You may have heard that there is a virus going around. There’s also been a lot of information, misinformation, disinformation and rumor surrounding it as well.
Here’s a test to see what you know, and what experts know or strongly suspect about SARS CoV-2, the virus that causes the disease known as COVID 19.
1. What is the origin of the name SARS CoV-2?
2. What is the current expert thinking about its origin?
3. Who is contagious?
4. How is the virus spread?
5. How widespread is it?
6. What percentage of people acquire the virus, but develop no symptoms?
7. What is the difference between someone who is asymptomatic and pre-symptomatic?
8. Are there medications that are helpful in its treatment?
OK, put your pencils down. Here are some of the answers and best expert opinion.
1. SARS CoV-2 is a Coronavirus, an RNA virus found in multiple species of mammals and birds. It is the 3rd Coronavirus to cause worldwide (pandemic) infection in humans. SARS was the 1st pandemic Coronavirus, arising in 2002 and originating in China. MERS was the 2nd pandemic Coronavirus, originating in the Arabian penninsula in 2012.
SARS CoV-2 is the 3rd and current pandemic Coronavirus. It was first recognized in Wuhan, China, late in 2019 when a cluster of patients there developed severe pneumonia. SARS CoV-2 is so named because of its close resemblance, genetically, to the first pandemic Coronavirus. The name is an acronym from Severe Acute Respiratory Syndrome CoronaVirus-2.
2. Coronaviruses, as noted, are found in multiple mammalian species. Bats are a natural reservoir, but it is felt that human exposure and consumption of an exotic animal called a pangolin resulted in its introduction in humans.
There is no credible evidence that the virus was a biologic weapon that escaped from a research laboratory, accidentally or intentionally.
3. Anyone harboring viable viral organisms can potentially transmit the disease. I use the word viable rather than live because there is debate as to whether viruses are actually living entities. Viruses do not live independent of a host, cannot reproduce without infecting a host cell of another organism and hijacking the cell’s apparatus to enable the virus to reproduce. Outside of a host, Coronavirus disintegrates at variable rates depending on where it is located.
Coronavirus has been identified on impermeable surfaces such as stainless steel and plastic, for as long as 4 days after inoculation. The virus does not remain intact as long a time on impermeable surfaces such as cardboard. Outside of a host, the virus rapidly decays in a matter of 48 to 72 hours, on average.
With regard to when the peak of infectivity occurs, the following is known. In patients who acquire the virus, shedding of the virus starts about 2-3 days before symptoms start. The viral load in the upper respiratory tract (nose, throat and upper airway) peaks around the time that symptoms begin and is high during the first week of symptoms.
Modeling studies done in China and Singapore indicated that about 50-60 percent of disease transmission occurred during the time before symptoms began.
The other factor that needs to be accounted for is that there are individuals who acquire the virus, but develop no symptoms or very mild symptoms. The absence of symptoms does not mean, however, that they cannot spread the virus. (More on that below)
4. Although, in theory, viruses can be acquired through touching contaminated surfaces, the most common mode of transmission is through droplets that are coughed, talked or sneezed into the air.
Large droplets are felt to have a range of about 6 feet; smaller droplets, which are lighter in weight, can potentially have a longer range by being suspended in the air and transmitted though air currents. Large droplet transmission is felt to be the most common mode of transmission of Coronavirus.
Talking loudly and singing are felt to be more effective modes of transmission than quiet talking (hence, some episodes of transmission in church gatherings with choirs). Duration of exposure is also important.
A very brief encounter with someone, particularly outdoors is less likely to result in transmission than a 15 minute or longer exposure to someone in an indoor environment, especially with less than 6 feet of spacing.
5. The exact incidence of SARS CoV-2 infection is not known due to inadequate testing capacity. The current numbers of cases cited are almost certainly an underestimate of infected individuals.
Also, because of asymptomatic individuals who are not tested, and untested individuals who have died, the true numerator and denominator are not known and so the true mortality rate of the virus can only be roughly estimated.
6. Current estimates from studies that have had “captive populations” (sailors on the aircraft carrier Theodore Roosevelt, nursing home and homeless shelter populations, prison inmates and repatriated populations from cruise ships and hot spots,) have estimated that the rate of asymptomatic individuals (people who never develop symptoms) is about 40 percent. That is, in the general population, it is likely that 40 percent of people will get Coronavirus and will never have symptoms.
7. A pre-symptomatic person is someone who has the virus, has no symptoms, but will eventually get symptoms. An asymptomatic person does not have and will not develop symptoms
8. At the present time, remdesivir is the only medication that has been shown to affect the disease course, shortening hospitalization time by a few days.
Corticosteroids, specifically decadron, are indicated for patients who have severe symptoms. Experience has shown that early use of decadron or use in those with milder symptoms may cause more harm than benefit.
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All of the above indicates how imperative it is to use social distancing and mask wearing where appropriate. There is very likely a large reservoir of people who have the virus and do not have symptoms to warn them or others that they are contagious.
Quarantine for COVID19 positive people is necessary to allow the contagious phase to pass and to subsequently limit the risk of transfer of the virus to other people. Mask wearing and social distancing have been shown repeatedly to reduce the spread of virus and hospitalization and death rates. There are no other proven effective measures.
The writer is part of the primary care provider team that treats patients at the Hampshire Memorial Hospital’s Multispecialty Clinic.