MADISON, Wis. (SPECTRUM NEWS) -- As the investigation continues into AstraZeneca’s new COVID-19 Phase 3 Trial, more top doctors say they are proud of the drug manufacturer after the medical company voluntarily put the trial on pause.

"What this tells me is that even at significant financial penalty, at significant reputational injury, that they are going to put safety first," UW Health Chief Quality and Safety Officer Dr. Jeff Pothof said. 

Dr. Pothof last week made history as the first U.S. COVID-19 vaccine trial participant. He says after the injection, he felt some tenderness as well as a few other side effects.

"For the rest of the day, I actually felt really great, I did wake up at about 3 o'clock the next morning with some just real mild chills," he said. "I took my temperature to see about a fever and I didn't. The next day, I had a mild headache but you know really mild took some Ibuprofen, things were good," he added.

The AstraZeneca vaccine trial now halted twice in just two months. AstraZeneca representatives say in the first instance, a patient experienced neurological symptoms, but later learned the adverse reaction was related to an undiagnosed and unrelated case of Multiple Sclerosis. The latest pause comes after an overseas participant suffered a rare but serious spinal inflammation. 

"So the reaction is obviously is a concern," Dr. Soren Christiansen, the former head of vaccines at Merck for 30 years and current CEO of Sharps Technology, knows this new development is unsettling. 

"It gets really problematic when you look at it from an individual person or family's perspective," Dr. Christiansen said. "So you can you can talk about public health and the positive impact as much as you want, but if you have someone close to you, and that person or individual has been suffering from a potential adverse event, then they don't care a lot about public health, they care about their family and their kids or whatever it is," he added.

The vaccine expert says it’s more likely the spinal inflammation was caused by something unknown and pre-existing.

"And sometimes, there's some underlying conditions that that individual was not aware of and definitely the physician that included the patient in the study was not aware of," he said.

Dr. Christiansen says many more trials halts could come after this one. 

"No, I would not fall out of my chair if that should happen. I mean, that's the good thing about science, that you have a hypothesis and you trying to prove, and then sometimes it proves right and sometimes it proves wrong," he said.

As the Phase 3 Trial halt continues, the nine top COVID-19 vaccine manufacturers announced a pledge to ensure safety remains paramount throughout the process. Presently, both physicians believe a safe and effective COVID-19 vaccine is still well on the way.

"I’m convinced we will have vaccines against COVID-19 and we will have more than one," Dr. Christiansen said.