a diagnosis of GBS. Of significance to Dr. Quintero was the diminished sensory response appearing only on plaintiff’s left arm and leg, whereas the symptoms of GBS are typically symmetrical. Plaintiff finally had a spinal tap in November of 1978 under the supervision of Dr. Quintero. The test revealed an elevated gamma globulin level which is symptomatic of multiple sclerosis. Another test, a visual evoked response performed at Dr. Quintero’s request, revealed abnormalities suggesting multiple sclerosis.
Plaintiff engaged in a final battery of tests conducted by Barry B. Blum, Ph.D. Dr. Blum’s report maintains that plaintiff does not suffer from any psychiatric disorder. Dr. Blum wrote that he was “unable to determine the specific cause of [plaintiff’s] problems, nor [was he] able to relate them to the Swine Flu vaccination.”
In addition to plaintiff and several other lay witnesses, five physicians testified at trial. Dr. Peter Quintero testified that plaintiff suffered from Guillain-Barre Syndrome caused by the swine flu vaccine. Dr. Quintero acknowledged that plaintiff’s GBS was atypical due to the asymmetrical (left-sided) numbness and the lack of any motor abnormalities.
Charles M. Poser, M.D., Professor and Chairman of Neurology at the University of Vermont College of Medicine, testified that plaintiff also experienced a rare form of GBS with almost purely sensory manifestations as a result of the vaccine. Dr. Poser also observed that some time after the vaccination, plaintiff suffered a minor stroke involving the right upper brain which resulted in the persistent numbness of the left side (excluding the tongue) and plaintiff’s visual abnormalities.
Martin G. Lewis, M.D., Professor and Chairman of the Department of Immunopa-thology from Georgetown Medical Center in Washington, D.C., conducted blood serum tests on a sample provided by plaintiff. The results indicated that plaintiff came within the class of persons who has had GBS and received the swine flu vaccine. Dr. Lewis was unable to state whether plaintiff’s condition was causally related to the vaccine.
Dr. Stanley Sontag, a general practitioner, testified that plaintiff had a neurological reaction as a result of the swine flu vaccination. Dr. Sontag, however, was not able to indicate what specific type of neurological disorder plaintiff suffered.
Dr. James Austin, Professor and Chairman of the Department of Neurology at the University of Colorado Medical Center testified that plaintiff did not suffer from GBS based on the criteria established by the National Institute of Neurological Communicable Diseases and Stroke. Dr. Austin was unable to determine the nature of plaintiff’s disorder. Dr. Austin did, however, testify to a reasonable degree of medical certainty that plaintiff did not suffer any neurological disorder as a result of the swine flu vaccination.
The district court found that plaintiff did not contract GBS because none of the symptoms classically associated with GBS were present in plaintiff. Secondly, the court found that plaintiff had not established causation between the injection of swine flu vaccine and the alleged injury.
Under the Federal Tort Claims Act, 28 U.S.C. §§ 1346(b), 2674, as made applicable by the remedial provisions of the Swine Flu Act, 42 U.S.C. § 247b(k)(2)(A), the law of the place where the act or omission occurred determines the legal basis for liability. In this case, the injection was administered in Colorado. The district court noted that under the applicable Colorado law, an event is the proximate cause of an injury if, in the natural and probable sequence of things, it produced the claimed injury. Reaves v. Horton, 33 Colo.App. 186, 518 P.2d 1380, 1385 (1973), rev’d on other grounds, 186 Colo. 149, 526 P.2d 304 (1974). The burden is upon the plaintiff to prove by a preponderance of the evidence that the vaccination was the proximate cause of her neurological problem. Martin K. Eby Const. Co. v. Neely, 344 F.2d 482, 485 (10th Cir.1965), aff’d, 386 U.S. 317, 87 S.Ct. 1072, 18 L.Ed.2d 75 (1967). The district court ruled that plaintiff did not meet this bur