5 things we know and don’t know about the Corona virus, 5 years after its appearance
Five years ago, a group of people in the Chinese city of Wuhan were infected with a virus unprecedented in the world.
The germ had no name, nor the disease it might cause. It ended up sparking a pandemic that exposed deep inequalities in the global health system and reshaped public opinion about how to control deadly emerging viruses.
The virus is still among us, even though humanity has developed immunity through vaccinations and infection. It is less deadly than in the early days of the pandemic and no longer tops the list of leading causes of death. But the virus is evolving, which means scientists must follow it closely.
Where did the SARS-CoV-2 virus come from?
We don’t know. Scientists believe the most likely scenario is it spreading in bats, like many coronaviruses. They believe it then infected another species, perhaps raccoon dogs, civet cats or bamboo rats, which in turn infected humans handling or butchering those animals at a market in Wuhan, where the virus first emerged. Human cases emerged in late November 2019.
This is a known path of transmission, and likely led to the first epidemic of a similar virus, known as SARS. But this theory has not been proven for the virus that causes Covid-19. Wuhan is home to several research laboratories involved in collecting and studying coronaviruses, sparking controversy over whether the virus leaked from one of the labs.
It is a scientific mystery that is difficult to solve under the best of circumstances. That effort has been made more difficult by political criticism over the origins of the virus and what international researchers say are moves by China to withhold evidence that could help.
The true origin of the epidemic may not be known for many years, if at all.
How many people have died from Covid-19?
Maybe more than 20 million. The World Health Organization said member states have reported more than 7 million deaths from Covid-19, but the true death toll is expected to be at least three times higher.
In the United States, an average of about 900 people have died weekly from COVID-19 over the past year, according to the Centers for Disease Control and Prevention.
Coronavirus continues to affect older people more than others. Last winter in the United States, people ages 75 and older accounted for about half of all hospitalizations and in-hospital deaths due to COVID-19, according to the Centers for Disease Control and Prevention.
“We cannot talk about Covid in the past, because it is still with us,” said WHO Director Tedros Adhanom Ghebreyesus, Ph.D.
What vaccines have become available?
Scientists and vaccine makers have broken records in the speed of developing COVID-19 vaccines that have saved tens of millions of lives around the world – a crucial step in returning life to normal.
Less than a year after China identified the virus, health authorities in the United States and Britain approved vaccines produced by Pfizer and Moderna. Years of previous research — Including Nobel Prize-winning discoveries Which was key to making the new technology a success – it gave the start to so-called mRNA vaccines.
Today, there is also a more traditional vaccine made by Novavax, and some countries have tried additional options. The rollout of vaccines in poor countries has been slow, but the World Health Organization estimates that more than 13 billion doses of Covid-19 vaccines have been administered globally since 2021.
Vaccines are not perfect. It does a good job of preventing serious illness, hospitalization, and death, and has proven to be very safe, with only rare serious side effects. But protection against mild infections begins to wear off after a few months.
As with influenza vaccines, COVID-19 vaccines must be regularly updated to match the ever-evolving virus, contributing to public frustration with the need for frequent vaccinations. Efforts to develop next-generation vaccines are underway, such as nasal vaccines that researchers hope will do a better job of preventing infection.
Which alternative dominates now?
Genetic changes called mutations occur when viruses make copies of themselves. This virus has proven to be no different.
Scientists named these variables after Greek letters: alpha, beta, gamma, delta, and omicron. Delta, which became dominant in the United States in June 2021, raised a lot of concerns because it was twice as likely to lead to hospitalizations as the first version of the virus.
Then in late November 2021, a new variant appeared on the scene: Omicron.
“It spread very quickly,” and took over within weeks, said Wesley Long, MD, a pathologist at Houston Methodist University in Texas. “This has led to a significant spike in cases compared to anything we have seen previously.”
But on average, the World Health Organization said, it caused less severe illness than delta disease. Scientists believe this may be partly due to immunity building due to vaccination and infection.
“Since then, we continue to see these different sub-omicron variants accumulating more different mutations,” Long said. “Right now, it seems like that’s all [be] Locked on this omicron branch of the tree.”
The CDC said the dominant omicron variant now in the United States is called XEC, which represented 45% of variants circulating nationally in the two-week period ending Dec. 21. Current COVID-19 medications and the latest booster vaccine should be effective against it, because they are “really kind of remixing variants that are already circulating,” Long said.
What do we know about the long coronavirus?
Millions of people remain in limbo with the sometimes crippling, often invisible legacy of the pandemic called “long Covid.”
It may take several weeks to recover after a bout with COVID-19, but some people develop more persistent problems. Symptoms that last for at least 3 months, and sometimes years, include fatigue, cognitive problems known as “brain fog,” pain and cardiovascular problems, among others.
Doctors don’t know why only some people get long Covid. It can occur even after a mild case and at any age, although rates have declined since the early years of the epidemic. Studies show that vaccination can reduce the risk.
It’s also not clear what causes long Covid, which complicates the search for treatments. One important piece of evidence: Researchers are increasingly discovering that remnants of the coronavirus can persist in some patients’ bodies long after their initial infection, though that can’t explain all cases.