Virus basics: What are superspreader events and why do they happen? Your COVID-19 questions answered

No decision has been made, but the consensus among many experts in the U.S. and globally is that health care workers should be first, said Sema Sgaier of the Surgo Foundation, a nonprofit group working on vaccine allocation issues.

What does COVID-19 vaccine effectiveness mean? It refers to the likelihood that a coronavirus shot will work in people.

You have some immunity, but how much and for how long are big unanswered questions.

There's evidence that reinfection is unlikely for at least three months even for people who had a mild case of COVID-19. That's how long New York City researchers found stable levels of protective antibodies in a study of nearly 20,000 patients of the Mount Sinai Health System.

It depends on where you live and the precautions you and the gym take.

If cases of COVID-19 are poorly controlled where you live, experts say it's best to stay away. But if you live in an area where the spread is being contained, there are ways to minimize risk when going for a workout.

Does a face mask protect me, or just the people around me? It likely provides protection for both.

Employers are generally not required to tell workers when someone in the workplace has tested positive for the coronavirus.

Pick one that contains mostly alcohol, and has few other ingredients.

The U.S. Centers for Disease Control and Prevention says hand sanitizers should be at least 60% ethyl alcohol or 70% isopropyl alcohol. Other approved ingredients may include sterile distilled water, hydrogen peroxide and glycerin, according to the U.S. Food and Drug Administration.

No. Health officials don't recommend the clear plastic barriers as a substitute for masks because of the lack of research on whether they keep an infected person from spreading viral droplets to others.

There are three broad categories of coronavirus tests in the U.S. Two diagnose whether you have an active infection, and a third indicates if you previously had the virus.

Whether students have to wear masks, and the trouble they could face if they don't, depends on where they go to school.

The U.S. Centers for Disease Control and Prevention encourages masks for most students, especially when they are less than 6 feet apart. The exceptions are children younger than 2 and those with breathing problems or who can't remove the mask without help.

It's impossible to tell without a test. Influenza and COVID-19 have such similar symptoms, you may need to get tested to know what's making you miserable.

It appears the virus can spread among children and teens, but how easily may vary by age. Research is still underway, but children under age 10 seem to be less likely than older kids to transmit the virus to other children and adults.

Children generally don't appear to get sick or experience symptoms as often as adults when they're infected. Some evidence suggests that may be particularly true for younger kids. That might help explain why they appear less likely to spread the virus — they're less likely to be coughing and sneezing.

We're still learning, but it seems that much of the spread of the coronavirus has been caused by what disease trackers call superspreader events.

That's when a single person infects a large number of other people, or when a gathering is linked to a large number of cases.

The flu vaccine protects you from seasonal influenza, not the coronavirus — but avoiding the flu is especially important this year.

Health officials and medical groups are urging people to get either the flu shot or nasal spray, so that doctors and hospitals don't face the extra strain of having to treat influenza in the midst of the coronavirus pandemic.

There are several, and which one is best depends on how sick someone is.

For example, steroids such as dexamethasone can lower the risk of dying for severely ill patients. But they may do the opposite for those who are only mildly ill.

Health experts recommend wearing masks in public and keeping your distance from others in most cases, but whether you should do both could depend on the situation.

"There's no invisible force field at 6 feet," said Saskia Popescu, an infectious disease expert at George Mason University.

Even though it's known as a respiratory virus, doctors believe the coronavirus can directly infect the heart muscle and cause other problems leading to heart damage.

In some people, as COVID-19 decreases lung function, it may deprive the heart of adequate oxygen. Sometimes it causes an overwhelming inflammatory reaction that taxes the heart as the body tries to fight off the infection.

It's an intriguing idea, but there haven't been enough rigorous independent studies to establish whether antiviral masks are better at protecting wearers or preventing the spread of the virus.

Their specifics vary, but many antiviral masks are supposed to be made or coated with materials that have extra virus-fighting properties, such as copper.

Not really.

The World Health Organization says the virus can be transmitted in any kind of weather and that there is no reason to believe that cold weather can kill it.

Will social distancing weaken my immune system? In short, no.