As outbreaks of the new coronavirus that first emerged in China continue to spread in more than 100 countries — particularly those experiencing winter — one of the biggest unanswered questions is how it will behave in warmer weather.

Like influenza, the new disease is a respiratory infection belonging to a family of viruses that typically survive longer in colder environments. Most people experience only mild or moderate symptoms, such as fever and cough, but older adults and people with existing health problems may have more severe illnesses, including pneumonia.

Donald Trump suspended travel from Europe to the United States for 30 days on Wednesday in an "aggressive" effort to halt the spread of the novel coronavirus pandemic.

The United States is weighing a ban on travelers from Europe to slow the spread of the coronavirus, a senior U.S. official said Wednesday.

Iran is doing the best it can to control the spread of the coronavirus outbreak, but needs more support, the head of the World Health Organization said Wednesday.

"Iran is doing its best... We are trying to mobilize more support for Iran," WHO chief Tedros Adhanom Ghebreyesus told reporters in Geneva, adding that the country needed more supplies.

The World Health Organization called the new coronavirus outbreak a pandemic on Wednesday, issuing a grim warning that the global spread and severity of the illness was due to "alarming levels of inaction."

The number of confirmed novel coronavirus cases in Qatar jumped by 238 to 262 on Wednesday, the health ministry said, warning that they were likely a result of community transmission.

Iran's senior vice president and two other Cabinet members have contracted the new coronavirus, a semiofficial news agency reported Wednesday as the death toll in the Islamic Republic from the outbreak rose by 62 to 354.

The report by the Fars news agency, believed to be close to Iran's paramilitary Revolutionary Guard, comes as President Hassan Rouhani took control of the country's much-criticized response to the virus and the COVID-19 illness it causes. Authorities announced that there were some 9,000 confirmed cases of the virus across Iran.

Coronavirus infections in Spain have passed the 2,000 mark with 47 deaths, the health ministry announced on Wednesday, making it Europe's second most severe outbreak after Italy. 

European nations on Wednesday shut schools and universities and slapped  more restrictions on travel, sport and cultural events over the surging coronavirus outbreak, as more countries announced deaths from the epidemic.

Chancellor Angela Merkel vowed Wednesday to do everything it takes to tame  the coronavirus crisis, signalling she is even ready to suspend the cherished dogma of keeping Germany's budget balanced.