By this time, we’ve all been consumed by the coronavirus pandemic. We’ve learned a few things about virology, bureaucratic complexities, and economic fragility. We’ve also learned that many citizens missed the early-childhood lesson that opinions should probably have at least some basis in fact. Regardless, in order to get to a desired destination, a few facts never hurt. Here are some basics regarding the novel coronavirus, including a couple reminders about the testing.
The Virus
Viruses are particles that contain genetic information (DNA or RNA) surrounded by a shell of protein and sometimes another envelope made of lipids and protein. Viruses do not have the machinery to make copies of themselves. In fact, there is debate as to whether or not they should be considered as life-forms. That said, viruses are quite adept at infecting cells (including human cells) and hijacking the cellular machinery to then make copies of themselves.
Coronaviruses comprise one type of virus that is found in nature. This group of viruses contains RNA as the genetic material, and several strains have been known to cause respiratory infections in humans, with symptoms generally limited to the “common cold.”
The current coronavirus pandemic is being caused by a strain to which humans had not been previously exposed. The official name of this coronavirus is SARS-CoV-2, and the disease that it causes is referred to as COVID-19.
The Disease
COVID-19 can range anywhere from completely asymptomatic (no symptoms) to lethal. Those who are older and/or have other medical issues can have more difficulty with the infection.
Avoiding rapid spread of the virus is key to limiting loss of life, both by protecting the vulnerable and preventing the exhaustion of healthcare resources. As such, the preventative measures of social distancing, hand washing, and mask wearing have been widely adopted. Eventually, the hope is that newly discovered vaccines will provide widespread immunity against the virus.
Testing
Until vaccines can be administered widely, identification of those with COVID-19 is important in order to limit their ability to unknowingly spread the virus to others. Testing for the presence of the virus is key in this regard. Much confusion has arisen regarding this process due to a wide variety of tests being available, uncertainty regarding exactly who should be tested, a collective lack of biology knowledge, and the unwilful and willful spread of misinformation.
Certain undebatable facts about testing do exist. Active infection (with or without symptoms) with SARS-CoV-2 can be confirmed by using two different types of tests.
- PCR (or RT-PCR) test. This test detects the presence of viral RNA. It is considered to be the most sensitive test – in other words, the risk of a false negative is low.
- Antigen test. This test detects part of a protein on the surface of the virus. (An antigen is something that can trigger an immune response, in this case part of a protein.) The antigen test is not felt to be as sensitive, raising concerns for false negatives. That said, the ease of use and rapid results are appealing.
Although only two types of tests exist to detect active infection, many different manufacturers can make these tests. Different testing protocols may require the patient sample to be collected in different ways, with examples being a nasopharyngeal swab (back of the nose), a nasal swab, a throat swab, and a saliva sample. Depending on the exact test used and where the test is done, results may be available at the point of care or may take several days to become available.
A third type of test detects evidence of an immune response, namely the production of antibodies, against the virus. This antibody test, which is acquired via a blood sample, cannot speak to the timing and activity of infection. A positive result simply indicates exposure to the virus at an unspecified time in the past. It remains unclear how long these antibodies can protect against future infection.
Knowledge continues to evolve rapidly. As has occurred throughout the history of mankind, new insights may contradict prior information.
