Molecular PCR tests directly detect the virus’s presence rather than the presence of the body’s immune response or antibodies. By detecting viral RNA, which will be present in the body before antibodies form, the molecular PCR tests can tell whether someone has the virus very early on and whether they are infectious.
An antibody test tells us what proportion of the population has been infected. It won’t tell you who is infected because the antibodies are generated after a week or two, after which time the virus should have been cleared from the system. But it tells you who has been infected and who is likely to be immune to the virus.
Antibody testing measures the body’s immune response to an infection and can provide insights into an individual’s prior exposure to COVID-19 and may indicate a prior infection that may be resolved or is still resolving, and/or protection against re-infection (“protective immunity”). According to a recent white paper summary issued by the American Clinical Laboratory Association (ACLA), when used appropriately, antibody testing may help determine the number of individuals who have been infected with SARS-CoV-2.
By supporting screening for individuals using serology, healthcare professionals can provide a more detailed assessment of the true rate of infection and better understand the case fatality rate to help inform public health strategies. Serologic testing could also be used to support future vaccine development and contact tracing (the process of identifying persons who may have come into contact with an infected person and subsequent collection of further information about these contacts) to stop the spread of the infection in the community.
In medical diagnosis, test sensitivity is a test’s ability to correctly identify those with the disease (true positive rate). In contrast, test specificity is the test’s ability to accurately identify those without the disease (true negative rate).
Wearing a face mask is certainly not an iron-clad guarantee that you won’t get sick—viruses can also transmit through the eyes, and tiny viral particles, known as aerosols, can penetrate masks. However, masks effectively capture droplets, which is the main transmission route of coronavirus. Some studies have estimated a roughly fivefold protection versus no barrier alone (although others have found lower effectiveness levels).
If you are likely to be in close contact with someone infected, a mask cuts the chance of the disease being passed on. If you’re showing coronavirus symptoms, or have been diagnosed, wearing a mask can also protect others. So, masks are crucial for the health and social care workers looking after patients and are also recommended for family members who need to care for someone who is ill—ideally, both the patient and caregiver should have a mask.
If you are at higher risk of getting very sick from COVID-19, you should: stock up on supplies; take everyday precautions to keep space between yourself and others; when you go out in public, keep away from others who are sick; limit close contact and wash your hands often; and avoid crowds, cruise travel, and non-essential travel. If there is an outbreak in your community, stay home as much as possible. Watch for symptoms and emergency signs. If you get sick, stay home and call your doctor.