As the new corona virus spreads, scientists around the world are working to learn more about the pathogen: what is it like? What are the consequences of an infection for the patient? New studies are published every week at an unprecedented rate and made available to the public free of charge.
Now Chinese teams of scientists have presented new data. In two studies in the specialist journal “Lancet”, they investigate the question of where 2019-nCoV comes from and how the genome differs from that of other corona viruses.
On the other hand, they describe the course of the disease in 99 patients who were treated with pneumonia infection in a clinic in Wuhan between January 1 and 20. Included are the 41 patients that the specialist journal reported about a week earlier. The doctors and researchers evaluated clinical records, laboratory results and X-rays and combined them with data on the outbreak.
In another study, published in the New England Journal of Medicine (NEJM), a team of Chinese scientists evaluated the course of the first 425 Wuhan patients whose infection was reported by January 22. The main focus was on how the outbreak developed.
Who is particularly at risk?
One question has arisen since the outbreak began: Who is particularly at risk? According to the new data Men affected more often than women, In the Lancet study, 67 percent of those infected were male, in the NEJM study it was 56 percent. Sars and Mers viruses also infect men more often than women. This could be because women generally have a better immune system.
The assumption that especially people with previous illnesses are affected seems to be confirmed – with all necessary caution. Every second of the 99 patients suffered from a chronic illness, especially of the cardiovascular system or the brain vessels.
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The The average age of all patients in both evaluations was slightly under 60 years. In the NEJM evaluation, almost every second infected person was 60 years or older. According to the researchers, the group of older men with previous illnesses represents a special risk group.
Another important finding: There were no children in the first 425 patients. This could mean they are less at risk of being infected, or the virus causes them to experience milder symptoms that do not necessarily mean they have to go to the hospital. This must be shown by further studies.
Most patients presented with fever and cough in the clinic, a third suffered from shortness of breath. Some had muscle or headaches or were confused. On the other hand, only four out of 99 had a runny nose. This fits with the assumption that the coronavirus 2019-nCoV mainly affects the deep airways. In three out of four cases, X-rays showed inflammation in both lungs.
How do currently available drugs work against the new viruses?
Three quarters of the patients were treated with antiviral drugs, such as the HIV drugs lopinavir and ritonavir. Most were given antibiotics in the event of a secondary infection with bacteria, and oxygen for breathing support.
Despite this treatment, the health of eleven patients deteriorated drastically in a short time. They developed a shortness of breath syndrome and died shortly afterwards of multiple organ failure. The first two dead were men, 61 and 69 years old, both had no underlying disease, but were long-time smokers.
Of the other nine dead, five were over 60 years old. By January 25, a third of the 99 patients had been discharged. 57 patients continued to be treated in the hospital. The authors write that confirms the assumption that especially older people with already weakened immune systems are at risk from the virus could be.
However, further data with many more patients and complete courses are needed to close the sometimes large gaps in knowledge. It is particularly important to identify patients as early as possible, for whom the disease could take a severe course.
A market as a probable origin, but the intermediate host is unknown
Another important question is where the outbreak started. About one in two patients in the smaller study had contact with the Huanan market before the illness, where live animals were offered and which is discussed as a possible origin of the outbreak.
Some of the patients worked there as sales people or managers. According to the other evaluation, at 55 percent, the majority of people diagnosed with the disease in 2019 had had contact with the market. In later cases, however, it was just under nine percent. The authors interpret this as evidence that the virus transmitted from person to person since mid-December has been.
Background about the corona virus:
Also for incubation period the scientists submit new data. According to this, an average went from infection to the first symptoms about five days, In some cases, however, it lasted more than two weeks. Experts believe that unlike Sars, patients are already contagious at this time.
The first German patient in Bavaria had probably been infected by a visitor from China who, according to her own information, had no complaints at that time. This makes it particularly difficult to identify infected people early on. The scientists therefore suggest actively searching for cases, such as in doctor’s offices or emergency rooms. According to their new data, a quarantine period of 14 days is justified.
How many people are infected?
And yet another key figure of the virus is important for experts in order to be able to assess the progress of an outbreak: the “basic reproduction number” R0. It indicates how many people, whose immune system has not yet developed protection against the pathogen, can infect an infected person on average.
According to their data, the researchers estimate R0 of the new coronavirus at 2.2. That would be the virus a little less contagious than Sars with an R0 of about 3. For comparison: an measles sufferer infects an average of 12 to 18 people. To contain an outbreak, R0 must be pushed to values below one.
The drastic quarantine measures in China should have exactly this goal. According to the researchers, these are likely to result in fewer cases being exported from Wuhan in the future. It is now a top priority to determine whether the virus spreads to other locations as quickly as it did in Asia.
Genetic analysis confirms the assumption: it is a virus from bats
In the meantime, the scientists have also gathered new knowledge about the virus itself. The 2019-nCoV genome appears to be 79 percent similar to the causative agent of the Sars epidemic 2002/2003 and 50 percent similar to the Mers viruswho, especially in the Middle East, keep jumping from camels to humans. This was the result of DNA analyzes of virus samples from the lung secretions of nine people, eight of whom visited the Huanan fish market in Wuhan shortly before Christmas.
Researchers assume that the virus has spread to humans from one of the animals that are also sold there, often only recently slaughtered. According to the analyzes, 2019-nCoV is most similar to the corona viruses that circulate in bats.
“Although our family tree analysis suggests that bats are the original hosts of these viruses, an animal sold at the Wuhan fish market could have acted as a carrier,” the researchers, who work at various Chinese specialist institutes, write in the journal “Lancet” ,
In fact, that’s very likely because the outbreak started at a time when bats are hibernating, said Guizhen Wu of the Chinese Center for Disease Control and Prevention (CCDC). In addition, no bats were sold on the market, but mammals did.
“There must be an intermediate host”
And although the similarity to bat corona viruses is 88 percent, these viruses cannot be the direct ancestors. There must be an intermediate host who has not yet been identified. “Bats were the natural reservoir for the viruses in both Sars and Mers, but another animal acted as an intermediate host,” said the researcher.
In addition, the researchers read from the virus’ genome sequence that the “spike” proteins in the virus envelope appear to be very similar to the spikes of the Sars virus from 2003. With the spikes, the viruses dock onto lung cells, specifically at a specific receptor (ACE-2) on the cell surface. Only then can they get into the cells and multiply.
The great similarity of the spikes could mean that Vaccines or medicines that have been and are being developed against Sars may also be used against 2019-nCoV – which of course needs to be tested first.
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