From Harvard Medical School..... (click on the read to read the full article.)

What are the chances that a coronavirus test will tell me I am not infected when I actually am?

The chances that a coronavirus test will give you a false negative (indicating that you are not infected when you actually are infected) depend upon the type of test you have and when in the course of your infection the test is performed. There are two main types of tests:

• nasal/throat swab tests and saliva tests, both of which detect the virus itself
• blood tests that detect antibodies that your immune system produces in response to the infection.

If you get the nasal/throat swab or saliva test, you will get a false negative test result:

• 100% of the time on the day you are exposed to the virus. (There are so few viral particles in your nose or saliva so soon after infection that the test cannot detect them.)
• About 40% of the time if you are tested four days after exposure to the virus.
• About 20% of the time if you develop symptoms and are tested three days after those symptoms started.

This possibility of a false negative test result is why anyone who has symptoms that could be due to COVID-19, or has been exposed to someone known to be infected, must isolate even if they test negative for coronavirus.

How soon after I'm infected with the new coronavirus will I start to be contagious?

The time from exposure to symptom onset (known as the incubation period) is thought to be three to 14 days, though symptoms typically appear within four or five days after exposure.

We know that a person with COVID-19 may be contagious 48 to 72 hours before starting to experience symptoms. Emerging research suggests that people may actually be most likely to spread the virus to others during the 48 hours before they start to experience symptoms.

If true, this strengthens the case for face masks, physical distancing, and contact tracing, all of which can help reduce the risk that someone who is infected but not yet contagious may unknowingly infect others.

For how long after I am infected will I continue to be contagious? At what point in my illness will I be most contagious?

People are thought to be most contagious early in the course of their illness, when they are beginning to experience symptoms, especially if they are coughing and sneezing. But people with no symptoms can also spread the coronavirus to other people if they stand too close to them. In fact, people who are infected may be more likely to spread the illness if they are asymptomatic, or in the days before they develop symptoms, because they are less likely to be isolating or adopting behaviors designed to prevent spread.

Most people with coronavirus who have symptoms will no longer be contagious by 10 days after symptoms resolve. People who test positive for the virus but never develop symptoms over the following 10 days after testing are probably no longer contagious, but again there are documented exceptions. So some experts are still recommending 14 days of isolation.

One of the main problems with general rules regarding contagion and transmission of this coronavirus is the marked differences in how it behaves in different individuals. That's why everyone needs to wear a mask and keep a physical distance of at least six feet.

Here is a more "scientific" way to determine if you are no longer contagious: have two nasal-throat tests or saliva tests 24 hours apart that are both negative for the virus.

If I get sick with COVID-19, how long until I will feel better?

It depends on how sick you get. Those with mild cases appear to recover within one to two weeks. With severe cases, recovery can take six weeks or more.

Some people may experience longer-term physical, cognitive, and psychological problems. They may alternately improve and worsen over time, and can include a variety of difficulties, from fatigue and trouble concentrating to anxiety, muscle weakness, and continuing shortness of breath.

How long after I start to feel better will be it be safe for me to go back out in public again?

We don't know for certain. Based on the most recent research, people may continue to be infected with the virus and be potentially contagious for many days after they are feeling better. But these results need to be verified. Until then, even after 10 days of complete resolution of your symptoms, you should still take all precautions if you do need to go out in public, including wearing a mask, minimizing touching surfaces, and keeping at least six feet of distance away from other people.