Since December 2020, the U.S. Food and Drug Administration (FDA) has granted emergency use authorization (EUA) to three COVID-19 vaccines: the Pfizer vaccine (BNT-162b2), the Moderna vaccine (mRNA-1273), and the Johnson & Johnson vaccine (Ad26.CoV2.S). Use of the latter was temporarily paused by the CDC for approximately two weeks, but the pause was lifted on April 23, 2021.

At least six other vaccines are currently available outside the U.S. Learn more about the different COVID-19 vaccines.*

About the vaccines

In addition to effectiveness and safety, factors that influence COVID-19 vaccine production and distribution have included:

• Vaccine technology (how it provides immunity)
• Storage requirements 
• Dosage manner and number
• Amount needed to serve the population size
• Speed of development
• Rollout logistics 

Vaccine characteristics

Several immunization mechanisms (e.g. DNA, RNA, viral vector, protein subunit) can be used for vaccine development, and the mechanism or form of technology used in a particular vaccine will affect the dosage and storage requirements, as well as the possible side effects.

Of the three vaccines currently available for use in the United States, the Pfizer and Moderna vaccines both make use of a fairly new technology called messenger RNA (mRNA) and require two doses, two weeks apart. Messenger RNA is the genetic material that can be programmed to instruct our bodies to create a harmless protein that nevertheless triggers an appropriate immune response. It does not affect our DNA. 

The Johnson & Johnson vaccine requires only one dose and uses a traditional viral vector approach similar to the one used for flu and smallpox vaccines. This approach involves placing a weakened or inactive germ into our bodies to trigger the immune response. 

While the vaccines won’t prevent people from getting COVID-19, the research shows that they are effective at preventing severe illness, hospitalization, and death from the virus.

Vaccine rollout thus far

As of August 02, 2021, providers in the U.S. have administered over 346,924,345 shots according to the Centers for Disease Control and Prevention (CDC). Their COVID Data Tracker also shows that approximately 164,919,670 people have been fully vaccinated. Although the average number of new daily confirmed cases has spiked considerably, these spikes are occurring primarily in areas with low vaccination rates. 

As of July 27, 2021, the CDC also stated that Americans who are fully vaccinated against COVID-19 may safely resume activities that you did prior to the pandemic.

To reduce the risk of being infected with the Delta variant and possibly spreading it to others, the agency also recommends that you wear a mask indoors in public if you are in an area of substantial or high transmission.

While federal health officials are being cautiously optimistic about vaccinated individuals reconnecting socially, they have issued repeated warnings about lifting restrictions too soon and possibly setting off a fourth wave of infections. The guidance is a “first step,” Dr. Rochelle Walensky, director of the CDC, said at a White House news conference. “It is not our final destination.”

For the most up-to-date vaccine and new COVID-19 case numbers, please refer to the CDC’s COVID Data Tracker.

*Cennimo, D. J. (2021, Mar. 4). COVID-19 Vaccines. Medscape.  https://emedicine.medscape.com/article/2500139-overview 

Much about the novel coronavirus, i.e., COVID-19, is still not fully understood. As research progresses and our knowledge of the virus increases, information can change rapidly. We strive to update all of our articles as quickly as possible, but there may occasionally be some lag between scientific developments and our revisions.