Around Christmas 2015 (post-vaccination day 6), while on leave, patient began experiencing the sensation of his feet being cold; he wore socks and slippers to try to keep them warm. Later, the sensation transitioned to a feeling of numbness and tingling in his toes and feet, which gradually progressed up his legs to his knees and then medial thighs. This was followed by numbness and tingling in his fingers and hands, which gradually progressed to his elbows and then biceps. Right after the first of the year, patient traveled for a day. He noted his legs felt weak and he was having problems walking and problems with his balance; he tripped when trying to step up on a curb; he held on to his friend while walking due to his "unsteadiness". Around this time, patient also felt like his hand strength was decreased, as he was having difficulty writing. On 5 Jan 2016, post-vaccination day (PVD) 20, after returning to training, patient sought evaluation at his medical clinic. His physical exam was normal except for absent deep tendon reflexes (DTR) in all extremities. A brain MRI and multiple lab tests were ordered (Refer to Diagnostics section below for results). Follow-up was planned for the following morning. On 6 Jan 2016 (PVD21), patient returned to the clinic and reported no change in his symptoms. There were no changes in his physical exam. Patient was referred to Neurology at Medical Center. On 7 Jan 2016, patient was evaluated by Neurology. Patient reported history as above. He denied problems swallowing, breathing, visual changes, and bowel or bladder problems. He denied recent out of country travel and denied any recent illnesses or infections. On exam, decreased responses to pain and temperature in stocking/glove distribution was noted, with minimal decrease in vibratory sense in his lower extremities also noted. Trace decrease in strength (4+/5) was noted in bilateral wrist extensors and with left digital flexion. There was no pronator drift. There were no involuntary movements noted. His gait and stance were normal. Bilateral ankle and knee DTRs were absent. Brachioradial DTRs were 2+ and triceps and biceps DTRs were 1+. Per Dr.'s Assessment: Polyneuropathy, unspecified: presentation of ascending paresthesia symmetrically over weeks with minimal weakness, mild sensory loss and length dependent DTR loss on exam raises the question of acute inflammatory demyelinating polyneuropathy (AIDP). Appropriate labs negative for reversible metabolic, nutritional, infectious causes of neuropathy. No apparent toxic exposure. If due to AIDP/inflammatory neuropathy, progression has been slow with mainly sensory symptoms, subtle findings on exam, and at this point walk/swallow/use of hands/breathing is not threatened. In fact, risk of treatment with IVIG is about the same as risk of underlying condition...While progression of symptoms has been slow/slight, there could be an acceleration, and he should go to ER immediately should he notice problems with breathing, swallow, or balance...His symptoms may progress or plateau/improve, as long as symptoms do not affect function significantly where treatment is a consideration, there is no value to EMG or spinal tap. If symptoms progress or persist, then will need to reconsider. Patient returned to work, but continued daily medical follow-up. He was able to complete his training. By the end of Jan 2016, patient's symptoms were completely resolved and he felt like he was "back to normal".