What can be learned from other coronaviruses about the characteristics of the mysterious new coronavirus?
For new coronavirus infectious disease (COVID-19), development of vaccines and silver bullets is urgent, but it is general view that vaccine development will not be in time for the first wave of the epidemic occurring as of April 2020 . The new coronavirus (SARS-CoV-2) has many unknowns at the research stage, but when there are many points to learn from other
What Can Other Coronaviruses Tell Us About SARS-CoV-2? | Quanta Magazine
https://www.quantamagazine.org/what-can-other-coronaviruses-tell-us-about-sars-cov-2-20200429/
SARS-CoV-2 is a coronavirus that causes diseases in mammals and birds. Up to now, dozens of coronaviruses that infect domestic animals and wild animals have been confirmed, but the virus strains that infect humans and cause a common cold are 'HCoV-OC43', 'HCoV-229E', and 'HCoV'. -NL63 'and' HCoV-HKU1 '. HCoV is an abbreviation for 'human coronavirus'. The SARS epidemic in 2003 and the MERS epidemic in 2012 are coronaviruses that cause more serious symptoms.
Much of SARS-CoV-2 is in the research stage and should not be over-estimated, but it can be learned from the history of other coronaviruses. For example, MERS and SARS coronaviruses do not appear to spread before symptoms appear, but SARS-CoV-2 is believed to be highly infectious prior to onset. It is believed that this is because MERS coronavirus and SARS coronavirus grow in the lower respiratory tract , whereas SARS-CoV-2 grows in the upper respiratory tract.
The infectivity of the new coronavirus was found to be `` strongest before the onset '', and half of the infected people may have the virus transmitted from pre-onset people-GIGAZINE
◆ Does COVID-19 cause gastrointestinal symptoms?
COVID-19 is commonly associated with fever, malaise, and cough, but gastrointestinal symptoms such as diarrhea and vomiting have also been reported. In this regard, Smith pointed out that gastrointestinal symptoms were also reported during the 2003 outbreak of SARS. Gastrointestinal symptom is also a major symptom in porcine epidemic diarrhea virus (PEDV), and is also seen in coronavirus that infects cattle, dogs and cats. The susceptibility of each organ to the virus is not yet clear, but Smith thinks that gastrointestinal symptoms should be considered as one of the symptoms of COVID-19.
◆ Does the loss of taste occur in other coronavirus infections?
Many people with COVID-19 infections have reported loss of taste and smell. Some studies have shown that SARS-CoV-2 targets tissues of the central nervous system, which may lead to loss of taste and smell, leading to more serious consequences, including neuropathy. It is also seen.
Why does new coronavirus infection become severe in only some people? -GIGAZINE
Studies of SARS and other coronaviruses have shown in animal studies that the virus can enter the brain through the olfactory bulb, which is involved in taste information processing. As of April 2020, it has been pointed out that COVID-19 has an effect on the brain.
The possibility that the new coronavirus will affect the brain-GIGAZINE
Also, if the virus acts on taste neurons, the infection may cause other neurological disorders even after recovery from an acute infection. Results from a 2000 study show that many patients with neurological disorders, including multiple sclerosis, are more likely to have HCoV-OC43 in their brain than healthy people.
◆ What is needed to stop the fashion
A vaccine is needed to end an infectious disease, but it takes years to develop a vaccine. For this reason, it is necessary to consider possibilities other than vaccines. For example, PEDV has an effective vaccine at the time of writing, but for a long time farmers needed to fight the epidemic of infectious diseases by means other than vaccines. The 'self-vaccine' was used as a solution.
During the PEDV epidemic, farmers and veterinarians took samples of PEDV from the intestines of pigs that had fallen ill with the infection and transferred this intestinal tissue to another sow with immunity to the virus. Pigs transplanted with tissue can get sick, but the symptoms are relatively mild. Antibodies made in the body of these sows are given to piglets through the placenta and breastfeeding, which will lead to infection protection.
Of course, this method is not directly applicable to humans, but in a sense it is close to the strategy adopted by Sweden. Without providing strict action limited in Sweden, the risk of severe low people the way that to win the herd immunity by infection freely to move the virus is taking .
◆ Does exposure to the virus affect severity?
Many health workers, despite being young and healthy, have severe symptoms of COVID-19. In experiments porcine respiratory coronavirus (PRCV), porcine ingesting isolates PRCV from the trachea to be severe than pigs became ill spontaneously are shown , greater the amount of virus that infects The more likely it is that you will lose control over the replication and spread of the virus.
◆ Is it possible to be infected twice with COVID-19?
The HCoV-229E was ingested into the subject (PDF file) experiment in, the antibody response of a subject with the passage of time shows a sharp decline, many of the subjects were shown to be infected with the same virus after one year. Also regarding SARS, it has been found that the antibody response of patients decreases over time.
In addition, it has been confirmed that the virus continues to be transmitted continuously in some animals such as cats. In the case of cats, the infection will continue for several months. During this time, the virus mutates, starting with a relatively mild gastrointestinal upset and eventually developing into severe conjunctivitis. Such cat coronaviruses are said to have a very high mortality rate.
At the time of writing, no evidence was found that SARS-CoV-2 causes a specific mutation. On the other hand, although there is a possibility of false negatives, it has been reported that a person who once showed a negative reaction showed a positive reaction again.
◆ Will SARS-CoV-2 become endemic ?
If a vaccine is developed, the evolutionary potential of the virus may be limited, but if it is not contained, humanity may continue to experience the COVID-19 epidemic over and over again. There is.
During this process, the symptoms may be relatively mild. It is said that it became difficult to aggravate the host while HCoV-OC43 was mutated. PRCV also changed from a pathogen that causes a fatal intestinal disorder by mutation to a mild respiratory pathogen. It is possible that such mutations occur in SARS-CoV-2.
On the other hand, the new strain of canine coronavirus identified in 2017 is considered to be a combination of existing dog coronavirus and bovine coronavirus, and SARS-CoV-2 is combined with other coronaviruses. There is also a possibility. However, it is impossible for humans to predict such events, and there is no choice but to continue monitoring the virus so that the next epidemic can be dealt with.
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