What 'Side-effect' actually Happened to Participant in 'Oxford's Astrazeneca' Vaccine Trial?

Earlier this week, the clinical human trials of the vaccine developed by the Oxford University and AstraZeneca were paused in several countries. The reason behind this sudden pause was identified to be an adverse side-effect that the vaccine gave a woman.
The woman is said to have developed a severe neurological symptom, said a spokesperson for AstraZeneca on Thursday. The participant is expected to have developed transverse myelitis, which is a rare case of inflammation of the spinal cord said Matthew Kent, spokesman.
“We don’t know if it is (transverse myelitis). More tests are being done now as part of the follow-up,” said Kent. He further added that a “standard review process triggered a pause to vaccination to allow review of safety data.” AstraZeneca pointed out that this side-effect could be a coincidence and that such temporary pauses in medical researchers are not unusual. Investigating such unexpected reactions are important, said the spokesperson.
AstraZeneca began recruiting over 30,000 volunteers in the US for testing the vaccine in August. Further, thousands of people from Britain, South Africa, and Brazil were also included in the study. While the study is paused in several countries over this safety concern, the World Health Organisation has said that it is not overly concerned about it and that this is a “wake-up call” to the world about the realities of medical research.