Where did the coronavirus come from?
The origins of the virus have been accompanied by confusion and conspiracy theories. The initial version looked as if the virus was linked to a market in Wuhan selling live animals, but a Lancet study published in January found that a third of the first patients were not directly related to that market.
Some, including US President Donald Trump, have expressed doubts about whether the virus was released after study or was even created in a Wuhan laboratory. Scientists say there is overwhelming evidence that the virus originated in the wild, and say the closest known relatives of the coronavirus are too genetically different from COVID-19 for it to leak out and subsequently trigger an outbreak.
Research has shown that the virus may have been circulating in the United States and Europe as early as December 2019, several months earlier than anticipated. Chinese state media are spreading the version that the virus may have originated outside of China.
But while Australian National University microbiology professor Peter Colignon says it is likely that the virus circulated in the United States and parts of Europe before the first cases were diagnosed in those countries, there is no conclusive evidence that the virus originated outside of China. The World Health Organization, which is investigating the origins of the virus, will examine whether COVID-19 may have been circulating in China before the first cases were detected in December.
Despite the abundance of conspiracy theories, there are a few things that most scientists agree on. Covid-19 is a coronavirus, a type of virus that causes everything from the common cold to SARS. It is a zoonotic virus, that is, originally derived from an animal. Some studies point to bats as likely carriers of coronaviruses. And most scientists still believe that the virus was transmitted to people in China, since it was there that the first cases of the disease were detected.
But it is still unknown where the virus was first transmitted to humans, and whether it was transmitted through another intermediary animal, such as a pangolin or civet, before infecting humans. “These are questions that we will never answer,” says Maureen Ferrand, assistant professor of biology at Rochester Institute of Technology. “After all, in the more than 40 years since the discovery of the Ebola virus, scientists have not been able to say with certainty which animal it is from. happened. “
Why does coronavirus affect some people more than others?
When COVID-19 was first identified, it was considered a respiratory disease. But after several months, a number of symptoms and complications of the disease became apparent.
Many people lose their sense of smell. Some people have vomiting, diarrhea, or discoloration of the fingers and toes. Some even have cognitive impairments or brain damage.
It is now known that even those recovering from COVID-19 can experience long-term consequences, including anxiety, brain damage, and chronic fatigue. A study published in the British Medical Journal in August found that about 10% of patients had long-term COVID-19 illness that lasted more than 12 weeks.
But scientists don’t know how long these effects from the coronavirus last, and they can’t really explain why some people suffer more than others.
In a material published in the journal Annals of Internal Medicine in November, two 60-year-old identical twin brothers were infected with COVID-19, and the results were very different. One of the twins was discharged from the hospital two weeks later without any complications, the other was transferred to intensive care and needed mechanical ventilation.
The case demonstrated what the researchers observed for several months: there seems to be a randomness in how severely the coronavirus affects different people – although there are some people who have a higher risk of severe illness due to existing chronic conditions or old age, among other factors.
“We all have slightly different genetics,” says Peter Colignon. “Often, for reasons we don’t fully understand, some people cope better with infections than others.”
This also applies to demography. For several months, scientists have observed trends showing that older people and men tend to be more vulnerable. Scientists know a thing or two about why children tend to have less severe infections from coronavirus – they have fewer ACE2 receptors in their nose, and thanks to these receptors, the coronavirus enters our cells. But they can’t really explain why older people have such a high death rate from coronavirus – much higher than from common flu.
“What is it about age that makes you more susceptible to disease? – asks Professor Collignon. “We have the data, and we know it’s true … but I don’t think we have all the answers to that.”
How does the coronavirus spread?
Back in January, China confirmed that the virus can spread from person to person. But after a whole year, there is still debate about how exactly this happens.
Scientists say the main way the virus spreads is through droplets that are thrown into the air when someone coughs or sneezes. These droplets fall to the ground after one to two meters, and masks can help prevent them from spreading.
But some scientists argue that the virus also spreads by aerosol, much smaller particles that can remain in the air for hours and travel long distances. This poses a problem, Collignon says: Cloth masks cannot protect against aerosol transmission.
Colignon says that while aerosol transmission can occur, it looks like most infections are caused by droplets. Instead, he believes that much more attention should be paid to the effect of indoor airflow – a recent South Korean study found that droplets of the virus can infect people more than two meters away due to airflow from an air conditioner.
There are other questions as well. So, for example, it is not clear what dose of coronavirus is needed for someone to become infected. Children may be more likely to be asymptomatic, but there are still no definitive answers about how much children are involved in the spread of the virus.
How long is someone immune to coronavirus?
In August, researchers from the University of Hong Kong said a 33-year-old man had re-infected COVID-19 – 4.5 months after the first infection.
This seemed to confirm what some people feared – that you could get infected twice.
The good news, according to Professor Colignon, is that while some people can get infected twice, “it’s such a rare event that you end up in a medical journal.” About 99% of people infected with the virus will not get infected again for at least six months after infection, Colignon said.
The big question, then, is how long does natural immunity from the virus last? Scientists cannot yet answer this question, since the virus has not been with us for a long time.
It’s the same with the vaccine – we don’t know how long the immunity to it lasts.
Scientists have suggested that the vaccine will provide some form of immunity for several years, says Peter Colignon: “But the point is, we don’t yet know.”
At the moment, coronavirus vaccines look like they are more effective than the flu vaccine that needs to be given every year.
Scientists are optimistic about the vaccine and believe that the likelihood of long-term side effects is unlikely. As Jonathan Stowe of the Francis Crick Institute in London said: “I think the risk is much greater from the virus than from the vaccine.”
But this does not mean that there are still no questions about the vaccine, other than how long the immunity lasts. We don’t know if the virus will mutate in such a way that the vaccine is ineffective. “The longer it takes us to vaccinate large populations, the more opportunities it has for mutation,” says Maureen Ferrand. And some new vaccines use mRNA technology that has never been widely used before, raising questions about whether these vaccines will remain immune over the same period of time as traditional vaccines.
When will the pandemic end?
Many around the world are pinning their hopes on the vaccine, but even that is not a quick fix. It will likely take years to vaccinate most of the world’s population – which is necessary to stop the spread – and polls indicate that some people may not want to get vaccinated. Even if people do, the vaccine is not a magic bullet.
“I think vaccines are what you need. But people seem to think that it will give me 100% protection – no vaccine will do it, ”says Professor Colignon. And even if someone is vaccinated, scientists do not yet know if it is possible that they can contract the virus and spread it, even if they themselves do not get sick.
It is likely that even after widespread vaccination, we will still have to live with the virus. After all, only one virus in human history has been declared eradicated with a vaccine – smallpox.
There are other questions that can affect how long the coronavirus has been around, such as whether the virus mutates or produces a new strain. It is possible that the virus will become less deadly or infectious, but it is also possible that the virus will become more dangerous. This possibility was highlighted by the UK’s recent announcement of a new strain of coronavirus that appears to be 70% more infectious than the old strain.
Until then, we will have to rely on a number of other measures. Jonathan Stowe of the Francis Crick Institute says this will likely mean using a number of different defenses in combination.
And here all the questions arise about how the virus spreads and how different people are affected. They are important not only for dealing with the current outbreak, but also for future outbreaks.
The problem, Colignon said, is not enough money is being spent on basic answers.
“We spend billions of dollars on vaccines and drugs, but you can’t get funding to research the basics, like how effective one mask is versus another mask,” he said.
Jonathan Stowe says he’s worried that we still haven’t found the right way to deal with the pandemic: “Here’s what worries me when we talk about future epidemics – have we learned enough lessons from this one to prevent another?”
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