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Covid-19: Lessons from first US case of community transmission
Following the diagnosis, the US ramped up testing to discover the staggering magnitude of the coronavirus pandemic. It now has the highest number of cases in the world, with at least 190,000 infections and over 4,000 deaths.
While health ministry officials insist that increasing clusters of coronavirus disease (Covid-19) cases across India should be classified as “local transmission” -- where the infection source can be traced -- rather than “community transmission” -- where the source cannot be traced for a large number of people -- clinicians in California have published a detailed case study of the first case of community transmission in the United States on February 26, underlining the need for expanded, aggressive testing.
Following the diagnosis, the US ramped up testing to discover the staggering magnitude of the pandemic. It now has the highest number of cases in the world, with at least 190,000 infections and over 4,000 deaths. The study was published on March 31.
The case made the US “ramp up testing”. The woman tested positive on February 26 and the US Food and Drug Administration (FDA) issued a policy on expediting testing on February 29.
For clinicians, the medical history of an otherwise healthy woman in her 40s, whose chest infection rapidly deteriorated to near-fatal septic shock, offers critical clues to the management and treatment of Covid-19.
The woman was admitted to the UC Davis Medical Center in Sacramento, California, with a respiratory infection, which chest imaging indicated was community-acquired pneumonia (CAP).
Her condition worsened within 24 hours, and she was quickly moved to the intensive care unit (ICU) and put on ventilator support to help her breathe. She was given antibiotics, including linezolid, piperacillin-tazobactam and azithromycin, to kill a possible bacterial infection.
The battery of tests over the next few days included a viral panel, respiratory culture, blood cultures, bronchoscopy cultures to identify infection source, but all came up negative.
The doctors then started suspecting Covid-19 but did not test her as she had no history of international travel or contact with a person with the coronavirus disease -- in line with the testing criterion of the US Centers of Disease Control at the time.
She next developed acute respiratory distress, with fluid building up in her lungs and making it difficult for her to breathe, which quickly worsened to septic shock, a potentially fatal sudden drop in blood pressure in reaction to severe infection.
The severity of her respiratory condition and her lack of response to all supportive treatment led the clinicians to put her on airborne precautions and strict contact precautions and finally get her tested for Covid-19. Two days later, the results came back positive.
Since there were no approved antiviral therapies for Covid-19, the UC Davis got regulatory approval to treat her with an investigational drug called remdesivir, the broad-spectrum antiviral developed by Gilead Sciences that has shown promise against coronaviruses in animals.
Remdesivir infusions resulted in the patient needing significantly less ventilator support and having better blood oxygen levels and chest X-ray results. Fourteen days after first admission to UC Davis, she was taken off ventilation. She has since been discharged and is recovering at home.
“Remdesivir is an experimental drug, though there are ongoing clinical trials to analyse its safety and effectiveness against Sars-Cov2, the virus that causes Covid-19. In Medanta, we managed the 14 Italian patients symptomatically and all but one have recovered and been discharged. Only one is still in the ICU, but she is stable,” said Dr Yatin Mehta, chairman, Chairman Institute of Critical Care and Anaesthesiology, Medanta-The Medicity, Gurugram, where India’s first large group of 14 tourists was isolated for treatment in March.
The US case study emphasises knowledge gaps in the diagnosis and management of Covid-19 patients in the absence of known community transmission. Without clear risk factors, such as travel history, contact, co-morbidities like hypertension and diabetes, and advanced age, Covid-19 infection can initially masquerade as pneumonia.
“According to recent guidelines in India, all hospitalised patients with severe acute respiratory infection, such as acute respiratory distress syndrome or pneumonia without an explanatory diagnosis, must be tested for Covid-19 even if no clear source of exposure is identified,” Dr Mehta.
The US study underscores the value of expanded testing. “There are individuals in the community who are not manifesting severe enough symptoms to check with their health care providers To tackle the pandemic, there needs to be significantly faster, less expensive and more widespread testing of all patients who potentially have Covid-19,” said Michael Schivo, co-director of UC Davis Comprehensive COPD Clinic and senior author on the study, in a statement.
