What is still unknown about Covid-19 after a year

What is still unknown about Covid-19 after a year

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The speed with which we learn about the coronavirus is unprecedented and scientists say that we already know a remarkable amount.

But a year later, with more than 81 million infections reported and 1.7 million deaths around the world, there’s still a lot we don’t know about Covid-19.

These unknowns range from the basics – like the onset of the virus – to the most complicated questions, including how will this pandemic end?

“We learned a lot, but in terms of understanding anything in any real detail, we have miles and miles ahead of us,” said Maureen Ferran, associate professor of biology at the Rochester Institute of Technology. “This will keep virologists and public health officials busy for decades.”

Where the coronavirus originated

As governments rushed to find a vaccine for the virus, one of the most basic questions escaped the public’s radar: what is the origin of the virus?

The origin of the virus was pursued by confusion and conspiracy theories. Initially, the virus appeared to be connected to a Wuhan market that sold live animals, but a Lancet study published in January found that a third of the initial patients had no direct connection to that market.
Some, including U.S. President Donald Trump, questioned whether the virus had been released after being studied or created in a Wuhan laboratory. Scientists say there is overwhelming evidence that the virus originated in nature, and say that the closest known relatives of the coronavirus are genetically different from Covid-19 so that it has leaked and subsequently caused the outbreak.
Studies have found evidence that the virus may have circulated in the United States and Europe in December 2019, months earlier than previously thought. Chinese state media released the narrative that the virus may have originated outside China.

But although Peter Collignon, professor of microbiology at Australian National University, says the virus is very likely to have already circulated in the United States and parts of Europe before the first cases in those countries have been diagnosed, there is nothing conclusive to show that the virus originated outside China. The World Health Organization, which is investigating the origin of the virus, will investigate whether Covid-19 could be circulating in China before the first cases were identified in December.

Despite the abundance of conspiracy theories, there are some things that most scientists agree with. Covid-19 is a coronavirus, a type of virus responsible for everything from the common cold to SARS. It is zoonotic, which means that it originally came from an animal. Some studies point to bats as the probable vectors, which are known to carry coronavirus. And most scientists still think the virus was transferred to humans in China, since it was there that the first cases were identified.

But we still don’t know where the virus first passed to humans and whether it was transferred by another animal intermediary, such as a pangolin or a civet cat, before infecting humans. These are questions that we may never answer, says Ferran – after all, in the more than 40 years since the discovery of Ebola, scientists have been unable to say with certainty which animal it came from.

Why it affects some people more than others

When Covid-19 was first identified, it was considered a respiratory disease. But over the months, a number of symptoms and complications of the disease became apparent.

Many people lose their sense of smell. Some people vomit or have diarrhea, or discoloration of the fingers or toes. Some even have impaired cognition or brain damage.
We now know that even those who recover from Covid-19 can experience lasting effects, including anxiety, brain damage and chronic fatigue. A study published in the British Medical Journal in August found that about 10% of patients had a prolonged Covid-19 disease lasting more than 12 weeks.
But scientists don’t know how long these effects of Covid-19 last – and they can’t explain why some people suffer more than others.

A letter published in the Annals of Internal Medicine in November described a case in which two identical 60-year-old twin brothers were infected with Covid-19 and had very different results. One of the twins was discharged after two weeks without complications, the other was transferred to intensive care and required a ventilator.

The case demonstrated what the researchers have been observing for months: there seems almost to be a randomness in how the coronavirus severely affects different people – although there are some people who are at a higher risk of serious illness due to existing chronic conditions or old age, among others factors.

“We all have a slightly different genetics,” said Collignon. “Often, for reasons we don’t fully understand, some people handle infections better than others.”

This is also true for demographic data. For months, scientists have observed trends showing that older people and men tend to be more vulnerable. Scientists know something about why children tend to have less severe coronavirus infections – they have fewer ACE2 receptors in their noses, and these receptors are how the coronavirus enters our cells. But they cannot explain why the elderly have such a high mortality rate from coronavirus – much higher than that of the common flu.

“What is it about age that makes you much more susceptible to disease?” Collignon questioned. “We have the data and we know it is true … but I don’t think we have all the answers to that.”

How the coronavirus spreads

In January, China confirmed that the virus could spread from person to person. But a full year later, there is still debate about exactly how it happens.

Scientists say the main way the virus spreads is through droplets that are sent into the air when someone coughs or sneezes. These drops fall to the ground after a meter or two and masks can help prevent them from spreading.

But some scientists argue that the virus is also being spread by aerosols – much smaller particles that can be suspended in the air for hours and travel long distances. That would be a problem, says Collignon – fabric masks cannot protect against aerosol transmission.

Collignon says that although aerosol transmission may be happening, it appears that most infections are caused by droplets. Instead, he thinks that much more focus needs to be put on the effect of airflow indoors – a recent South Korean study found that droplets of viruses can still infect people more than two meters away due to airflow. of an air conditioning unit.

There are other issues as well. According to Ferran, it is not clear what dose of coronavirus is needed for someone to be 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.

All of these issues are important, as they have implications for policy approaches adopted by governments. If children are involved in the spread of the virus, it makes sense to close schools – and conversely, if they are not involved in the spread of the virus, closing schools can have a big impact with limited payoff.

How long is someone immune

In August, researchers at the University of Hong Kong said a 33-year-old man was reinfected with Covid-19 – 4.5 months after the first infection.

This seemed to confirm what some people feared – that it was possible to become infected twice.

The good news, according to Collignon, is that while some people can be infected twice, “it is such a rare event that you get published in a medical journal.” About 99% of people infected with the virus do not appear to be infected again for at least six months after infection, said Collignon.

The big question, then, is how long does natural immunity against the virus last? Scientists cannot answer that yet, because the virus has not been with us long enough.

The same is true for the vaccine – we don’t know how long immunity lasts for it.

Scientists assumed the vaccine would provide some form of immunity for several years, said Collignon. “But the main point is that we don’t know yet.”

At the moment, coronavirus vaccines appear to be more effective than the flu vaccine, which needs to be administered every year.

Scientists are optimistic about the vaccine and believe that the chance of long-term side effects is unlikely. As Jonathan Stoye of the Francis Crick Institute in London says, “I think the risk is much greater with the virus than with the vaccine.”

But that does not mean that there is still no doubt about the vaccine beyond how long immunity lasts. We don’t know if the virus will mutate, in a way that will make the vaccine ineffective. The longer it takes to vaccinate large sections of the population, the more opportunities it will have to mutate, Ferran said. And some of the new vaccines employ mRNA technology, which has never been widely used before – raising questions about whether the immunity from these vaccines will last as long as traditional vaccines.

When the pandemic is over

All of these questions have implications for the big question: when will it all end?

Many around the world are pinning their hopes on the vaccine, but even that is not a quick fix. It will probably take years to vaccinate the majority of the world’s population – something that would be needed to prevent it from spreading – and research shows that some people may not want to be vaccinated. Even if people do, the vaccine is not a silver bullet.

“I think vaccines are the way to go. But people seem to have a vision that it will give me 100% protection – no vaccine does that, ”said Collignon. And even if someone gets vaccinated, scientists still don’t know if it is possible for them to contract the virus and spread it, even if they themselves don’t get sick.

It is likely that, even after a widespread vaccination, we still have to live with the virus. After all, only one virus in human history has been declared eradicated by a vaccine – smallpox.

There are other issues that can influence how long the coronavirus stays with us, such as whether the virus mutates or develops a new strain. It is possible for the virus to become less deadly or infectious – but it is also possible for the virus to become more virulent. This possibility was highlighted by the UK’s recent announcement that it identified a new strain of coronavirus that appears to be 70% more infectious than the old strain.

In the meantime, we will need to rely on a number of other measures. Stoye, of the Francis Crick Institute, said that this would probably mean taking a number of different protections combined. “You cannot say – we will do one thing and you will prevent the virus from spreading.”

And that’s where all the questions about how the virus spreads and how different people are affected come in. These are important not only for dealing with the current outbreak – but for future outbreaks.

The problem, says Collignon, is that not enough money is spent to answer the basics.

“We spend billions of dollars on vaccines and drugs, but you can’t get funding to do basic research like the effectiveness of this mask compared to that mask,” he said, adding that partly because the answers to those questions didn’t make the problem go away – they just decreased the risk.

Stoye said he was concerned that we still haven’t found the right way to deal with the pandemic.

“That’s what worries me when we talk about future epidemics – have we learned enough from this one to prevent another one?”

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