This is a fascinating little paper in the medical journal Nature Medicine. It is written by an Australian group arguably the top leaders in the field of antiviral immune responses.
It describes a 47-year-old woman from Wuhan, Hubei province, China. She presented to an emergency department in Melbourne, Australia. Her symptoms commenced 4d earlier with lethargy, sore throat, dry cough, pleuritic chest pain, mild dyspnea and fevers. She had traveled from Wuhan to Australia 11 days earlier. She had no known contacts with COVID-19 cases and was otherwise healthy.
She had a fever of 38.5 °C, and pneumonia by clinical exam and chest XR. PCR tests for SARS-CoV-2 were first positive at 4d (4 d after symptoms onset). But PCR tests were no longer positiive after d7. She recovered and was discharged on d11.
There follows a detailed description of her immune response. It involved all components of the immune system known to partake in responses to other viruses like the flu.
Why is this important?
- It defines a normal immune response leading to disease resolution
- it will be compared with the immune response of patients that don’t do well or succumb to COVID-19. This will lead to insights about why they do poorly.
- antibodies and various types of T cells all seem to be important
- unlike H7N9 influenza disease, where inflammatory cytokines are elevated, minimal pro-inflammatory cytokines and chemokines were found in this patient
- robust and broad immune responses can be elicited to the newly emerged virus SARS-CoV-2, similar to the avian H7N9 disease and suggest that early immune responses might correlate with better clinical outcomes.
- NB in this patient testing by PCR was negative after D7 (many patients are not tested that early and results would therefore be falsely negative)
- I think patients doing poorly on ventilators in the ICU, should get trials of plasma from recovered patients as this would provide antibodies. This is an old type of therapy first used for Spanish Flu patients with some success. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4781783/