COVID-19 vaccine safety information

Updated April 4, 2021

Vaccine development usually takes years. However, in this case, scientists had already begun researching coronavirus vaccines during previous outbreaks like Severe Acute Respiratory Syndrome (SARS) in 2003, and Middle East Respiratory Syndrome (MERS) in 2012. SARS, MERS and COVID-19 are all members of the coronavirus family. Lessons learned from this earlier research provided a head start, allowing for rapid development of a COVID-19 vaccine. 

The U.S. Food and Drug Administration (FDA) authorized Pfizer's COVID-19 vaccine for emergency use on Friday, Dec. 11, Moderna’s on Friday, Dec. 18, and Johnson & Johnson’s on Saturday, Feb. 27.

Emergency use authorization

During an emergency, the FDA can issue an emergency use authorization (EUA) to provide more timely access to critical medical products like medicines and tests. 

The EUA process allows the FDA to authorize use based on less data than would be required for full approval, clearance or licensing. 

Once the EUA is given, it is in effect until the emergency ends, but it can always be revised or revoked as the emergency evolves, or more data becomes available. 

Vaccine ingredients 

Ingredients will vary by vaccine type. As the FDA approves the vaccines, better answers will become available. The vaccine manufacturers are required to submit this information as part of the approval process.

View a list of ingredients for the Pfizer vaccine here

View a list of ingredients for the Moderna vaccine here 

View a list of ingredients for the Johnson & Johnson vaccine here 

The vaccines do NOT include: 

  • Fetal cells
  • Blood products, like red blood cells, white blood cells, plasma or platelets
  • COVID-19 virus cells
  • Microchips
    • Sometimes there are microchips on the outside of a syringe, so the health care professional can scan it quickly for digital records. The world’s tiniest microchip is still much too big to insert into an immunization shot. 

mRNA technology 

Some of the COVID-19 vaccines, including the Pfizer and Moderna vaccines, use mRNA, or messenger RNA, to instruct your body to build the coronavirus’ spike protein. Once your body makes the spike protein, your immune system then produces antibodies to combat the coronavirus when it encounters it later. Learn more about mRNA vaccines.  

Adenovirus vector technology

The Johnson & Johnson vaccine is an adenovirus vector vaccine. (Adenovirus is the virus that causes the common cold. The virus in this vaccine has been changed so that it does NOT cause illness.) With this type of vaccine, a carrier, in this case adenovirus, acts as a delivery vehicle. The adenovirus has had the coronavirus spike protein added to its DNA. The adenovirus carries that genetic material into your body, delivering its modified DNA to your cells. Your cells will then make the spike protein, activating your immune system. Once activated, your immune system creates antibodies to fight off the spike protein. Learn more about the Johnson & Johnson vaccine

If you are pregnant or breastfeeding 

There were no pregnant women included in the initial COVID-19 vaccine clinical trials.  

The FDA’s EUA states: “Available data on Pfizer-BioNTech COVID-19 vaccine administered to pregnant women are insufficient to inform vaccine-associated risks in pregnancy.”  

The American College of Obstetrics & Gynecologists Practice Advisory states: “Pregnant and lactating women who otherwise fit the criteria for inclusion in high-priority population can be vaccinated alongside their non-pregnant peers based on shared clinical decision making with the patient and her clinician.” 

The Society for Maternal-Fetal Medicine: “Strongly recommends that pregnant and lactating people have access to COVID-19 vaccines and that they engage in a discussion about potential benefits and unknown risks together with their health care providers regarding receipt of the vaccine.”  

In the data submitted to the FDA from Pfizer’s COVID-19 vaccine clinical trial, eight women became pregnant during the trial, so they were removed. Eventually, 23 people became pregnant after receiving both doses of the vaccines. Pfizer reported one poor pregnancy outcome, but that person was in the placebo group, so they did not actually receive the vaccine.  

We have no reason to believe any of the COVID-19 vaccines would harm a developing fetus or a nursing infant. What we do know: Data suggests that a pregnant woman who develops a COVID-19 infection is likely to become sicker than a non-pregnant woman who develops a COVID-19 infection.  

We encourage women who are pregnant or breastfeeding to discuss the benefits and risks of receiving a COVID-19 vaccination with their doctor.  

Officials recommend that breastfeeding women get the vaccine. We have no reason to think the COVID-19 vaccines will cause problems with lactation or breastmilk.   

If you are immunocompromised 

We recommend immunocompromised people get the vaccine.  

If you have concerns, or a specific question related to your personal condition, we encourage you to speak with your doctor before getting the vaccine.   


The Pfizer vaccine is approved for people who are 16 years of age and older. The Moderna and Johnson & Johnson vaccines are approved for people who are 18 years of age and older.

Clinical trials are just beginning to include children, so the vaccines have not been fully studied in children yet. Sometime next year we will have the results of those clinical trials.  

Blood clots

Recently, an individual in their late 40s experienced a significant medical event involving blood clots two weeks after receiving the Johnson & Johnson COVID-19 vaccine. They received treatment at Nebraska Medical Center. The incident has been entered into VAERS, the Vaccine Adverse Event Reporting System, the national vaccine safety surveillance program run by the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA). The Nebraska Department of Health and Human Services is working closely with the CDC and the FDA to review this incident.  

During the Johnson & Johnson COVID-19 vaccine phase 3 clinical trials, 14 of 40,000 participants who received the vaccine developed embolic or thrombotic (blood clotting) events. Among those who received the placebo, 10 people developed embolic or thrombotic events. Given the similarity in the amount of events between those who received the vaccine and those who received a placebo, the FDA authorized the vaccine for emergency use in the U.S.  

Over 31,700 Johnson & Johnson vaccines have been administered in Nebraska, and 4.5 million nationwide, as of April 9, 2021. All three COVID-19 vaccines remain our best chance at protecting ourselves and those we love. 

We are not currently accepting COVID-19 vaccination appointments.

Call for more information.