LONDON - Covid-19 spreads through the whole body, and infects organs including the kidneys, heart, eye and brain, a study based on autopsies of victims has shown.

While Covid-19 is a respiratory infection, it also affects organs throughout the body, the study published in Nature shows.

Remnants of the virus were found in one patient’s brain 230 days after the patient first showed symptoms.

The results show that the virus behind Covid-19 can cause ‘systemic’ infections which linger for ‘months’, ScienceAlert reported.

The findings by America’s National Institutes of Health could offer insight into how long Covid spreads, the researchers believe.

Scientists from the National Institutes of Health (NIH) tested samples from 44 autopsies that were performed from April 2020 to March 2021 – all in patients who died with Covid-19.

None of the patients were vaccinated.

Analysis showed that SARS-CoV-2 – the virus which causes Covid-19 – primarily infected and damaged airway and lung tissue.

The researchers also found viral RNA in 84 distinct body locations and bodily fluids.

The researchers detected SARS-CoV-2 RNA and protein in the hypothalamus and cerebellum within the brain of one patient and in the spinal cord and basal ganglia of two other patients.

The researchers say they found little damage to brain tissue, "despite substantial viral burden".

The investigators also isolated viable SARS-CoV-2 virus from diverse tissues in and outside the respiratory tract, including the brain, heart, lymph nodes, gastrointestinal tract, adrenal gland and eye.

The authors wrote: "We demonstrated virus replication in multiple non-respiratory sites during the first two weeks following symptom onset."

They wrote, "Our focus on short post-mortem intervals, a comprehensive standardised approach to tissue collection, dissecting the brain before fixation, preserving tissue in RNA later, and flash freezing of fresh tissue allowed us to detect and quantify SARS-CoV-2 RNA levels with high sensitivity … as well as isolate virus in cell culture from multiple non-respiratory tissues including the brain, which are notable differences compared to other studies."

The researchers write, "Our data indicate that in some patients SARS-CoV-2 can cause systemic infection and persist in the body for month.”