Two vaccine trials show promising results, but there's still a long way to go

Moderna COVID-19 vaccine trial
Posted at 6:29 PM, Nov 16, 2020
and last updated 2020-11-16 20:29:16-05

DENVER — Within a week of one another, two major pharmaceutical companies have announced positive early results from their COVID-19 vaccine trials.

Pfizer and Moderna have indicated that their vaccines have a 90% and 94.5% efficacy rate, respectively. The vaccines both use messenger RNA to help create antibodies for patients to be able to fight off the novel coronavirus.

“That, I think, is very reassuring that you have two independent experiments that have come to the same conclusion, that the conclusion is real,” said Dr. Thomas Campbell, the chief clinical research officer for UCHealth and the associate dean for clinical research at the University of Colorado School of Medicine.

The volunteers for these trials started to be enrolled on July 27. The Moderna trial was conducted in 99 sites across the country, including the University of Colorado School of Medicine. It enrolled 217 participants in the trial, who contributed to the data the pharmaceutical company used for its results.

There are some differences in the vaccines, however. First, Pfizer’s version must be stored in a freezer that can reach -70° Celsius while Moderna’s can be stored at -20° Celsius, which is the temperature of an average freezer.

Most major hospitals do have freezers that are cold enough to store both, however the temperature difference could add an advantage to the Moderna vaccine.

“It is a bigger issue for distribution and administration of the vaccine,” said Campbell.

Meanwhile, the efficacy rates for the two are slightly different but not something Campbell is overly focused on since anything 90% or higher means the vaccine is as effective as the measles, smallpox or mumps vaccines.

“We were bracing ourselves for something much lower and for this to be at 90% or greater right now, that’s very encouraging. Even if that drops over time and we understand where the gaps are, this is a very good starting point,” said Dr. Gregg Dean, the Department of Microbiology, Immunology, and Pathology at the College of Veterinary Medicine and Biomedical Sciences at Colorado State University.

Dr. Dean and Dr. Campbell are cautiously optimistic about the progress of these two vaccines but say there is still a long road ahead before they will be widely distributed.

For one thing, the clinical trials of the vaccines will continue for at least two years to get more in-depth results.

“All the data we have so far are on the short-term safety and efficacy and we still need to collect data to evaluate the long-term safety and efficacy. Sometimes there are side effects from vaccines that might not be apparent for months,” Dr. Campbell said.

The efficacy of the vaccine could also decrease overtime, meaning the patient would need a booster shot to keep their antibodies up.

The efficacies for these vaccines were also measured in very controlled circumstances, which could prove to be very different than how the vaccine works in ordinary life.

Pregnant women and those who are immunosuppressed were also not included in the trials and there is little indication at this point how they would be affected by the vaccines.

Both Moderna and Pfizer have said they plan to file for an emergency use authorization with the Food and Drug Administration (FDA) so that they will be able to distribute the vaccines to specialized groups (like frontline workers, for instance) while the clinical trials continue.

“COVID right now is pretty much raging across the country and so, as in any medical condition, we have to weigh risk versus benefits and the risk of doing nothing is tremendous,” Dr. Campbell said.

He anticipates that the general public won’t be able to gain access to the vaccines until the second quarter of 2021.

Dr. Dean has been working on a COVID-19 vaccine of his own that takes a different approach from the Moderna and Pfizer versions. His version puts a greater emphasis on the cost and global distribution capabilities. Dr. Dean’s team is trying to create a vaccine that can be stored at room temperature, is inexpensive and easy to manufacture.

“I think everybody needs to brace themselves and understand that we are going to see a number of vaccines roll out. We can’t just be dependent on one or two. These two companies are the first, they’re not going to be the last and maybe in the long run, they’re not going to be the best,” Dr. Dean said.

He has been heartened by the amount of collaboration happening around the world, saying it is unprecedented and could serve as a template for how problems can be addressed in the future.

CU also has trials going on for the Johnson and Johnson vaccine trial while another site in northern Colorado is enrolling volunteers for the Astrazeneca trial.

“It’s important that we continue to conduct those studies because we need more than one vaccine or more than one type of vaccine in order to get the coverage that we need, and then also we don’t want to put all of our eggs in one basket,” Dr. Campbell said. “We need some back up plans. So, it’s important to recognize that this is not the end. It’s just one of the first steps.”