RICHMOND, Va. (WRIC) — The U.S. Food and Drug Administration says the Johnson and Johnson vaccine appeared safe and effective in trials and is now likely on its way to emergency authorization.

If approved, the company says about 20 million doses would be available by the end of March; however, some have questioned how Johnson and Johnson’s one-shot vaccine compared to Moderna and Pfizer.

Dr. Michael Stevens, associate chair of the Division of Infectious Diseases at the VCU School of Medicine, says there are key differences between the three vaccines. But, he notes there are benefits of the new one from Johnson & Johnson.

“The huge advantage to the Johnson & Johnson vaccine is that it is a single shot,” he said. “As well, the Johnson & Johnson vaccine can be kept at essentially refrigerator temperatures for months, and it’s stable.”

The Pfrizer and Moderna vaccines, which use mRNA technology, require cold storing temperatures and have to be administered shortly after they’re taken out of storage.

Dr. Stevens said the Johnson and Johnson vaccine is distributed and maintained more like a regular vaccine which could have a positive impact on vaccine rollout, especially in rural areas.

Some have also raised concerns about Johnson and Johnson’s 66% efficacy, compared to Pfizer and Moderna, which exceeded 90%.

But experts are quick to note that it may not be the best comparison: The Pfizer and Moderna clinical trials didn’t take into account new variants and still had 100% effectiveness against hospitalizations and deaths.

“We have really done ourselves a disservice with how wildly effective the Pfizer and Moderna vaccines are,” Dr. Stevens said. “No one is going to say they don’t want a highly effective vaccine. We are all grateful, but at the start of the pandemic if you said you were going to produce a 60% effective vaccine, that would have been beyond most people’s wildest dreams. Compare that to the flu [vaccine], which can be 50% to 60% effective some years.”

Overall, Dr. Stevens says, all three vaccines have been proven to be safe and effective.

“If it has emergency use authorization from the FDA, it has been held to a very high safety standard. These vaccine trials have had just massive amounts of patients,” he said.

The FDA independent advisory committee plans to meet on Friday to discuss if it will recommend Johnson and Johnson’s vaccine for emergency use. If endorsed by the FDA, the vaccine could be granted authorization as early as Friday evening.