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The Coronavirus: What Scientists Have Learned So Far The Coronavirus: What Scientists Have Learned So Far
(1 day later)
A novel respiratory virus that originated in Wuhan, China, has spread quickly throughout the country and to two dozen other nations, leaving many experts to fear a pandemic may be on the way. A novel respiratory virus that originated in Wuhan, China, has spread to more than 30 countries in Asia, Europe and the Middle East, leaving many experts to fear a pandemic may be on the way.
So far, most of those infected with the virus have been in China. Most of the deaths have been there, as well.So far, most of those infected with the virus have been in China. Most of the deaths have been there, as well.
Both the World Health Organization and the United States have declared public health emergencies because of the virus’s spread, and both have offered China technical assistance and expertise to investigate and contain the outbreak.Both the World Health Organization and the United States have declared public health emergencies because of the virus’s spread, and both have offered China technical assistance and expertise to investigate and contain the outbreak.
Much is still unknown about the virus, including two factors that are pivotal to predicting the global human toll: how easily the virus spreads from person to person, and how many of those infected develop severe disease that can lead to death. Researchers returning from a W.H.O. mission to China said this week that the lockdown and prevention measures put in place last month seemed to have helped curb the pace of infections in the country.
In late January, W.H.O. officials said that the vast majority of those infected in China — 82 percent — had mild illness, while 15 percent had developed severe illness, and 3 percent had become critically ill. Those with severe illness developed pneumonia and respiratory failure. Experts have estimated that up to 2 percent of infected people have died. The daily tally of new cases there peaked and then plateaued between Jan. 23 and Feb. 2, and has steadily declined since.
The precise dimensions of the outbreak are hard to know. Not all of the infected have received a diagnosis, and China seems to have changed its definition of a “confirmed” case to include people who have pneumonia, as observed on CT scans, for any reason. But much remains unknown about the virus, including two factors that are pivotal to predicting the global human toll: how easily the virus spreads from person to person, and how many of those infected develop severe disease that can lead to death.
Experts cannot yet say who is at greatest risk for life-threatening disease, and what factors might be protective against the illness. Children seem much less likely to develop severe illnesses than middle-aged and older men, and people who have underlying health problems like Type 2 diabetes. The precise dimensions of the outbreak are hard to know. It is possible that not all of the infected have received a diagnosis, and experts have raised questions about how accurately cases are being recorded in China. Earlier this month China changed the way it counted cases, then changed it back again.
The United States is barring entry by most foreign nationals who have recently visited China. Hundreds of Americans returning from Wuhan and Hubei Province, the epicenter of the outbreak, have been quarantined. In the United States, there are more than 50 coronavirus cases in isolation, but the risk to most Americans is still low.
Federal health officials are urging Americans to avoid all travel to China.
“This is a very serious public health situation, and the C.D.C. and federal government have and will continue to take aggressive action to protect the public,” said Dr. Nancy Messonnier, director of the National Center for Immunization and Respiratory Diseases.
There are 15 cases of the coronavirus in the United States, but for now the risk to Americans is low.
Here’s what scientists have learned so far about the coronavirus and the outbreak.Here’s what scientists have learned so far about the coronavirus and the outbreak.
Coronaviruses are named for the spikes, which resemble a crown or the sun’s corona, that protrude from their surfaces. They can infect both animals and people, and can cause illnesses of the respiratory tract. Coronaviruses are named for the spikes that protrude from their surfaces, resembling a crown or the sun’s corona. They can infect both animals and people, and can cause illnesses of the respiratory tract.
Updated Feb. 25, 2020 At least four types of coronaviruses cause very mild infections every year, like the common cold. Most people get infected with one or more of these viruses at some point in their lives.
The infections can range from the common cold to dangerous conditions like Severe Acute Respiratory Syndrome, or SARS, which sickened thousands of people around the world — and killed nearly 800 — during an outbreak in 2003. Middle East Respiratory Syndrome, or MERS, first reported in Saudi Arabia in 2012, is also caused by a coronavirus. Another coronavirus that circulated in China in 2003 caused a more dangerous condition known as Severe Acute Respiratory Syndrome, or SARS. The virus was contained after it had sickened 8,098 people and killed 774.
The virus itself has been named SARS-CoV-2. The disease it causes is called Covid-19. Updated Feb. 26, 2020
It is hard to accurately assess the lethality of a new virus, and some scientists said initially that this new coronavirus appeared to be less severe than SARS or MERS. Middle East Respiratory Syndrome, or MERS, first reported in Saudi Arabia in 2012, is also caused by a coronavirus.
But the authorities in Wuhan apparently muzzled doctors who were first to recognize the new infection, and they may not have been fully transparent about the number of infections and deaths even after the alarm was raised. The leaders of both Hubei Province and Wuhan have been fired by top officials in Beijing. The new virus has been named SARS-CoV-2. The disease it causes is called Covid-19.
It is also not clear whether cases and deaths in China are being carefully tracked and reported. Diagnostic kits and other health resources have been in short supply in the affected regions. It is hard to accurately assess the lethality of a new virus. It appears to be less often fatal than the coronaviruses that caused SARS or MERS, but significantly more so than the seasonal flu. The death rate was over 2 percent, in one recent study. About 5 percent of the patients who were hospitalized had critical illnesses.
A sudden change in how cases are diagnosed added 14,800 overnight to the tally of the infected in Hubei Province, perplexing the W.H.O. and other experts, who have asked for clarification. Children seem less likely to be infected with the new coronavirus, while middle-aged and older adults are disproportionately infected.
Scientists don’t know who is most susceptible to the new coronavirus. Children seem less likely to be infected. Middle-aged men seem to have been disproportionately infected, according to some studies. Men are more likely to die from an infection compared to women, possibly because they produce weaker immune responses and have higher rates of tobacco consumption, Type 2 diabetes and high blood pressure than women, which may increase the risk of complications following an infection.
“Whenever a new virus comes out, it takes a while to learn about it,” said Dr. Julie Vaishampayan, chairwoman of the public health committee of the Infectious Diseases Society of America. Right now, she said, “the information about coronavirus is changing rapidly.” “This is a pattern we’ve seen with many viral infections of the respiratory tract — men can have worse outcomes,” said Sabra Klein, a scientist who studies sex differences in viral infections and vaccination responses at the Johns Hopkins Bloomberg School of Public Health.
Most respiratory viruses are transmitted through coughing and sneezing. Experts believe that an infected animal may have first transmitted the virus to people at a market that sold live fish, animals and birds in Wuhan. The market was later shut down and disinfected, making it nearly impossible to investigate which animal may have been the exact origin.
Though the Chinese authorities initially played down the likelihood of human-to-human transmission, it has now become clear that there is significant and sustained transmission among people. Indeed, the coronavirus seems to be highly contagious. Bats are considered a possible source, because they have evolved to coexist with many viruses, and they were found to be the starting point for SARS. It is also possible that bats transmitted the virus to an intermediate animal, such as pangolins, which are consumed as a delicacy in parts of China, and may have then passed on the virus to humans.
Cases of transmission from asymptomatic people have been documented. That’s “bad news,” said Dr. William Schaffner, an expert in infectious diseases at Vanderbilt University Medical Center in Nashville. The outbreak grew because of human-to-human transmission.
When people don’t know they are infected, “they’re up and about, going to work or the gym or to religious services, and breathing on or near other people,” Dr. Schaffner said. People infected with the virus produce tiny respiratory droplets when they breathe, talk, cough or sneeze, allowing the virus to travel through the air.
A major concern is that with both SARS and MERS, a few patients inexplicably became “superspreaders” who infected huge numbers of people. Most respiratory droplets fall to the ground within a few feet. People who are in close contact with those infected, particularly family members and health care workers, may catch the virus this way.
Health care workers are particularly vulnerable. At a hospital in Seoul in 2015, one man with MERS transmitted it to 82 patients. Scientists don’t know how long the new coronavirus can live on surfaces, and preliminary research suggests that hot and humid environments may not slow down the pathogen’s spread. Warm weather does tend to inhibit influenza and milder coronaviruses.
On Jan. 8, The New York Times reported that Chinese researchers had identified a new coronavirus as the pathogen behind a mysterious illness that had sickened 59 people in Wuhan. Infected people may be able to pass on the new coronavirus even if they have few obvious symptoms, a study in Germany has found. That’s “bad news,” said Dr. William Schaffner, an expert in infectious diseases at Vanderbilt University Medical Center in Nashville.
The cases were linked to a market that sold live fish, animals and birds. The market was later shut down and disinfected. When people don’t know they are infected, “they’re up and about, going to work or the gym or to religious services, and breathing on or near other people,” he said.
Past outbreaks of similar illnesses, including SARS, are also believed to have emerged from live animal markets. The coronavirus that causes MERS is transmitted to humans by camels.
The animal that was the source of the new coronavirus is still not known, and the destruction of the Wuhan meat market has made the question nearly impossible to investigate. Symptoms of this infection include fever, cough and difficulty breathing or shortness of breath. The illness causes lung lesions and pneumonia. But milder cases may resemble the flu or a bad cold, making detection difficult.
Bats are considered a possible source, because they have evolved to coexist with many viruses, including coronaviruses. But it is very possible the virus was transmitted from bats to an intermediate animal, and then to humans. Patients may exhibit other symptoms, too, such as gastrointestinal problems or diarrhea. Current estimates suggest that symptoms may appear in as few as two days or as long as 14 days after being exposed to the virus.
Lately virologists have focused their attention on pangolins, an armadillo-like animal consumed as a delicacy in parts of China. Many suspect a pangolin was the intermediate host.
Symptoms of this virus include fever, severe cough and difficulty breathing or shortness of breath. The illness causes lung lesions and pneumonia. Milder cases may resemble the flu or a bad cold, making detection difficult.
Patients may exhibit other symptoms, too, such as gastrointestinal problems or diarrhea. The incubation period — the time from exposure to the onset of symptoms — is believed to be anywhere from 10 days to two weeks.
If you have a fever or a cough and recently visited China, or spent time with someone who did, see your health care provider. Call first, so the office can prepare for your visit and take steps to protect other patients and staff from potential exposure.If you have a fever or a cough and recently visited China, or spent time with someone who did, see your health care provider. Call first, so the office can prepare for your visit and take steps to protect other patients and staff from potential exposure.
There is a diagnostic test that can determine if you are infected. It was developed by the Centers for Disease Control and Prevention, based on genetic information about the virus provided by the Chinese authorities. There is a diagnostic test that can determine if you are infected. It was developed by the Centers for Disease Control and Prevention, based on genetic information about the virus provided by the Chinese authorities. At the moment, all patient samples that need to be tested for coronavirus are sent to the C.D.C. in Atlanta, delaying the time it takes to confirm results.
The C.D.C. sent diagnostic test kits to 200 state laboratories and roughly the same number in at least 30 other countries. Unfortunately, the kits were flawed, sometimes producing inconclusive results. The C.D.C. is manufacturing replacement versions. In early February, the C.D.C. sent diagnostic test kits to 200 state laboratories, but some of the kits were flawed and recalled. The C.D.C. is manufacturing replacement versions. Other countries are using test kits manufactured locally or sent out by the W.H.O.
The main treatment for coronavirus is supportive care, including making sure the patient is getting enough oxygen, and using a ventilator to push air into the lungs if necessary, Dr. Vaishampayan said. Once a coronavirus infection is confirmed, the treatment is mainly supportive, making sure the patient is getting enough oxygen, managing his or her fever and using a ventilator to push air into the lungs if necessary, said Dr. Julie Vaishampayan, chairwoman of the public health committee at the Infectious Diseases Society of America.
Patients should rest and drink plenty of fluids “while the immune system does its job and heals itself,” she said. Patients with mild cases are told to rest and drink plenty of fluids “while the immune system does its job and heals itself,” she said.
No drugs have been approved for any coronavirus diseases, including the new coronavirus, though an antiviral medication called remdesivir appears to be effective in animals and was used to treat a patient in Washington State. No drugs have been approved for any coronavirus diseases, including the new coronavirus, though an antiviral medication called remdesivir appears to be effective in animals and was used to treat the first American patient in Washington State. The National Institutes of Health is testing the drug on infected patients in a Nebraska hospital.
Chinese officials are experimenting with other antiviral drugs to treat the infection.Chinese officials are experimenting with other antiviral drugs to treat the infection.
A coronavirus vaccine is still months away — and perhaps years. While new technology, advancements in genomics and improved global coordination have allowed researchers to act quickly, vaccine development remains an expensive and risky process.A coronavirus vaccine is still months away — and perhaps years. While new technology, advancements in genomics and improved global coordination have allowed researchers to act quickly, vaccine development remains an expensive and risky process.
With each new outbreak, scientists typically have to start from scratch. After the SARS outbreak in 2003, it took researchers about 20 months to get a vaccine ready for human trials. (The vaccine was never needed, because the disease was eventually contained.) After the SARS outbreak in 2003, it took researchers about 20 months to get a vaccine ready for human trials. (The vaccine was never needed, because the disease was eventually contained.)
By the time of the Zika outbreak in 2015, researchers had brought the vaccine development timeline down to six months.By the time of the Zika outbreak in 2015, researchers had brought the vaccine development timeline down to six months.
Now, they hope that work from past outbreaks will help cut the timeline further. Scientists at the National Institutes of Health and several companies are working on vaccine candidates.Now, they hope that work from past outbreaks will help cut the timeline further. Scientists at the National Institutes of Health and several companies are working on vaccine candidates.
Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, said a preliminary clinical trial might get off the ground in as little as three months. But researchers would still need to conduct extensive testing to prove a vaccine was safe and effective.Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, said a preliminary clinical trial might get off the ground in as little as three months. But researchers would still need to conduct extensive testing to prove a vaccine was safe and effective.
Even under the best circumstances, it could take at least a year — maybe longer — for a vaccine to become available. The best thing you can do to avoid getting infected is to follow the same general guidelines that experts recommend during flu season, because the coronavirus spreads in much the same way. Wash your hands frequently throughout the day. Avoid touching your face, and maintain a distance from anyone who is coughing or sneezing.
If you have a respiratory infection, wearing a mask helps protect the people around you from illness by reducing the risk that you will spread the infection. And wearing a surgical mask may somewhat protect you from infection in a crowd if there is an outbreak.
But, generally, surgical masks are not closefitting enough to filter all the air you are breathing in, and heavy-duty N95 respirators are extremely uncomfortable.
Experts recommend washing your hands frequently throughout the day. Avoid touching your face, and maintain a distance from anyone who is coughing or sneezing.
At the moment, the risk of infection with the new coronavirus in the United States “is way too low for the general public to start wearing a face mask,” said Dr. Peter Rabinowitz, co-director of the University of Washington MetaCenter for Pandemic Preparedness and Global Health Security.At the moment, the risk of infection with the new coronavirus in the United States “is way too low for the general public to start wearing a face mask,” said Dr. Peter Rabinowitz, co-director of the University of Washington MetaCenter for Pandemic Preparedness and Global Health Security.
But, he added, “if you have symptoms of a respiratory illness, wearing a mask reduces the risk of infecting others.”But, he added, “if you have symptoms of a respiratory illness, wearing a mask reduces the risk of infecting others.”
No. The State Department has warned Americans not to go to China unless it is absolutely essential. Airlines have curtailed service to mainland China. If you must go and manage to get there, be aware that you may be quarantined for two weeks on return. The C.D.C. has warned Americans not to travel to China or South Korea unless it is absolutely essential. Older adults and people with chronic medical conditions should also consider postponing travel to Italy, Iran and Japan, where there are clusters of coronavirus transmission.
Many other countries have enacted travel restrictions and bans. Governments around the world have been screening incoming passengers from China for signs of illness. Many have gone further, barring entry to people from China altogether. Russia and Mongolia closed most of their borders with China. Australia evacuated citizens from Wuhan and quarantined them on Christmas Island. Many countries have also enacted travel restrictions and bans, closing their doors to people from countries with sustained transmission of the virus. Governments around the world have been screening incoming passengers for signs of illness.
China has taken drastic action to bar people from leaving affected areas. Tens of millions are effectively cordoned off in cities. Residents have been told to remain in their homes. Officials in China are using cellphone data to track and intercept those who have been to Hubei Province. Airlines and cruise lines have canceled service to many Asian destinations.
In recent weeks, government workers have gone door to door to round up people who are infected, placing them in stadiums and other buildings that have been converted to makeshift hospitals. W.H.O. officials have credited lockdown measures China imposed in late January for averting the spread of more cases from Wuhan. China sealed off cities, shut down businesses and schools, and ordered residents to remain in their homes. Officials use cellphone data to track and intercept those who have been to Hubei Province.
China agreed to permit a team of W.H.O. experts into the country to offer expertise. The C.D.C. has offered to participate, although it is not clear that China will accept them. In recent weeks, government workers have gone door-to-door to round up people who are infected, placing them in stadiums and other buildings that have been converted to makeshift hospitals. Now, official reports suggest that new cases in China are waning.
Reporting was contributed by Knvul Sheikh and Daniel Victor. But there is growing fear that containment may no longer be possible.
Clarence Tam, an assistant professor of infectious diseases at the School of Public Health at the National University of Singapore, said the surge of cases in multiple countries was “concerning because we know the transmissions are spreading at a fast rate.”
“We’ve learned some things of this new virus for the past couple of weeks that make it seem unlikely that containment will be a strategy that will completely stop this virus,” he added.
There is benefit to delaying its spread as long as possible. Containing the virus may buy health officials more time to stock hospitals with test kits and respirators, and develop drugs for treatment and a vaccine.
But the ability of nations to prepare for the arrival of coronavirus cases will depend largely on the strength of their health systems, capacity to conduct tests and effectiveness in communicating updates to the public.
“We have been dealing with flu for decades and even now it seems some countries don’t even have a policy for influenza preparedness,” said Leo Poon, head of the University of Hong Kong’s public health laboratory sciences division. “Not to mention something which is new to them. That’s a problem.”
Reporting was contributed by Daniel Victor from Hong Kong.