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Key Clinical Updates in Common Viral Respiratory Infections

The new coronavirus infection, COVID-19, reached pandemic proportions in March 2020. CMDT has updated the everevolving knowledge of SARS-CoV-2 and the related disease online at accessmedicine.com.

1. SEVERE ACUTE RESPIRATORY SYNDROME—CORONAVIRUS 2019 (SARS-CoV-2)

ESSENTIALS OF DIAGNOSIS

  • Wide spectrum of symptoms.

  • Asymptomatic in at least 20–35%.

  • Upper respiratory tract illness with fever and cough most often when symptomatic.

  • The clinical triad of cough, fever, and dyspnea is infrequent (less than 15%).

  • Advanced pulmonary complications (pneumonia, acute respiratory distress syndrome [ARDS]) with fulminant disease.

  • Mortality of 1–21% (the higher for the New York City outbreak).

  • High predilection for the elderly, the immunocompromised, those with chronic diseases, those living in crowded conditions.

General Considerations

In late 2019, a novel coronavirus emerged, spreading quickly from its origin in China across the globe. The virus was initially named “novel coronavirus 2019” (2019-nCoV), accounting for the year of discovery, its status as a “novel” virus, and its family name (coronavirus, CoV). The CDC-recommended terminology for the virus is SARS-CoV-2, and the illness caused by this virus is called “Coronavirus Disease 2019” or COVID-19 (https://www.cdc.gov/coronavirus/2019-ncov/summary.html).

Coronaviruses are a large family of viruses commonly found in humans as well as many other species of animals, including bats, camels, cattle, and cats. Like MERS-CoV and SARS-CoV-1 as well as human common cold coronaviruses HC43 and HKU1, the SARS-CoV-2 virus is a betacoronavirus, which is one of the four genera of coronaviruses (only the alphacoronaviruses [coronavirus NL63 and 229E] and betacoronaviruses affect humans); all of these coronaviruses have their origins in bats. The spread of SARS-CoV-2 from bats was perhaps amplified by pangolins, an Asian anteater whose scales are traded on black markets for circulatory problems, although this latter theory remains under investigation.

COVID-19 was declared a pandemic by the WHO on March 11, 2020. SARS-CoV-2 appears to have made its transition from bats to humans in a seafood market in Wuhan, China in late 2019. The earliest known case in the United States was documented on January 21, 2020, in a man who had recently returned to the state of Washington from China. The first US case that was not associated with travel or contact with infected travelers was identified in February 2020 in Solano, California. Three cases that occurred in February and early March 2020 from Santa Clara County, California, were identified as COVID-19 by postmortem examination. As of May 22, 2020, the confirmed number of global cases is over 5.1 million, including more than 333,000 deaths. The United States reported the largest number of cases at almost 1.6 million cases (and over 95,000 deaths).

Early in the outbreak, most fatalities were from the Chinese province of Hubei and its capital, Wuhan. By early March 2020, case numbers outside of China were growing faster than inside China; particular foci of exponential growth ...

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