What experts know (and still don’t know) about the spread, symptoms, immunity, contagiousness, and more

COVID-19 is a rapidly spreading disease, caused by a coronavirus that jumped from animals to humans in late 2019. Here are the most pressing and recent questions related to the fast-moving pandemic.

When will the coronavirus pandemic end?

There’s some speculation that the spread of the coronavirus will subside with summer’s warmer weather, as happens with the flu and the common cold. But since the virus is brand new, health officials don’t know yet if that will also be the case for COVID-19. Not all viruses behave the same, and in fact, people can catch the flu and the common cold in summer, though it’s less prevalent. “At this time, we do not know whether the spread of COVID-19 will decrease when the weather warms up,” according to Harvard Medical School’s Coronavirus Resource Center. Currently, virus rates are dropping in China, where the outbreak first started spreading.

How does COVID-19 spread?

The coronavirus is thought to spread from person to person through handshakes, kisses, friendly embraces, and airborne respiratory droplets from a cough or sneeze — or even regular breathing, which is why the CDC and other health officials recommend staying at least six feet away from other people in public settings.

Disease-carrying droplets infect people primarily by entering the eye, nose, or mouth, hence the advice to avoid touching your face. The virus is also thought to persist on hard surfaces for a few hours or perhaps even a few days, making door handles, checkout counters, and shopping carts risky for transmission.

A new study, published March 17 in the New England Journal of Medicine, finds the coronavirus can remain viable and detectable for varying lengths of time on various surfaces:

• In aerosols (airborne droplets): up to 3 hours
• On copper: up to 4 hours
• On cardboard: up to 24 hours
• On plastic and stainless steel: up to two to three days

The research “suggests that people may acquire the virus through the air and after touching contaminated objects,” the authors write.

Can you spread the coronavirus if you don’t have symptoms?

Yes. A new study based on early cases in China suggests that for every known case of COVID-19, five to 10 other cases are not documented, and those people cause “stealth transmission” of the disease, the researchers reported on March 16 in the journal Science.

Tests have begun in labs around the world to seek both remedies or cures and a vaccine, which could take several months to develop and test.

“The explosion of COVID-19 cases in China was largely driven by individuals with mild, limited, or no symptoms who went undetected,” says study co-author Jeffrey Shaman, PhD, professor of environmental health sciences at Columbia University Mailman School. “Depending on their contagiousness and numbers, undetected cases can expose a far greater portion of the population to the virus than would otherwise occur.”

Are young people safe or immune from the virus?

No. However, it seems younger and healthier people handle the infection significantly better. “Older people and those with underlying medical problems, like high blood pressure, heart problems, or diabetes, are more likely to develop serious illness,” according to the World Health Organization (WHO). Even kids can get COVID-19. “Children tend to experience milder symptoms, such as fever, runny nose, and cough,” the Harvard resource center states. “Some children have had severe complications, but this has been less common.”

Meanwhile, preliminary data on U.S. cases with known ages (excluding people repatriated from other countries) through March 16, analyzed by the CDC, find younger adults who get the disease require hospitalization at a rate suggesting more serious outcomes than may have been perceived before. Among 2,449 people diagnosed with COVID-19, 508 were hospitalized, and among them:

• 9% were 85 or older
• 26% were 65–84
• 17% were 55–64
• 18% were 45–54
• 20% were 20–44

Further, among 121 of these people admitted to an intensive care unit (ICU), 12% were aged 20–44. Nine deaths were reported among people ages 20 to 64, with no further breakdown given within that broad age group. “These preliminary data also demonstrate that severe illness leading to hospitalization, including ICU admission and death, can occur in adults of any age with COVID-19,” the researchers conclude.

Can you get COVID-19 twice?

There are at least three news reports of people getting the disease a second time after recovering. But the possibility has not been studied, so there’s no clear answer yet whether the cases are real or perhaps involve faulty testing or some other unknown explanation.

“Most people would likely develop at least short-term immunity to the specific coronavirus that causes COVID-19,” according to the Harvard resource center. “However, you would still be susceptible to a different coronavirus infection. Or, this particular virus could mutate, just like the influenza virus does each year. Often these mutations change the virus enough to make you susceptible, because your immune system thinks it is an infection that it has never seen before.”

“It is likely that eventually [COVID-19] will become endemic, and most of us will get infected,” says Justin Lessler, an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health.

How deadly is the virus?

It’s still too early to say for sure, but it looks like COVID-19 is at least as deadly as seasonal flu, and maybe much more so. (Influenza typically kills about 0.1% of all people infected.) Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), said on March 11 that COVID-19 may be 10 times deadlier than seasonal flu.

Data from China suggests a COVID-19 death rate of around 0.2% for people ages 10 to 30, rising to 1.3% for people in their fifties, and up to 14.8% for people over 80. But since these figures are based on very early cases out of the disease epicenter in Wuhan, China, they might not be a representative picture.

New data from cases in Italy, published on March 17 by the Journal of the American Medical Association, suggests death rates by age groups, based on 22,512 known cases in the country:

• Under 30: 0
• 30–39: 0.3%
• 40–49: 0.4%
• 50–59: 1.0%
• 60–69: 3.5%
• 70–79: 12.5%
• 80–89: 19.7%
• >90: 22.7%
• Total: 7.2%

Again, actual rates may be lower since not all cases are diagnosed or reported.

Can people fully recover?

About 80% of people with COVID-19 fully recover without special treatment. A few need treatment and recover well. But about 17% get seriously ill and find breathing difficult.

Do ibuprofen and aspirin increase the risk for people with COVID-19?

France’s health minister claimed they do, saying these so-called nonsteroidal anti-inflammatory drugs (NSAIDs) worse COVID-19 symptoms, suggested acetaminophen instead for reducing fever. There is no research to back this claim, Fauci said March 18. “I have not seen any firm data to indicate there’s a problem or to prove there’s not a problem,” he said.

Full Story: What the Science Really Says About Ibuprofen and Coronavirus

What are the symptoms?

The characteristic symptoms of COVID-19 are fever, tiredness, and coughing. “Some patients may have aches and pains, nasal congestion, runny nose, sore throat, or diarrhea,” the WHO says.

But not every person develops all symptoms, and some people carry the disease without having any symptoms. See our symptom chart to learn more about the difference between COVID-19 and the cold and flu.

Importantly, anyone with fever, cough, and difficulty breathing should seek medical attention immediately, as should anyone with a fever above 104 degrees Fahrenheit, chest pains, blue lips, or severe dehydration. (See the CDC’s full list of emergency symptoms.)

How long are you contagious?

People may be contagious before symptoms start, but mostly when symptoms are present. Scientists are still trying to figure this out. Symptoms can take anywhere from two to 14 days to appear in someone who is infected and contagious. Recovery time, until symptoms are gone, varies based on how sick a person gets.

“Those with mild cases appear to recover within one to two weeks,” according to the Harvard resource center. “With severe cases, recovery can take six weeks or more.” Also, researchers have found viral genetic material in people after recovery. “It is safest to assume that you may be contagious for weeks after you recover.”

What is ‘herd immunity,’ and does it work?

The U.K. government recently announced it was exploring “herd immunity” as a way to battle the coronavirus. The idea is that a disease’s spread can be slowed or stopped if a high percentage of the population is immune, either through a vaccine or, if no vaccine is available, by having had the disease.

There are questions around how high that percentage needs to be and whether it can truly prevent outbreaks. But the notion of relying on herd immunity to stop COVID-19, rather than employing sensible preventive measures like those listed below, are heavily criticized by health officials.

“I’ve been talking to other academics, science journalists, private companies, & gov’t people all of today and still struggling to understand this,” tweeted Devi Sridhar, professor of global public health at the University of Edinburgh. “The gov’t seems to be following the flu playbook strategy. But this is not the flu. COVID-19 is much worse & health outcomes are sobering.”

Is there a cure or vaccine?

No. Despite rumors to the contrary, neither gargling with mouthwash nor eating garlic will help. Also, antibiotics do not work on viruses.

Here’s what the WHO says: “While some Western, traditional, or home remedies may provide comfort and alleviate symptoms of COVID-19, there is no evidence that current medicine can prevent or cure the disease. WHO does not recommend self-medication with any medicines, including antibiotics, as a prevention or cure for COVID-19.”

Tests have begun in labs around the world to seek both remedies or cures and a vaccine, which could take several months to develop and test.

The first clinical trial of a potential vaccine began on March 16, the NIAID announced. The Phase 1 study was “launched in record speed,” Fauci said. But determining the safety of the potential vaccine, and then its possible effectiveness, is expected to take at least a year.

What are the best ways to protect yourself and others?

From the CDC and other health officials:

• Stay home if you are sick.
• Avoid crowds and close contact with others.
• Cover your mouth/nose when you cough/sneeze, using a tissue (then toss it) or the inside of your elbow.
• Wash your hands often and properly with soap and water, scrubbing for 20 seconds.
• Use hand sanitizer only in a pinch, but know that while it is useful, it is not as effective as soap and water.
• Wear a face mask if you are sick to help prevent infecting others. (Here’s how to use face masks.) If you’re not sick, don’t wear one unless you are caring for someone who is sick.
• Disinfect frequently touched hard surfaces (doorknobs, counters, etc.) using bleach (1/3 cup per gallon of water) or a 70% alcohol solution or other disinfectants recommended by the EPA.

---

The coronavirus outbreak is rapidly evolving. To stay informed, check the U.S. Centers for Disease Control and Prevention and your local health department for updates. If you’re feeling emotionally overwhelmed, reach out to the Crisis Text Line.