How do the COVID-19 vaccines differ?

On Thursday, February 25^th, the Food and Drug Administration is expected to vote on whether to issue an emergency use authorization to Johnson & Johnson’s (J&J) new single-dose COVID-19 vaccine candidate. If approved, it will join the Pfizer-BioNTech and Moderna vaccines in the ongoing rollout across the United States. 

As part of the “COVID-19 Vaccines: Asked & Answered” video series in which Penn State faculty experts help educate the community on the latest information related to the COVID-19 vaccine, Suresh Kuchipudi, clinical professor of veterinary and biomedical sciences, explains that, like the Pfizer and Moderna vaccines, the J&J vaccine is backed by years of research and has been shown through rigorous clinical trials to be safe and effective.  

“COVID-19 vaccines instruct our bodies to make antibodies against the Spike protein of the virus so when we are subsequently exposed to the virus, these antibodies protect us from being infected,” said Kuchipudi.

However, he explained, the J&J vaccine works differently from the Pfizer-BioNTech and Moderna vaccines in that it delivers instructions for making the Spike protein in the form of DNA encased in a harmless adenovirus vector. Some other vaccines, including the one developed by the University of Oxford and AstraZeneca, are also based on adenoviruses. 

By contrast, the Pfizer and Moderna vaccines use messenger RNA (mRNA) technology, which delivers the message to make the Spike protein in the form of single-stranded mRNA (as opposed to double-stranded DNA) encased in lipid nanoparticles.

Kuchipudi noted that while there are technical differences among these vaccines, it is important to recognize that all the vaccines will have gone through a very rigorous process before the FDA authorizes their use.  

As additional information regarding vaccine distribution becomes available, the University will share updates on Penn State News and Penn State’s Virus Information website. Individuals also can call the COVID-19 Response Center at 814-865-2121 for specific questions. For those who have a question about the COVID-19 vaccines, call the PA Health Hotline at 1-877-724-3258.