Naseer, who has been hired by the NIH to supervise the vaccine administration, said that she opted for the "challenging and risky job" as she knew the work requires interaction with a lot of volunteers and she would risk catching the virus and passing it on to her children.

But being a doctor, she said she knew how to protect herself "by following the protective measures."

It was also a new experience for Naseer in a phase III trial of a vaccine.

"I have studied phase III trials in books like all of the other doctors in Pakistan, because the country doesn't have enough resources and research to conduct the trials. So it is a great opportunity for Pakistan to conduct such trials here," she said, adding: "It helped us to be in the countries working on vaccine development and further strengthened Pak-China friendship."

Naseer said that Chinese experts provided them with all technical support and the knowhow about the trials, enabling the trials to be conducted efficiently. About 95 percent of the trials have already been completed, she added.

Trial sample will be sent to a third-party observer which will give its final evaluation of the vaccine, she said.