The Coronavirus: What Scientists Have Learned So Far

The Coronavirus: What Scientists Have Learned So Far

A novel respiratory virus that originated in Wuhan, China, has spread to over 100 countries in Asia, Europe, North America and the Middle East. More than 100,000 have been infected, leaving many experts to fear a pandemic may already be underway.

The Coronavirus: What Scientists Have Learned So Far

so far, most of those infected with the virus have been in China, and most of the deaths have occurred there, as well. But now South Korea, Iran and Italy are coping with significant outbreaks. Italy has imposed restrictions throughout the country.

The United States has seen more than 800 cases and about 30 deaths. Many do not seem linked to international travel, which suggests that the virus is spreading in communities. The coronavirus may have infected up to 1,500 people in the Seattle area alone, hints a model produced by infectious disease experts. The number of infections may be doubling every six days, according to another model, but the nation’s capacity to test for the infection has lagged.

Much remains unknown about the virus, including how many people may have very mild or asymptomatic infections, and whether they can transmit the virus. The precise dimensions of the outbreak are hard to know.

Here’s what scientists have learned so far about the virus and the outbreak.

What is a coronavirus?

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.

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.

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.

Middle East Respiratory Syndrome, or MERS, first reported in Saudi Arabia in 2012, is also caused by a coronavirus.

The new virus has been named SARS-CoV-2. The disease it causes is called Covid-19.

How dangerous is it?

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 fatality rate was over 2 percent, in one study. But government scientists have estimated that the real figure could be below 1 percent, roughly the rate occurring in a severe flu season.

About 5 percent of the patients who were hospitalized in China had critical illnesses.

Children seem less likely to be infected with the new coronavirus, while middle-aged and older adults are disproportionately infected.

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.

“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.