COVID-19: Still no answer to these key questions till now

COVID-19: Still no answer to these key questions till now

COVID-19: Still no answer to these key questions till now. “The speed at which we are exploring new coronavirus pneumonia is unprecedented. Some pioneering works can be called miracles in the history of science.” CNN recently reported.

On December 31, 2019, the World Health Organization (WHO) was informed of “unexplained pneumonia cases”.

In less than two weeks, China confirmed and shared the genetic sequence information of the new coronavirus with the world. Three weeks later, the first batch of specific diagnostic kits came out.

In 11 months, the two COVID-19 vaccines achieved the fastest vaccine development speed in history, from creativity and clinical trials to marketing and vaccination.

As of 6:00pm on December 29, 2020, pacific time, nearly 82 million confirmed cases of new coronavirus pneumonia have been reported globally and nearly 1.8 million deaths.

CNN said that the science of viruses is too complicated, and some basic questions have not been answered. For example, how it spreads, whether it will repeat infection, and how the epidemic will end.

Maureen Ferran, an associate professor of biology at Rochester Institute of Technology in New York, USA, told CNN: “When it comes to the true nature and details, we still have a long, long way to go.” “This will allow virologists, Epidemiologists and public health departments have been busy for decades.”

On December 21, 2020, US President-elect Biden publicly received the first dose of the new coronavirus vaccine. /Reuters

Why do some people get sicker?

As an infectious respiratory disease, we have found that the accompanying symptoms of new coronavirus pneumonia are variable and complex in the past few months. Many people start to lose their sense of smell or taste; some suffer from high fever, vomiting, and diarrhea; some fingers or toes become discolored, and even cognitive function or brain damage occurs.

What confuses the scientific community is that the long-term sequelae after recovery from new coronavirus pneumonia include dyspnea, long-term fatigue, anxiety, and brain or other organ damage. “British Medical Journal” published an article in August that at least 10% of the recovered patients have sequelae symptoms. Clinically confirmed and traceable “longest” sequelae symptoms lasting more than 12 weeks.

Up to now, the scientific community has not found a reason or law that can explain the sequelae symptoms. The American Annals of Internal Medicine released a special case in November: a 60-year-old identical twin brother was infected with the new coronavirus, but the outcome was very different. One was discharged after two weeks without any sequelae symptoms. The other was transferred to the intensive care unit and required mechanical ventilation.

CNN quoted Peter Colignon, a microbiologist at the Australian National University, as saying that the only thing that can be determined now is that the children’s chance of contracting the new coronavirus and the risk of severe illness are slightly lower. In May, JAMA issued a document stating that ACE2 (Angiotensin Converting Enzyme 2) is the main channel for the new coronavirus to infect the human body. Among young children, ACE2 gene expression is the lowest (average log2 count/10,000, 2.40; 95% CI, 2.07- 2.72). Then, the expression increases with age.

“But we can’t say that this is the whole answer.” Peter Colignon added.

How does the virus spread?

As early as January, China confirmed that the COVID-19 virus would spread from person to person. A whole year later, CNN stated that the exact method of transmission is still in dispute.

Some studies have pointed out that the new coronavirus is mainly spread by respiratory droplets and contact. When an infected person coughs or sneezes, the droplets travel a meter or two in the air and then fall to the ground. Wearing a mask can effectively prevent it. There are also studies that believe that the new coronavirus may be spread through aerosols.

This is a small liquid point that is stably dispersed and suspended in the air, or it can be suspended in the air for several hours, and it will also spread to distant places with the air. “Different routes of transmission will determine epidemic prevention equipment.” Peter Colignon told CNN that if aerosols are recognized as the main route of transmission, for high-risk groups, full body protective clothing can prevent droplets, but cannot stop aerosols. , Goggles should be added.

In addition, the role of the central air-conditioning system in the spread of the virus has also been discussed. The latest South Korean study released in November showed that central air conditioning can affect indoor airflow and “help” virus droplets spread more than two meters. “These details have a great impact on public epidemic prevention policies. For example, if it is confirmed that the virus is airborne and children are susceptible, then closing schools is a reasonable prevention. On the contrary, if the virus is mainly spread through aerosols and children are not susceptible, then closing schools will It has a great negative impact, and the return is limited.” Maureen Ferran said.

In a laboratory environment, droplets from people’s cough can travel 7-8 meters. /JAMA NETWORK

Will it be transmitted from mother to child?

Research is endless, but there is no conclusion.

In March, Chinese scientists published a study in the Journal of the American Medical Association-Pediatrics, stating that pregnant women infected with COVID-19 may transmit the virus to their babies. One month later, Academician Qiao Jie, the leader of the National Medical Team of Peking University to aid Hubei, said in an interview that there were no cases of vertical transmission from mother to child. This view was supported by the June BJOG: International Journal of Obstetrics and Gynecology.

But by July, the situation changed again. “Nature-Communication” published a French study online, reporting a case of a fetus infected with the new coronavirus in the womb. According to the report, in March 2020, a 23-year-old pregnant woman with 35 weeks + 2 days of pregnancy was admitted to a hospital in Paris, France. Two days before admission, the pregnant woman developed fever, phlegm, and severe cough.

The inflammation manifested by the placenta is consistent with the maternal inflammation caused by the new coronavirus infection, showing a very high viral load. The gratifying thing is that, without antiviral drugs and other special therapies, the baby boy gradually recovered and was discharged from the hospital, “recovering health almost entirely on his own.”

In October, “Nature-Communication” published an analysis of 31 pregnant women and newborns with COVID-19 infection. Researchers have detected the new coronavirus gene in a cord blood, two full-term placenta, vaginal mucosa, and a milk specimen; two newborns were diagnosed with the new coronavirus via nasopharyngeal swabs after birth, and one of them can be attributed to congenital infection , The other can be attributed to an infection during childbirth, and both are asymptomatic. The researchers said that these data support a hypothesis: Although the probability of the spread of the COVID-19 in the uterus is very low, it is possible.

In the same month, the Journal of the American Medical Association Pediatrics re-issued an article analyzing various surveys up to that time and stated that although there are real risks, mothers infected with the COVID-19 virus follow basic infection control measures, and the chance of mother-to-child transmission is very low.

How long can immunity last?

In August, Hong Kong, China, reported the world’s first case of “secondary infection”. A 33-year-old man became asymptomatic and infected again four and a half months after the first diagnosis. “Clinical Infectious Diseases” published an article suggesting that whether through natural infection or vaccination, people may still be infected with the new coronavirus again. Judging from the current report, the secondary infection is a very unlikely event.

With the launch of the COVID-19 vaccine, the scientific community is increasingly concerned about the problem of secondary infection. “Generally, the mutation rate of coronavirus is slower than that of influenza virus. Based on this, the immune effect of vaccination should be maintained for several years.” Jonathan Stoyer of the Francis Crick Institute, the world’s leading biomedical research organization The professor said.

Maureen Ferran said that the virus is constantly mutating in its spread. The faster the vaccination of enough people is completed, or the major mutations can be delayed. “Efficiency, vaccination rate, and length of protection time are indispensable.

“At the “Lancet-Chinese Academy of Medical Sciences Conference on Medicine and Health”, Professor Roy Anderson of Imperial College London said that the higher the vaccination rate, the more extensive the immune barrier can be formed, which will help humans achieve herd immunity as a whole. If the effective rate of the new coronavirus pneumonia vaccine is 90% and the vaccination rate reaches 66.7%, herd immunity can be achieved; if the effective rate is 70%, the vaccination rate can reach 85.7%, which can be herd immunity.

But it should be noted that there are still many people who refuse to be vaccinated. According to the 51st World Lung Health Conference held on October 20, a survey of 13,426 people in 19 countries showed that 72% of the public are willing to receive the nCOVID-19 vaccine, 14% have clearly stated that they refuse to be vaccinated, and 14% are hesitant . The Brazilian polling agency “Page Data” released a survey that said the proportion of people willing to get the COVID-19 vaccine dropped from 89% in August to 73% in December.

On December 17, local time, the Supreme Court of Brazil officially authorized the federal, state, and municipal governments to enact restrictive measures against people who refuse to receive the COVID-19 vaccine, such as not allowing people who have not received the COVID-19 vaccine to enter or exit certain public places.

When will all this end?

“Vaccines are the key. But no vaccine can provide 100% protection.” Peter Colignon said. According to CNN, in the long history, the only virus that disappeared because of the vaccine was smallpox.

In addition, where the virus mutation will go is unknown. The UK found that the new coronavirus variant strain VUI-202012/01 is 70% more infectious than the old strain. “This shows that we still have to adopt a variety of methods for epidemic prevention for a long time, focusing on preventing the possibility of large-scale outbreaks.” Jonathan Stoyer said.

Peter Colignon is worried about some basic issues that have not been paid attention to. “Globally, billions of dollars are spent on vaccine and drug research and development, but the protective effect of cotton masks and N95 masks is better, and there is no in-depth study.”

“The world should learn from this pandemic to prevent and respond to the next pandemic.” CNN reported.

(source:yixuejie, reference only)

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