Deutsche Welle (English edition)
What do we know about the coronavirus?
Nearly a year has passed since COVID-19 became known worldwide. Since then, researchers have discovered much about the virus and have made progress combating it. Here are the most important points.
Almost a year ago, 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 are more than 1.5 million infections in Germany and around 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 the SARS-CoV-2 virus.
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.
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.
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 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 airconditioning 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.
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.
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.
No convincing drugs yet
Remdesivir is the only pharmaceutical drug that has been shown to shorten the course of the disease. This is why it was hotly contested on the market.
But it's 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 antiinflammatory dexamethasone , the RNA polymerase inhibitor Avigan and the malaria drug hydroxychloroquine. The efficacy and safety of the first two drugs has not yet been conclusively proven, while hydroxychloroquine has been shown to be ineffective and may even be dangerous.
How far along is vaccine development?
The first usable vaccines came on the market in the United States and EU in December. More are expected to be authorized in 2021.
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 214 vaccine projects have been launched worldwide (as of December 23, 2020) according the World Health Organization and 227 according to the German research pharmaceutical companies. These are essentially divided into three vaccine types: attenuated vaccines, inactivated vaccines and genebased RNA vaccines.
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, the latter in the US and is expecting approval in the EU in early January.
In November, AstraZeneca also reported that its vaccine candidate was far enough advanced in phase III studies to apply for Emergency Use Authorizations (EUA).
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.
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.