My Personal Experience With the Pfizer Vaccine

Kathryn H. Dao, MD


January 22, 2021

On October 31, 2020, I enrolled in the phase 3 trial of the Pfizer/BioNTech mRNA vaccine against SARS-CoV-2 (protocol C4591001). People asked why I did it, being that there were not much data on the vaccine's efficacy at that time. I gave them the answer that many of us have felt but have not voiced: I am tired. I am tired of seeing friends and colleagues get sick; I am tired of virtual learning for my children; I am tired of not being able to visit my mom and hug her; I am tired of this pandemic.

When given the chance to help end the pandemic, I volunteered. I have been an investigator and conducted many clinical rheumatology studies over the past two decades, but I never have been a study subject until now. I wanted to document my experience and allay fears about the vaccine and the clinical trials process.

I understand how clinical trials are conducted; before any investigational product can be made available to the public, it undergoes rigorous scrutiny by the US Food and Drug Administration (FDA), particularly by the main consumer watchdog in the system, the Center for Drug Evaluation and Research. With the urgency of the pandemic, the process is even more intense.

I Did My Research on the Process, the Vaccine, and the Study

The National Institutes of Health and its foundation for the first time brought together multiple organizations, including biopharmaceutical companies, the Centers for Disease Control and Prevention, the Health and Human Services' Office of the Assistant Secretary for Preparedness and Response, and the European Medicines Agency to prioritize drugs and vaccine candidates, streamline clinical trials, coordinate regulatory processes, and leverage assets to rapidly respond to COVID-19. So, when presented with the opportunity to participate in a clinical study evaluating a vaccine's effectiveness, I knew that this was an important step to get us closer to the end of the pandemic.

The Pfizer/BioNTech study would enroll 44,000 participants, and the Dallas study site needed one more person to complete its goal of enrolling 500 people. I became subject number 500. Participants were blinded to randomization; there was a 50% chance that I would receive saline without adjuvants/preservatives or the BNT162b2 vaccine candidate, in two doses separated by 21 days.

The vaccine contains modified segments of the virus's messenger RNA (mRNA), which utilizes the body's cell components to produce the spike protein seen on the coronavirus. Our own immune systems would then detect these spike proteins and start manufacturing the antibodies to them. The viral mRNA would then degrade without harming host cells. There is no risk for infection with the virus or insertional mutagenesis. The mRNA technology, developed over the past couple of decades, is emerging as a promising alternative to conventional vaccines with better efficacy and immunogenicity. I had done my research on this vaccine; I was ready.

I Learned From My Experience

When I arrived at the study site, my temperature was 98.4° F. I reviewed and signed the consent form with the investigator. The study staff took urine and blood samples and a nasal swab to test for the coronavirus. The clinical research coordinators were knowledgeable and efficient. After the negative results of my urine pregnancy test, I was taken to a back room to receive my first dose of the study injection.

The study vaccine was administered into my left arm; I had no pain, bruising, or even a dot to show where the needle entered. I felt deflated because I thought I'd received the placebo. Participants were sent home with an electronic diary to record their symptoms; this included an oral thermometer and a nasal swab for home testing. I thanked the study team and drove home.

The study required regular follow-up and blood draws for up to 26 months. Its endpoint was to have 164 cases of COVID-19 among trial participants to be able to evaluate the efficacy of the vaccine. Primary outcome measures include local reactions, adverse events, and hematologic/chemistry assessments. Secondary outcomes include the presence of SARS-CoV-2 neutralizing antibody and/or confirmed COVID-19 infection.

Eight hours later, my left arm started to throb; I saw that the site of injection was mildly warm, red, and swollen. A low-grade temperature of 99.4° F and slight myalgias ensued 2 hours later. I did not want to take any anti-inflammatories or acetaminophen, as I wanted to see what would happen. I didn't sleep well that night, with my left arm hurting and a low-grade headache developing. By morning, my temperature had risen to 100.4° F. I took 400 mg of ibuprofen and had a significant improvement in symptoms. I did have to take scheduled ibuprofen every 8 hours for the next 24 hours to subdue my symptoms, but soon I felt like my usual self.

After reading about others' bad experiences with the second dose, I was a little apprehensive. I returned for my second injection 3 weeks later, complying with study protocol, but I decided to take ibuprofen prophylactically before the vaccination and every 8 hours as needed. This worked. My arm was sore but not as bad; it felt more like a tetanus shot than a shingles vaccine. I slept through the night, my fever reached 100.3°F, and headaches occurred when I was due for my next dose of ibuprofen. I switched to acetaminophen and found that this controlled my fever but did not help my sore arm as much. I improved daily, and by the fourth day I felt amazingly well and had more energy. Relief washed over me; I did not anticipate this feeling. It was a glimpse of the end of the pandemic.

When Pfizer announced the success of the vaccine trial, I was elated. They had enrolled more than 44,000 participants. One hundred and seventy confirmed cases of COVID-19 were reported; all primary efficacy endpoints were met, and analysis of the data showed an efficacy rate of 95% (P < .0001) in participants without prior SARS-CoV-2 infection. One hundred sixty-two cases of COVID-19 were seen in the placebo group vs eight cases in the BNT162b2 vaccine candidate; nine out of 10 severe COVID-19 cases occurred in the placebo arm of the study. Efficacy was seen across all ages, genders, races/ethnicities; in adults over 65 years old, efficacy was > 94%. The Data Monitoring Committee found no serious safety concerns with the vaccine. The advisory panel for the FDA met on December 10, 2020, and voted 17-4 to endorse emergency use authorization (EUA) of the vaccine for Americans.

Confronting Vaccine Hesitancy

The news was exciting, but I became dismayed when I read that many people are unwilling to be vaccinated. Some news media focused on the side effects of the vaccine rather than the incredible efficacy; the data presented at the FDA hearing noted that injection-site reactions were seen in 84.1%, fatigue in 62.9%, headaches in 55.1%, muscle pain in 38.3%, chills in in 31.9%, joint pain in 23.6%, and fever in 14.2%. In my opinion, these are minor inconveniences compared with the devastation of acquiring COVID-19. I also worried about the misinformation being touted on antivaccination platforms.

In order to achieve herd immunity, more than 75% of people need to have effective antibodies. According to the World Health Organization, herd immunity against measles requires about 95% of a population to be vaccinated; for polio, the threshold is about 80%. The threshold for SARS-CoV-2 remains to be seen, but I advocate for a higher percentage of people getting immunity through vaccination than through infection.

In a study by the Yale School of Medicine published in The Lancet's EClinicalMedicine, only 67% of individuals surveyed plan to get vaccinated. The disparity was seen in race, education level, employment, and age, where more college-educated, employed, and older people (> 55 years of age) were willing to receive the vaccine. Eighty-one percent of Asian Americans vs 40% of Black Americans were willing to be vaccinated.

There is lack of communication and time spent to inform people of color about the benefits of vaccination and to answer their questions. Many fear the medical system and risk of "experimentation," and may not have the resources available to them to address their concerns due to the intrinsic bias in our system.

As healthcare professionals, we have a duty to take care of our patients, weighing risks and benefits to any therapies before we prescribe them. Vaccines are, by far, the greatest medical developments and have saved the most lives. In 2019, opposition to vaccines amplified the measles outbreak. And with the political climate, too many individuals have been confused and mistrustful about what is real or fake.

We healthcare professionals are in a unique position. We have a relationship with our patients, we have the knowledge, and we have the ability to change the course of the pandemic. As it stands, the number of people hospitalized for COVID-19 is rising; hospitals are strained, and people are dying due to inability to access adequate care. With this knowledge, I ask you: Do you want the vaccine or the disease?

Disclaimer: This is my personal experience and may not be what others experience when they receive the vaccine. Once the vaccine becomes available to the public, it is best to consult with your physician on whether the vaccine is appropriate for you and how to manage any side effects to the vaccine that may occur.

Kathryn H. Dao, MD, is an associate professor in the Department of Internal Medicine's Division of Rheumatic Diseases at the University of Texas Southwestern Medical Center in Dallas, Texas. Additionally, she is a contributing author and blogger for RheumNow.

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