The coronavirus may have originated from bats, but it is likely that another species has infected humans.
When the Covid-19 epidemic broke out in January, many researchers investigated the intermediate host for transmitting coronavirus to humans. On Feb 15, Wu Yuan Bin, head of the Department of Science and Technology for Social Development, China’s Ministry of Science and Technology, said the studies identified bats as the most likely species.
However, recently published findings suggest that pangolin may be a host for the virus from bat to human. In other words, the SARS-CoV-2 virus was present in the first bat, but through an intermediate host, pangolin was transmitted to humans.
Mysterious intermediate host
In an article in Conversation , the team at the University of Michigan says they have evidence to show that pangolin is an intermediate host. The researchers agree with the general opinion that SARS-CoV-2 virus first appeared in Chinese horseshoe bats. However, the possibility of direct transmission from this bat to humans is quite low.
In 2003, the SARS virus was also transmitted from bats to an intermediate host, the mongoose, before it was transmitted to humans. Another coronavirus, MERS-CoV, caused the MERS epidemic in 2012 and also spreads from bats to camels before spreading it to humans.
It is important to identify the intermediate host, knowing which species will help to limit sales, thereby reducing the likelihood of spreading the virus. Since the end of January, a team of Chinese researchers said the snake, including the Chinese scorpion and cobra, could be the direct host of the SARS-CoV-2 virus to humans.
However, this study is suspected because there has been no evidence that coronavirus can be transmitted from cold-blooded animals such as snakes to humans.
Conclusions on snakes are based on the assumption that the codons (the trio of transcription codes, the genetic code on the information RNA) of the virus and host spread must be identical. After comparing the genetic codes of eight animals at the Wuhan Seafood Market, the team determined that snakes are the most similar genetic code to SARS-CoV-2.
However, the hypothesis of the above study has never been proven. The University of Michigan team compared the genetic code of the three coronavirus strains to about 10,000 animals, and found that the virus codon did not necessarily match the actual host.
The evidence shows that pangolin is the host
The group then went on to conduct a study on Malaysian pangolin (Manis javanica). They found that the genetic code taken from the coronavirus attached to the lung cells of this pangolin was 91% similar to SARS-CoV-2.
The protein spikes of these two viruses have only 5 distinct amino acids. Compared to the coronavirus from bat species, the protein spines of SARS-CoV-2 virus have 19 distinct amino acids. From this evidence, the team believes that pangolin is an animal most likely to spread the SARS-CoV-2 virus to humans.
This is not the first scientific study to conclude that the Malaysian pangolin. At the end of March, another research team at the University of Hong Kong also found a virus directly related to the SARS-CoV-2 virus in the Malaysian pangolin, seized from a wildlife transport line illegal in southern China.
“Detecting similarities of some strains of pangolin with SARS-CoV-2 virus suggests that the animal may be listed as an infectious host and need to be removed from animal markets. wild “, Dr. Tommy Lam, study author concludes in scientific report.
“Although pangolin is the most suspect species, our study concludes that we still need to consider other types of intermediate hosts. The coronavirus can be transmitted through many intermediate hosts before it is transmitted to humans. .
Several studies indicate that ferrets and cats can also be infected with SARS-CoV-2. We still don’t know if humans are likely to catch coronavirus from these animals, “a University of Michigan research team concluded.
- WHO updates mask recommendations
Now they are advised to wear not only sick.
WHO Director-General Tedros Hebreyusus, at a new briefing on COVID-19, announced new recommendations for the prevention of coronavirus. Here are the main points:
- Doctors and other medical staff should always wear masks, regardless of whether they work with infected coronavirus infections or not.
- People over 60 years of age, as well as those who have chronic diseases, are advised to wear masks wherever it is impossible to maintain physical distance.
- The governments of the countries should encourage the wearing of masks in any places where it is impossible to maintain physical distance, especially for public transport and shops.
- Those with symptoms similar to coronavirus infection should stay at home. All who contacted him should be quarantined.
- If a sick person or someone who has contacted him needs to leave the house, he must wear a mask.
- WHO considers masks to be of high quality, which consist of three layers of different materials or more.
Previously, the WHO spoke only about the need to wear masks for patients who were ill, because there was insufficient data (apart from clinical studies, which many experts consider to be of little relevance to real life).
- WHO recorded 106,000 new infections globally in 24 hours
The WHO recorded 106,000 infections in 24 hours, a record day since the outbreak, with two-thirds of these cases recorded in only 4 countries.
Tedros Adhanom-Ghebreyesus, Director General of the World Health Organization (WHO), said on May 20 that the number of coronavirus infections reported to the agency in the past 24 hours has been higher than at any time since outbreaks, according to CNN.
“We still have a long way to go in this pandemic,” Tedros said at a news conference in Geneva, Switzerland. “In the past 24 hours, 106,000 cases have been reported to WHO – the highest daily level since the outbreak.”
“About two-thirds of these cases have been reported in only four countries,” he added.
According to WHO epidemiologist Maria Van Kerkhove, confirming with CNN via email, these four countries are the US , Russia, Brazil and India.
It should be noted that there may be a delay in reporting the number of cases at various points in the process, so the above date record does not mean that these 106,000 people were infected, tested or statistically counted in the last 24 hours.
According to the constantly updated data of John Hopkins University, the world has recorded nearly 5 million cases of coronavirus, of which more than 326,000 people have died. The United States remains the leading country in both cases – more than 1.5 million, and deaths – more than 93,000.
Notably, Russia has recently become the second country in the number of cases – more than 308,000, although only a few weeks earlier did not even make the top 20 of the list. Brazil also climbed rapidly in the ranking, ranking third in the number of cases – more than 271,000.
Russia is ranked second in terms of deaths – more than 35,000, followed by Italy – more than 32,000, France – more than 28,000, Spain – more than 27,000.