Within weeks, the virus has infected more people than Severe Acute Respiratory Syndrome (SARS) did in months. On Jan. 30, the World Health Organization declared the outbreak a global emergency.
The chart below shows the cumulative number of cases starting from the day that symptoms were documented for the first case. When compared to the new virus, the spread of SARS took much longer to gain momentum. Middle East Respiratory Syndrome (MERS) that first emerged in Saudi Arabia in 2012, took eight years to infect almost 2,500 people.
Confirmed infections since the first case.
Image: Reuters
The latest statistics indicate a fatality rate of about 2.2%, but disease experts say the actual rate may be higher or lower as there are likely more unconfirmed cases.
The SARS virus killed about 10% of all infected individuals, while the MERS outbreak identified in 2012 had a fatality rate of around 35%.
Fatality rate
Image: Reuters
Disease experts caution that it will take several more weeks to be confident of how the new virus behaves given how quickly it has spread and the fact that a reliable diagnostic test has only recently been introduced.
“Not everybody is being seen, not everybody is being tested,” said Dr. William Schaffner, professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center in Nashville.
“All the experts, myself included, tell the public that there is much we don’t know about this virus and we are learning as we go along. That is not so reassuring.”
Some experts question whether the new virus shares similarities with seasonal flu, which has a low mortality rate but infects so many people that more than half a million may die from it each year, according to global health estimates.
