The news that one person is believed to have died and another is in critical condition from a new SARS-like respiratory illness has the public on edge. But how concerned should we really be? Here are some of the facts, and mysteries, about the virus.

What is a coronavirus?

Various strains of coronavirus affect animals and humans. The human strains are responsible for ailments such as the common cold, viral gastroenteritis and Severe Acute Respiratory Syndrome (SARS). They are named for the solar crown-like rays that fan out when the virus is viewed under a microscope. Coronaviruses were first identified in the mid-1960s.

How many cases are there of this new strain?

So far, public health officials have identified two cases between July and September of this year: a 60-year-old Saudi national who died in Saudi Arabia, and a 49-year-old Qatari national who had travelled to Saudi Arabia. The 49-year-old was diagnosed after he travelled to London, where he remains in hospital. The Health Protection Agency in the U.K. says it is also investigating “a small number of possible cases.”

What are the symptoms?

The various strains of coronavirus can cause an array of symptoms, from coughing, sneezing and sore throat to lower- and upper-respiratory infections, as well as gastrointestinal illness. The HPA said the two patients who acquired the new virus first reported having a fever, cough and shortness of breath. The man in hospital is suffering from pneumonia and kidney failure.

How is it transmitted?

Again, very little information exists about how the two victims fell ill. Generally, coronaviruses are contracted by inhaling infectious respiratory droplets, or from touching contaminated surfaces.

The HPA said preliminary tests show that people who came into contact with the two men have not contracted the virus, including health-care workers. The agency said “there is no specific evidence of ongoing transmission” so far.

Despite this, hospital officials in London are exercising extreme caution, keeping the patient in isolation and asking all staff treating him to wear protective equipment.

How is it treated?

As the virus has just been discovered, a treatment protocol has yet to be established. A vaccine is also not available.

How did this new strain evolve?

It’s not yet clear, but new viruses can be a mutation of an existing virus. A new infection may also be caught from an “infectious agent,” like bacteria or another virus, circulating in the animal population, according to the HPA. The agency says that at this stage, there is no evidence to suggest that the virus came from an animal.

What does the World Health Organization say?

The WHO says it is still obtaining further information about the novel virus “to determine the public health implications of these two confirmed cases.” As of yet, the agency has not issued any travel restrictions.