With COVID-19 case numbers reaching nearly 80,000 and new cases popping up outside China in Asia, Europe, the Americas, and the Middle East, containment of the SARS-CoV-2 virus seems to be failing. There are many factors that make containment difficult including asymptomatic viral shedders, difficulty in screening to identify infected individuals, thousands of international travelers each day that could be spreading the disease, and at least 2 routes of transmission. The primary mode of transmission is direct contact with respiratory droplets in the air produced when an infected individual coughs, sneezes, or even talks. These droplets don’t project far (6 feet at best) and don’t hang in the air for long, so it requires fairly close and immediate contact with the infected person to contract the virus this way. Unfortunately, the virus remains viable on inanimate objects for at least 9 days under some conditions, and possibly longer. Consequently, viruses present in these infected droplets can contaminate the surrounding surfaces and remain for days. Uninfected people who touch the contaminated surfaces can pick up viruses on their hands and then transfer the viruses to their mouth, nose, or possibly eyes to initiate an infection. This second mode of transmission is difficult to prevent as continually and effectively decontaminating public areas is not possible. Because of these issues, the Centers for Disease Control & Prevention (CDC) is now warning that the spread of COVID-19 into the United States is likely, though the domestic risk for Americans is still extremely low. If you are interested in following the global spread check out the NextStrain website for a cool, interactive map of cases.
While a quick victory over SARS-CoV-2 now seems unlikely, aggressive research is providing much-needed information about the virus and its disease. Current data indicate that 80% of infections are asymptomatic to very mild, though these individuals may still shed virus and be infectious to others. Roughly 14% of confirmed cases are classified as severe with patients developing pneumonia and requiring medical care, though these patients generally survive. Only about 5% of cases become critical with more systemic reactions including respiratory failure, septic shock, and multi-organ failure leading to death in about half of the critical cases. However, severe and critical cases are almost exclusively in the elderly and individuals with underlying health issues such as cardiovascular disease, diabetes, cancer, hypertension, or chronic respiratory issues. Men have died at almost twice the rate as women, but children seem to be the least affected by this virus, likely due to differences in immune responses between children and adults. Numerous studies are underway testing various antiviral drugs and new vaccines with some promising results already being reported, so the fatality rate will undoubtedly decrease as effective therapeutics and/or preventatives become available.
It’s still possible that new disease cases will diminish with warmer springtime weather as happens with other seasonal respiratory infections, but health officials are uncertain if this will be a permanent end to the epidemic as with the original SARS outbreak. Alternatively, SARS-CoV-2 may establish itself as a new, endemic human virus that would persist indefinitely. As scary as this sounds, by comparison with the influenza virus the SARS-CoV-2 virus is still a minor league virus in terms of numbers of cases and deaths as shown in the tables below reflecting numbers as of February 26, 2020.
Influenza kills an average of 20,000-40,000 Americans every flu season yet the public hardly seems to be aware of the magnitude of deaths caused by this perennial major killer. So for now, it’s more important to be vigilant against influenza than SARS-CoV-2. I’ll have more updates as new developments arise.