A new virus outbreak in China

The outbreak of a new viral infection that was first detected in Wuhan, China in December 2019 and is causing increasing alarm around the world. Officials in China have presently confirmed more than 4.500 cases of the virus and the death of some 100 people.

Researchers fear similarities to the 2002–03 epidemic of severe acute respiratory syndrome (SARS), that emerged in southern China and killed 774 people in 37 countries. Both are members of a large virus family, called coronaviruses, that also includes viruses responsible for the common flu.

China has taken unprecedented action to try to halt the outbreak including putting Wuhan and nearby cities on lockdown, restricting travel in and out of the cities. For now, the World Health Organization (WHO) has held off declaring a public-health emergency of international concern.

Authorities are working on the hypothesis that the virus originated in an unidentified animal or animals and spread to humans at an animal and seafood market in Wuhan, which is now closed. Identification of the animal source of the virus could help officials to control the current outbreak and gauge its threat.

Genetic sequencing suggests that the Wuhan virus is related to coronaviruses that circulate in bats, including SARS and its close relatives. But other mammals can transmit these viruses. SARS was probably spread to humans by civet cats.

One of the unanswered questions is whether people without symptoms can infect others. A study of a cluster of six infections in a family in Shenzhen identified a child who was infected with the virus but showed no symptoms. If such asymptomatic cases are common and these individuals can spread the virus, then containing its spread will be much more difficult, researchers say. Key to controlling the SARS virus was the fact that few cases were asymptomatic.

No drugs have been shown to be effective in treating SARS or other coronavirus infections in humans, and no vaccines aimed at preventing these infections have been developed so far.

A team at China’s National Engineering Research Center for the Emergence Drugs in Beijing is working on finding therapies that would work by blocking the receptor on human cells that the virus latches on to and uses to infect the cells. A comparison of the SARS and new China virus sequences, published on the 16^th of January, found that they probably bind to the same receptor. The team is hoping to revive efforts to develop treatments for SARS and adapt them in a bid to develop a drug that could work against the latest virus.

Another researcher who has been developing drugs for coronaviruses since the SARS outbreak is hoping to test drug candidates in animal models of the Wuhan virus.

Chinese authorities are also testing whether existing HIV drugs can treat the infection. Ritonavir and Liponavir, which are approved to treat HIV, are being given to people with pneumonia caused by the coronavirus, according to media reports and a statement by the Beijing branch of China’s National Health Commission.