By Kathleen Berger, Executive Director for Science & Technology
The remarkable success of first generation COVID-19 vaccines is encouraging to the scientific community. COVID-19 vaccine trials accelerated towards approval for emergency use authorization at an unprecedented speed. In November, pharmaceutical companies Moderna and Pfizer reported their mRNA vaccines are 95% effective in clinical trials. Both Moderna and the Pfizer-BioNTech COVID-19 vaccines are approved for emergency use.
The Saint Louis University Center for Vaccine Development is participating in the phase 3 trial for Moderna’s mRNA vaccine. The center’s clinical director, Sharon Frey, MD, is principal investigator.
“That type of effectiveness we don’t see in vaccines. That’s a very high rate. However, that is based on very preliminary data and we really won’t know the true answers until later on in the study,” said Frey. “People should be very excited that at least two vaccines so far, both the Pfizer and the Moderna vaccines, look like they are going to be effective.”
Rachel Presti, MD, PhD, is leading the COVID-19 vaccine effort for Washington University School of Medicine in St. Louis. Presti is the medical director of the Infectious Diseases Clinical Research Unit on the Washington University Medical Campus, and she’s the principal investigator for Johnson & Johnson’s Janssen COVID-19 vaccine clinical trial.
Johnson & Johnson’s COVID-19 vaccine clinical trial is also taking place at the Saint Louis University Center for Vaccine Development with Dr. Sharon Frey as principal investigator.
Participants receive this Janssen COVID-19 vaccine candidate or a placebo, a shot of saline that does nothing. Johnson & Johnson’s Janssen vaccine is one the emerging adenoviral vector–based vaccine candidates.
“The adenovirus 26 (adenovirus serotype 26, Ad26) is a sort of rare version of adenovirus. It’s a human adenovirus, common cold kind of virus,” said Presti. “It’s been mutated so it doesn’t replicate. It doesn’t cause the cold anymore, but now expresses the spike protein from SARS-CoV-2, so that you can get an immune response to it.”
The successful Pfizer-BioNTech and Moderna mRNA vaccines are a new technology. Before the pandemic, mRNA vaccines have a history of strong immunity against infectious diseases in animal models. The vaccines are not made up of the actual pathogen, meaning that they don’t contain weakened, dead, or noninfectious parts of a virus. Instead, they contain genetic information about the pathogen. MRNA vaccines are safe so far in clinical trials that will continue for about two years. Side effects are mild to moderate lasting 2 to 3 days.
“We see injection site discomfort, just like you would with any vaccine, maybe some soreness or tenderness. We see people complain of headache, muscle ache, maybe joint aches, maybe a little bit of fever,” Frey said. “If you are having side effects to a vaccine, you are certainly reacting to it and that is a good thing in the sense that your immune system is recognizing the vaccine, which we want it to, and we want it to make a strong immune response against the vaccine.”
Presti said there is a greater confidence with the Janssen vaccine trial in regards to proving safety. She explained there is a similar adenovirus vaccine that already has a proven safety record for the prevention of Ebola.
“We have safety data in a similar kind of vaccine, not the same vaccine, but in a similar vaccine in hundreds of thousands of people. And we just don’t have as much safety data in mRNA,” said Presti.
Before Johnson & Johnson’s large-scale clinical trial, smaller Janssen COVID-19 vaccine studies indicate only one shot would be needed, as opposed to receiving two shots about a month apart for mRNA vaccines.
“They were able to see the antibody response was good even with just one dose,” said Presti.
The next big challenge is physically getting the COVID-19 vaccine to everyone. Presti said the Janssen vaccine would be a huge bonus because it would only require refrigeration, not freezers.
“It would be easier, I think, if Janssen worked as well as Moderna and Pfizer. It might be easier to give that vaccine because you don’t need cold storage and you only need a single dose.”