Understanding COVID-19 Vaccines

June 28, 2021

Jennifer Wild, D.O.

Currently, COVID-19 vaccines from Pfizer, Moderna, and Janssen/Johnson & Johnson are available under the United States Food and Drug Administration (FDA) Emergency Use Authorization (EUA), which allows the vaccines to be used during a public health crisis while research is ongoing to seek formal approval. The new vaccines have sparked many questions about the vaccine delivery methods, efficacy, and side effects that may be encountered.

COVID-19 Vaccine Delivery Methods

Pfizer and Moderna use mRNA vaccine technology and require two doses. mRNA technology has been used for years in delivering therapeutic drugs, and this is its first application to deliver vaccines. Janssen/Johnson & Johnson is a single-dose vaccine and uses viral vector vaccine delivery studied since the 1970s. Neither the mRNA or viral vector vaccine delivery methods alter your own DNA or contain live virus that can make you ill—they simply provide instructions to your immune system to produce antibodies against the virus, giving your immune system a head start to combat the virus should you become infected. All three vaccines provide protection at listed efficacies 14 days after vaccine series completion.

COVID-19 Vaccine Efficacy

Vaccine efficacy measures the percentage of disease reduction in those vaccinated, as compared to unvaccinated populations. Typical efficacy goals are 50% or higher, with COVID-19 vaccines exceeding that level. Pfizer, Moderna and Janssen/Johnson & Johnson vaccines are 95%, 94%, and 66% effective respectively, while nearly eliminating risk of severe disease, hospitalization, and death. While Janssen/Johnson & Johnson has a lower overall efficacy rate comparatively, it is also up to 80% effective against severe strains of COVID-19 that threaten a higher rate of hospitalization and death. All three vaccines appear to be effective against new strains of the virus. In addition, fully vaccinated people are far less likely to transmit COVID-19 to others.

COVID-19 Vaccine Side Effects

The most common side effect of all three vaccines is injection site pain, followed by fatigue, then headache. Some people report fever, chills, and body aches, with most side effects clearing after a day or two. Side effects are directly related to the strength of immune response, with older populations experiencing fewer, less severe side effects than younger patients with more robust immune systems. Side effects do not mean that you are sick with the disease, only that your body is doing what the vaccines instructed and is manufacturing antibodies and building immunity to the virus.

Ongoing Research

Research continues as more and more Americans become fully vaccinated and manufacturers seek full FDA approval for all three vaccines. Researchers will be able to determine how long the COVID-19 antibodies persist and whether or not booster shots will be needed for continued protection. Science, through vaccine development and efficient vaccine delivery, makes widespread vaccination possible and edges us closer to putting the COVID-19 pandemic behind us.

The information contained in this article is not intended to be a substitute for professional medical advice, diagnosis, care, or treatment. Always consult a qualified healthcare provider with questions regarding any possible health or medical condition.

Dr. Jennifer Wild, D.O. is Medical Director for Midwestern University’s Glendale Campus COVID-19 Vaccination Center and Assistant Professor for the Physician Assistant Program at the Midwestern University College of Health Sciences in Glendale, Arizona. Working as a team, Midwestern faculty and graduate students provide healthcare services to patients of all ages and at affordable costs at the Midwestern University Clinics. Visit www.mwuclinics.com/az for more information, or call 623-537-6000 to schedule an appointment.

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