One year on: What have we learned since news of COVID-19 first broke? | Science| In-depth reporting on science and technology | DW | 30.12.2020
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One year on: What have we learned since news of COVID-19 first broke?

A year ago, ophthalmologist Li Wenliang was the first to share information about a SARS-type lung infection with colleagues in Wuhan, China. Researchers have learned a lot since then. Here are the most important points.

This image from video, shows a selfie of Dr. Li Wenliang. The Chinese doctor who got in trouble with authorities in the communist country for sounding an early warning about the coronavirus outbreak died Friday, Feb. 7, 2020, after coming down with the illness.

Li Wenliang, who gave an early warning on the coronavirus outbreak, later died of COVID-19

Ophthalmologist Li Wenliang,  who worked at the Wuhan Central Hospital, was the first to share information about suspected SARS-type lung infections in the city in Central China on December 30, 2019.

He distributed the news on the social media platform WeChat to colleagues at different hospitals in the city. Police then admonished him for "making false comments on the internet" but an official inquiry later exonerated him. 

Li Wenliang died from COVID-19 on February 2. 

A novel coronavirus recognized

At the beginning of the second week of January 2020, Chinese authorities made the first public announcement that a new type of virus was rampant in the city of Wuhan. 

Now, at the end of December, there have been more than 1.5 million infections in Germany and more than 80 million worldwide. 

Here's an overview of what has been discovered about the virus to date, and how far medicine has progressed in the fight against SARS-CoV-2, the novel coronavirus.

Origin of the virus

When the existence of the virus was announced, the first infection of a human by a vertebrate animal had apparently already occurred several weeks earlier.

Initially, Chinese authorities seemed to have tried to suppress any evidence. To this day, it's not exactly clear when and where the virus jumped from animal to human hosts. Transmission from a bat to an intermediate host, perhaps a tanuki — otherwise known as an Asian raccoon dog — and then to humans is considered the likely origin of the pandemic that is still in full swing today. 

There is evidence to suggest that the virus had already spread worldwide in late summer 2019. It has since been found in samples taken in Italy in September of that year, which is consistent with an analysis of SARS-CoV genomes by British researchers.

Coronaviruses under the electron microscope

One of the first images of the novel coronavirus was taken in January 2020

Decoding the virus

Chinese virologists deciphered the genetic information of the virus in record time. On January 21, they published the genome structure, and three days later they released a detailed description of the virus. This enabled physicians and microbiologists worldwide to begin developing drugs and vaccines.

A typical feature of the virus is the spike proteins (ACE-2) located on its surface. These are crucial for binding to the host cell. That is why a large part of drug and vaccine development has been focused on binding or blocking this protein, or rendering it ineffective in some other way. 

Illustration of a coronavirus

A model of the coronavirus: Most prominent is the spike protein (S) that gives the virus its crown-like appearance

Transmission

In the meantime, a study carried out by virologists in the city of Heinsberg, one of the first hotbeds of the disease in Germany, has established that the virus is particularly prevalent in the throat and lungs. The greatest danger of infection — besides by coming into direct contact with an infected person or touching a contaminated surface, known as smear infections — is through aerosol transmission. The virus can spread particularly well through air-conditioning systems, such as those used widely in the meat industry. 

Closed rooms with many people in them are very dangerous. That's why lockdown measures, the closure of entertainment establishments and the cancellation of trade fairs and major events were very effective in containing the disease. 

Watch video 03:23

Does air conditioning help spread COVID?

The largest chains of infection could be traced back to so-called superspreader events. 

The use of mouth-and-nose protection, i.e., face masks,has now become established in almost all countries of the world. However, many medical professionals initially questioned whether most people were capable of using masks in everyday life in such a way as to help prevent potential virus transmission.

What is most important is for people to wash their hands, keep their distance from others and air rooms thoroughly.

Even if some pets, such as cats, ferrets and golden hamsters, can become infected by humans, they have not been found to play a significant role in infection chains. However, infections in mink farms in numerous countries have caused great concerns among veterinary doctors. Authorities have subsequently ordered the culling of millions of animals.

Symptoms and risk groups

Initially, it was thought that the new virus was no more dangerous than the seasonal flu. Now, however, physicians know better: The disease poses a threat similar to that of the devastating Spanish flu of 1918. Although many people can get a SARS-CoV-2 infection without symptoms, others become very ill with COVID-19, the disease caused by the virus.

Watch video 01:44

93-year-old man recovers from COVID

Some groups of people are more often affected than others: People with previous illnesses, elderly people, people with blood type A and men are more at risk.

Pathologists who have examined COVID-19 victims have been able to confirm that high blood pressure, diabetes, cancer, kidney failure, liver cirrhosis, asthma and cardiovascular diseases are among the most dangerous preexisting conditions. In principle, however, a severe case of the disease can affect anybody, including young people. 

Course of the disease

Mild forms of COVID-19 can present like a cold. Typical symptoms are a sore throat, breathing problems and a loss of sense of smell and taste.

In severe cases, however, a life-threatening multi-organ disease can occur.

This often leads to sepsis — a frequently fatal overreaction of the immune system that attacks the infected person's own tissue and organs.

The severity of the disease depends, to a large extent, on how strongly a person's immune system reacts to the pathogen. 

Treatment

At the beginning of the pandemic, many patients with severe courses of the disease received artificial respiration (intubation) at an early stage and died all the same.

Now, however, physicians working in intensive care units have moved away from standard ventilation, because lung specialists have stressed that artificial respiration under positive pressure can do more damage than good to the lungs.

As long as patients are able to breathe on their own, they now receive oxygen without being connected to a respirator. Intubation is used as an option only in an extreme emergency.

In many cases, when the kidneys are severely damaged by COVID-19, dialysis is also necessary. Intensive care units are now also taking other damaged organs into account.

The healing process can be accelerated in specialized clinics by the administration of antibodies from the blood of cured COVID-19 patients. These antibodies take up the fight against the virus in the body of the patient who receives the donated blood.

As a rule, COVID-19 patients must undergo lengthy, individually tailored rehabilitation measures after their medical treatment. These must also take into account their specific previous illnesses and possible organ damage.

Watch video 03:16

What is remdesivir?

No convincing drugs yet

Remdesivir is one of the few pharmaceutical drugs that have been shown to shorten the course of the disease. This is why it was hotly contested on the market. 

But it is not a miracle cure. It shortens the healing process by a few days in patients who receive oxygen, but it does not improve their chances of survival. Meanwhile, the World Health Organization has advised against remdesivir for hospitalized COVID-19 patients. 

Doctors are also trying to use other drugs that are already on the market to combat the coronavirus. These include the anti-inflammatory dexamethasone,   which has been approved in Great Britain  after a trial showed the drug to reduce the risk of death in hospitalised patients who require oxygen by about one third. 

Others include the RNA polymerase inhibitor Avigan and the malaria drug hydroxychloroquine

The efficacy and safety of the first has not yet been conclusively proven, while hydroxychloroquine has been shown to be ineffective and may even be dangerous. 

On December 18, 2020 the WHO stated,  that "corticosteroids (such as dexamethasone) are the only class of medicines to demonstrate some benefits", adding that "for patients with mild or moderate disease, finding effective, safe, affordable and accessible therapeutics to reduce mortality and morbidity remains an urgent priority."

How far along is vaccine development?

The first usable vaccines came on the market in Great Britain, the United States and EU in December. More are expected to be authorized in 2021. 

Russia and China  have also authorized vaccines, respectively. Both countries are also exporting those into numerous third countries. 

Mass production and launching effective vaccination campaigns is the main challenge for the pharmaceutical industry and health authorities. Gene-based RNA vaccines, which can be produced relatively quickly, have an advantage here. 

However, experts are expecting that vaccination campaigns are unlikely to finish before 2022. 

More in the pipeline 

At least 233 vaccine projects have been launched worldwide (as of December 22, 2020) according the World Health Organization and 246 according to the German research pharmaceutical companies. These are essentially divided into three vaccine types: attenuated vaccines, inactivated vaccines and gene-based RNA vaccines. 

Watch video 02:30

Vaccine efforts a mix of competition and cooperation

 

In the latter case, however, physicians have been entering uncharted territory because no such approved vaccines have been available in the past. Both the BioNTech-Pfizer and the Moderna vaccines are such RNA vaccines. The former has approval in both the EU and US, while the latter has so far been approved only in the US and is expecting approval in the EU in early January. 

And on December 30, British regulators approved the AstraZeneca vaccine  designed by scientists at the University of Oxford. It is not an mRNA vaccine, but an attenuated vector vaccine, in which a harmless chimpanzee cold-virus serves to transport parts of SARS-CoV-2 proteins, that trigger an immune response. 

In addition, there is a tuberculosis vaccine that has already been approved. This does not directly target SARS-CoV-2 but strengthens basic innate immunity. Researchers at the Max Planck Institute for Infection Biology in Berlin are currently trying to improve this vaccine genetically. 

DW offers a COVID-19 vaccine tracker,  to keep you up-to-date

When does herd immunity occur?

It's true that more and more people are becoming infected worldwide. By the end of December, more than 80 million people will have contracted the virus. However, with a population of 7.8 billion, the world is still a long way from achieving any effective degree of immunity to the disease.

In addition, it's unclear whether recovered patients remain permanently immune to the virus. A serological blood test can determine whether someone is carrying antibodies against the virus. A polymerase chain reaction (PCR) test taken with a cotton swab can make it clear whether someone is acutely ill and contagious. 

This article has been updated since its original publication. 

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