease (e.g. scleroderma or ‘lupus’)?  

     Yes, although no data are currently available on the safety and effectiveness of mRNA vaccines in individuals with this type of condition. 

     Some encouraging news is that immediate allergic (i.e. anaphylactic) reactions to these mRNA vaccines may be decreasing.  The initial report earlier this month was that the occurrence of these reactions from the PfizerBioNTech product  is 11 per million individuals.  On January 27th, the CDC now reports that the frequency of anaphylaxis through January 18th has decreased to 5 per million doses. The frequency from the Moderna vaccine is still essentially between 2.5 and 3 per million doses through January 10th.  As a point of reference, the rate of allergic reactions to vaccines in general is 1.3 per million doses with no fatalities, based on a large population-based study published in 2016 in the Journal of Allergy and Clinical Immunology.  In that publication, slightly higher frequencies were observed in females, but rates were similar across ages.

   I urge people to look carefully, and at least weekly, at the CDC website to read more about the mRNA vaccine as we learn together and live together through this.  The CDC website support page is       

Dr. Klein