Part 1 Review of the Year of the Coronavirus: The Beginning of the Covid-19 Pandemic, Its Spread and the Search for Antidotes – Knowledge

0
8


Twelve months in which we got to know the virus: Never before has science learned so much about a new type of pathogen so quickly. But we still know far too little. In a three-part chronicle, we trace the progress made in knowledge about the Sars-CoV-2 and Covid-19 coronaviruses.
Here you can read the months from January to April when the pandemic began and it became increasingly clear what dangers the virus posed.

JANUARY: How 2019 gave the new 20s something bad to take with them

What will change the lives of all of humanity in 2020 will already begin in December 2019. Or possibly months before that: A coronavirus jumps from one bat to another mammal and from there to humans. To this day, no one knows who the patient is zero.

Initially, the virus probably only makes individuals sick who get well again or die without infecting another person. But at some point the pathogen adapts so well to the new host organism through random mutations in its genetic make-up that it is no longer only transmitted from animals to humans, but also from humans to humans.

That goes unnoticed for a long time. At some point, however, severe respiratory diseases accumulate in the hospitals of the 11 million city of Wuhan. Some doctors sound the alarm, including Li Wenliang.

Li Wenliang warned, was disciplined by the state, and succumbed to the virus.  imago images / ZUMA press

Enlarge

Li Wenliang warned, was disciplined by the state, and succumbed to the virus.
© imago images/ZUMA press

But the authorities dismiss him as a troublemaker and forbid him to speak. When it becomes clear he’s right, it’s too late. More and more sick people report to the clinics, the first die, later Wenliang too. On December 31 the Chinese government reports the outbreak to the World Health Organization.

A week later, Chinese researchers identified a coronavirus as the cause, on 10.1. the genetic sequence is published on a virologist website and special laboratories all over the world, above all that of coronavirus expert Christian Drosten from the Charité, are developing a test that can be used to identify the virus.

Read our other parts of the review of the year of the coronavirus:

Drosten did not react very concerned at first and did not classify the virus as more dangerous than the related Sars pathogen from 2002/2003, which was under control after a few months. But new infections with the new coronavirus are increasing so rapidly, exponentially, that the Chinese government cordoned off Wuhan on January 22nd and imposed the first lockdown of the year.

But the virus has long since traveled abroad, infected people are identified in Europe, the USA and many other regions. The WHO calls on January 30th the international health emergency, three days after a first case was registered in Germany, a 33-year-old employee of the automotive supplier Webasto. He and his family are not affected by the disease, but researchers and doctors learn a lot about the virus from the case.

The scientist of the pandemic: Charité chief virologist Christian Drosten.  Photo: imago images / Reiner Zensen

Enlarge

The scientist of the pandemic: Charité chief virologist Christian Drosten.
© imago images / Reiner Zensen

FEBRUARY: Infectious before you feel sick

There is great ignorance about the novel virus at the beginning of the pandemic. One of the most important questions: how and when is the virus transmitted? In February, the reconstruction of the first Sars-CoV-2 infections in Germany provides some clues. On January 20, an employee of the car accessories manufacturer Webasto flies from the Shanghai branch for a meeting in Munich.

She, “patient zero”, initially considers fatigue, chest and back pain to be jet lag symptoms, but goes back to China on the 25th to see a doctor because she now also has a fever. The infection is diagnosed on the 26th and Webasto notified on the 27th. The Munich health department immediately determined the employee’s contacts and identified a total of 16 infections.

[Wenn Sie alle aktuellen Entwicklungen zur Coronavirus-Pandemie live auf Ihr Handy haben wollen, empfehlen wir Ihnen unsere App, die Sie hier für Apple- und Android-Geräte herunterladen können]

Patient one is infected in the meeting when he sits next to patient zero. The two colleagues sitting opposite are spared. Another employee is infected when he fetches the salt from the table in the canteen where patient zero is sitting.

The research team headed by Merle Böhmer from the Bavarian State Office for Health and Food Safety, Udo Buchholz from the Robert Koch Institute (RKI) and Victor Corman from the Charité concludes that the risk of infection is “considerable” before the onset of symptoms or shortly afterwards. In at least one, possibly even five cases in the Munich case group, an infected person passed on Sars-CoV-2 before symptoms occurred. In at least four cases, the infected were just noticing their first symptoms when they were also infecting others.

“The high viral load in the throat right at the beginning of the symptoms suggests that sick people are infectious very early, possibly even before they even notice that they are sick,” says the director of the Bundeswehr Institute for Microbiology involved in the study, Roman Wölfel.

It is now clear: about one to two days before the first symptoms of the disease appear, infected people are already infectious and remain so for the first few days with symptoms. Later seriously ill people seem to be more infectious than infected people who only become slightly ill. However, whether infected people who develop no symptoms at all, i.e. who remain “asymptomatic”, can pass the virus on is controversial – also because studies often do not check whether someone remains asymptomatic or whether someone still develops symptoms. The RKI assigns a “subordinate role” to the transmission of asymptomatically infected people.

MARCH: The invisible danger

On March 9th, the members of the Berlin Cathedral Choir meet for a weekly rehearsal. There is plenty of space on a good 120 square meters, and there is space between the participants. But in the end 60 of the 80 singers are infected with Sars-CoV-2.

It is situations like this that make virologists and epidemiologists sit up and take notice that the virus is not only transmitted through droplet and smear infections, but also through aerosols. When speaking or singing loudly, aerosols have an easy time – in poorly ventilated rooms. Family celebrations and sporting events become superspreading events, at which an infected person infects many more people.

In March, the evidence increased: the infected person, who sat in the canteen with his back to the sick person, the family from Wuhan, who became infected in a restaurant from many meters away. In early summer, laboratory experiments deliver results: the viruses can transmit not only small, barely visible droplets, but also the much smaller aerosol particles.

An electron microscope (colored) image shows the novel coronavirus Sars-CoV-2, which emerges from cells cultivated in the laboratory.  Photo: dpa

Enlarge

An electron microscope (colored) image shows the novel coronavirus Sars-CoV-2, which emerges from cells cultivated in the laboratory.
© dpa

The droplets are between five and 500 thousandths of a millimeter in diameter, aerosols are between 0.01 and five thousandths of a millimeter in size. They are so light that they can float for several hours without moving air. Aerosols can be contagious if the person they came from is no longer in the room. What makes aerosols dangerous is that when inhaled they can get deep into the lungs, even right into the alveoli. There the coronavirus finds docking points en masse to set an infection in motion.

In summer, the transmission route via aerosols plays a lesser role. People stay outside more often, where the wind quickly carries them away and heat and sun attack the viruses. Only in the cold season of the year do aerosols gain importance again as carriers. FFP-2 masks offer a certain protection against the invisible virus clouds. And of course: ventilation!

APRIL: The search for drugs

Remdesivir is the first drug to receive provisional approval in the US (May 1) and conditional approval in Europe (July 3) for the treatment of Covid-19, the disease caused by Sars-CoV-2. Its benefit for patients has not been proven. The largest study to date even shows that it is of no use.

The drug was originally developed against the Ebola virus by the pharmaceutical company Gilead. But it should also work against other viruses such as the Marburg virus and Mers and Sars viruses, which are closely related to Sars-CoV-2.

The active ingredient is similar to adenosine nucleotides, a type of building block from which the genetic material of new viruses is put together in infected cells.

Interactive map

If an active ingredient molecule is built in, it blocks or slows down the enzyme that joins the new strands of virus genome, in animal experiments also that of Sars-CoV-2.

In January, the New England Journal of Medicine (NEJM) reported the treatment of the first confirmed case in the United States. The 35-year-old man develops pneumonia. His condition improved just one day after starting treatment with Remdesivir.

At the end of April, US government advisor Anthony Fauci reported positive interim results from a clinical trial. Remdesivir shortens the time to recovery from 15 to about ten days. The effect is “clear and statistically significant,” reports Fauci to the US President.

But a study published at the same time in the journal “Lancet” does not confirm these results. Remdesivir has no clinically meaningful positive effect, reports a Chinese research team. The amount of virus detected in the patients after five days of treatment was also largely the same as that in patients who had received an ineffective placebo. Two other studies, co-funded by Gilead, produce mixed results.

The drug, for which Gilead estimates around 2000 euros per patient treated, is still being approved.

A study by the WHO should bring clarity. With over 400 participating hospitals in 30 countries, the Solidarity Study is much larger than any previous one. It shows that remdesivir is just as ineffective as three other drugs: the malaria drug hydroxychloroquine, the HIV drug lopinavir and an antiviral hormone from the group of interferons. Mortality, the need for artificial ventilation, and the length of stay in hospital remain the same with or without medication. Gilead questions the validity of the study.

The WHO is meanwhile looking for active ingredients, so far no agent against Sars-CoV-2 has been found. But there are newer antiviral agents, drugs that affect the immune system, and artificially produced antibodies that should be evaluated.

The only bright spot so far is the anti-inflammatory drug dexamethasone. The inexpensive and globally available active ingredient reduces mortality among ventilated Covid-19 patients and in patients who are administered oxygen.

It continues here with part 2: Children in the infection process – and explosive spread events



Source link
https://m.tagesspiegel.de/wissen/teil-1-rueckblick-auf-das-jahr-des-coronavirus-der-anfang-der-covid-19-pandemie-ihre-verbreitung-und-die-suche-nach-gegenmitteln/26754210.html

LEAVE A REPLY

Please enter your comment!
Please enter your name here