Pfizer-BioNTech COVID-19 Vaccine: Ingredients And My Symptoms Afterwards

I’m thankful I was in group 1A for my hospital system’s vaccine roll-out. I received my first dose of the Pfizer-BioNTech COVID-19 vaccine on December 18, 2020 followed by my second dose exactly three weeks later on January 8, 2021. In this post, I’ll discuss the ingredients and my symptoms following vaccination.


The Pfizer-BioNTech COVID-19 multiple dose vaccine vial contains a frozen suspension with the following ingredients:

  • Modified mRNA coding for SARS-CoV-2’s spike protein
  • Lipids: ((4-hydroxybutyl)azanediyl)bis(hexane-6,1-diyl)bis(2-hexyldecanoate), 2 [(polyethylene glycol)-2000]-N,N-ditetradecylacetamide, 1,2-Distearoyl-sn-glycero-3- phosphocholine, and cholesterol)
  • Salts: potassium chloride, monobasic potassium phosphate, sodium chloride, dibasic sodium phosphate dihydrate
  • Sucrose (table sugar)

This suspension is thawed either in a refrigerator or at room temperature. 1.8 cc of 0.9% sodium chloride (“normal saline”) is added as a diluent which, when combined with the aforementioned salts, creates a solution with optimum pH for mRNA stability. Each vial of the vaccine contains 5 doses of 0.3 cc. The lipid shell encapsulates the mRNA allowing it to be delivered into cells without early degradation.

The mRNA is utilized by normal cellular machinery (ribosomes, tRNA, etc.) to synthesize the spike proteins which are presented on the cell surface eliciting an immunologic response via antigen presenting cells, T helper cells, B cells, etc. Remember, these mRNA vaccines do NOT contain SARS-CoV-2, and therefore, cannot give you COVID-19. They also cannot alter your genetic makeup.


On December 18th, I was on call in the OR and received the vaccine around 12:30 PM. I went on with the work day but noticed my arm starting to get sore around 5:00 PM, and I felt a bit warm. By the time I went home that evening around 9:00 PM, my arm was a bit more sore. I didn’t have any issues overnight (nor was I called in, lol), and by the next morning, I was asymptomatic.

On January 8th, I had my second dose at 8:30 AM after giving a lecture to my fellows. I had come off a long week on service as an intensivist in a COVID-ICU, so I was particularly exhausted that day. Around 4 PM, I started having mild arm soreness in the site of injection. By 8:00 PM, this soreness got worse. I went to bed around 11:30 PM, but woke up at 1:00 AM with fever, headache, myalgias, weakness, and shivering that lasted for a few hours. I ended up taking 1,000 mg of Tylenol. I woke up at 5 AM, still had mild myalgias, a headache, and a subjective mild fever, but felt better after another dose of Tylenol.

CDC COVID-19 Vaccination Record Card

What symptoms did you have? Which vaccine did you take? Drop me a comment with your experience regarding COVID-19 vaccination!

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  1. Just got my second Moderna dose this past Saturday (4/3/2021) after getting the first back on March 6th. In both rounds, I had the chills and a headache plus arm stiffness the day or two afterward. I’ve been monitoring a slight chest pain I’ve had with the second dose, as I do hope that goes away soon!

  2. As you have asked: I also received two doses of the Pfizer vaccine, coincidentally on the same dates as you. I am an estimated 25 years older than you; from what I have read, younger individuals in general have more profound reactions to the vaccine compared with older individuals.

    I too developed severe arm pain several hours after the first vaccine dose. By the next day, my arm was sufficiently sore that I could not easily raise it above shoulder level, nor could I lie on that shoulder in bed. It took about 28 hours for the soreness to completely resolved.

    Following the second dose, which I received at 8:15 AM, I felt well for most of the day, and had no trouble completing my cases for the day. However, by evening I began to feel mild chills and my shoulder had again become sore, again such that I could not raise it above shoulder level or lie on it. The following day I had a moderately severe headache and diffuse myalgias, and felt chilled; symptoms essentially like having a flu-like syndrome. Although I felt chilled, I did not have objective fever. I was also quite fatigued and took a 3 hour nap in the afternoon. By this morning I was markedly better although still with a mild headache which has improved through the day. Myalgias are present but mild and at this point, nearly 60 hours after the second dose, I am pretty much back to “normal.”

    Certainly more symptoms than I would typically get each year from the flu vaccine, but a very small price to pay for what will hopefully be some protection from getting COVID19. We can only hope that enough vaccines can be administered that we can develop the herd immunity necessarily to stop this pandemic.


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