The National Institutes of Health (NIH) in the US evaluated samples taken from autopsy carried out between April 2020 and March 2021. In 11 of the patients, they thoroughly sampled the neurological system, including the brain. The study was published in Nature.

The median age was 62.5 years, and 30% of the patients were female. Three or more comorbidities were present in 27 individuals (61.4%). The median number of days between the onset of symptoms and mortality was 18.5. Virus replication was seen during the first two weeks after the onset of symptoms in a number of non-respiratory sites, as per the authors.

In addition, the researchers were able to isolate live SARS-CoV-2 virus from a variety of organs both inside and outside the respiratory system, such as the adrenal gland, eye, brain, heart, lymph nodes, and digestive tract. 25 out of the 55 tested specimens (45%) had the virus isolated.

According to the analysis, SARS-CoV-2 largely infected and harmed lung and airway tissue. In addition, the researchers discovered viral RNA in 84 different body fluids and sites, and in one instance they identified viral RNA 230 days after a patient's symptoms started.

In the hypothalamus and cerebellum of one patient, the spinal cord, and the basal ganglia of two more patients, the researchers found SARS-CoV-2 RNA and protein. However, they discovered minimal harm to brain tissue "despite significant viral burden".