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More than 100,000 people have been infected with a new corona virus that has spread widely in China in the past few months since it was created. More than 3,000 have already died. Below is our comprehensive guide to understanding and addressing this global public health threat.
This is a rapidly developing epidemic and we will update this guide regularly to keep you as well prepared and informed as possible.
8th of March: First publication of the document.
Table of Contents
How worried should I be?
You should be concerned and take this seriously. But you shouldn't panic.
This is the mantra that public health experts have adopted since the epidemic broke out in January – and it's about as calming as it is easy to achieve. But it is important that we all try.
This new corona virus – called SARS-CoV-2 – is undoubtedly dangerous. It causes a disease called COVID-19, which can be fatal, especially for the elderly and people with underlying health conditions. While the mortality rate among those infected is unclear, even some currently low estimates are seven times higher than the seasonal influenza estimate.
And SARS-CoV-2 is here in the US and it's circulating – we're just beginning to determine where it is and how far it has spread. Problems with federal tests have delayed our ability to detect infection in travelers. And while we are working to catch up, the virus has continued to move. It now appears to be spreading across several communities across the country. It is unclear whether we will be able to move forward and contain it. Even if we can, doing this will take a lot of resources and effort.
All in all, SARS-CoV-2 is not an existential threat. While it can be fatal, around 80 percent of cases are mild to moderate, and people recover within a week or two. There are also obvious, evidence-based measures we can take to protect ourselves, our loved ones, and our communities as a whole.
Now is not the time to panic, which only hinders what you have to do. While it is perfectly understandable to be concerned, it is best to channel this fearful energy into what you can to prevent SARS-COV-2 from spreading.
To do this, you first need complete and accurate information about the situation. To this end, here is our best attempt to answer all questions about SARS-CoV-2, COVID-19 and the situation in the United States.
We start with where it all starts – with the virus itself.
What is SARS-CoV-2?
SARS-CoV-2 stands for severe coronavirus 2 with acute respiratory syndrome. As the name suggests, it is a coronavirus that is related to the coronavirus that causes SARS (severe acute respiratory syndrome). Note: When SARS-CoV-2 was identified for the first time, it was provisionally referred to as a novel 2019 coronavirus or 2019-nCoV.
Corona viruses are a large family of viruses that take their name from the halo of spiked proteins that adorn their outer surface and resemble a crown (corona) under a microscope. As a family, they infect a variety of animals, including humans.
With the discovery of SARS-CoV-2, there are now seven types of coronaviruses known to infect humans. Four circulate regularly in humans and mostly cause mild to moderate infections of the upper respiratory tract – mainly colds.
The other three are corona viruses that have recently jumped from animal hosts to humans and have led to a more serious illness. These include SARS-CoV-2 and MERS-CoV, which causes Middle East Respiratory Syndrome (MERS), and SARS-CoV, which causes SARS.
In all three cases, the viruses are believed to have spread to humans through an intermediate animal host of bats in which a large number of coronavirus strains circulate. Researchers have linked SARS-CoV to viruses in bats that may be transmitted to humans through masked palm trees and raccoon dogs, which were sold for food at street markets for live animals in China. MERS is believed to have spread from bats to dromedary camels before jumping to humans.
Where did SARS-CoV-2 come from?
SARS-CoV-2 is related to coronaviruses in bats, but its host between animals and its route to humans are not yet clear. There has been much speculation that the intermediate tube could be pangoline, but that is not confirmed.
How did it start infecting people?
While the identity of the intermediate host of SARS-CoV-2 remains unknown, researchers suspect that the mysterious animal was present in a live animal market in Wuhan, China, the capital of central China's Hubei province and the epicenter of the outbreak. The market, which was later described as "dirty and untidy" in Chinese state media reports, sold a large selection of seafood and live animals, some of them wild. Many of the initial SARS-CoV-2 infections were associated with the market; In fact, there were many early cases in people who worked there.
Public health experts suspect that market disorder could have led to the spread of the virus. Such markets are notorious for triggering new infectious diseases – they tend to cram people with a variety of live animals that have their own menageries of pathogens. Confined spaces, meat preparation and poor hygienic conditions offer viruses an excessive number of ways to recombine, mutate and jump new hosts, including humans
However, a report in The Lancet describing 41 early outbreaks shows that the earliest identified person suffering from SARS-CoV-2 had no connection to the market. As Ars previously reported, it was a man whose infection caused symptoms on December 1, 2019. None of the man's family members fell ill, and he had no connection to any of the other outbreaks.
The meaning of this and the ultimate source of the outbreak is unknown.
The market was closed and redeveloped by Chinese officials on January 1 as the outbreak started to increase.
What happens if you are infected with SARS-CoV-2?
In humans, SARS-CoV-2 causes a disease that the World Health Organization (WHO) calls COVID-19. As the US Centers for Disease Control and Prevention (CDC) point out, "CO" stands for "Corona", "VI" for "Virus" and "D" for Disease.
What are the symptoms?
COVID-19 is a disease with a range of symptoms and degrees of severity, and we are still learning across the spectrum. So far, it seems to range from mild or possibly asymptomatic cases to moderate pneumonia, severe pneumonia, shortness of breath, organ failure and, in some cases, death.
Many cases begin with fever, fatigue, and mild respiratory problems, such as a dry cough. Most cases don't get much worse, but some develop into a serious illness.
According to nearly 56,000 laboratory-confirmed COVID-19 patients in China, the overview of common symptoms was as follows:
- 88 percent had a fever
- 68 percent had a dry cough
- 38 percent were tired
- 33 percent coughed up phlegm
- 19 percent had difficulty breathing
- 15 percent had joint or muscle pain
- 14 percent had a sore throat
- 14 percent headache
- 11 percent had chills
- 5 percent had nausea or vomiting
- 5 percent had a stuffy nose
- 4 percent had diarrhea
- Less than one percent coughed up blood or bloodstained mucus
- Less than one percent had watery eyes
This data was released in a report by a group of international health experts, compiled by WHO and Chinese officials (the so-called WHO-China Joint Mission) who toured the country for a few weeks in February to assess the outbreak and response efforts.
How severe is the infection?
Most infected people have a mild illness and fully recover in two weeks.
In an epidemiological study with 44,672 confirmed cases in China, written by an emergency team of epidemiologists and published by the Chinese CDC, researchers reported that approximately 81 percent of the cases were classified as mild. The researchers defined mild cases as those ranging from the least symptoms to mild pneumonia. None of the mild cases was fatal; everyone recovered.
About 14 percent of the remaining cases in the study were classified as serious, which was defined as cases with difficulty breathing or shortness of breath, increased respiratory rate and reduced blood oxygen levels. None of the severe cases was fatal; everyone recovered.
Almost 5 percent of the cases were classified as critical. These cases included respiratory failure, septic shock and / or dysfunction or multiple organ failure. About half of these patients died.
Finally, 257 cases (0.6 percent) of severity data were missing.
The overall death rate in the examined patients was 2.3 percent.
Who is most at risk of getting seriously ill and dying?
Your risk of getting seriously ill and dying increases with age and the underlying health conditions.
In the group of 44,672 cases discussed above, the highest death rates were seen in people aged 60 and over. People between the ages of 60 and 69 had a death rate of 3.6 percent. The age group of 70 to 79 year olds had a death rate of about 8 percent, and the 80 year olds or older had a death rate of almost 15 percent.
In addition, the researchers had information on other health conditions for 20,812 of the 44,672 patients. Of those with additional medical information, 15,536 said they had no underlying health conditions. The death rate in this group was 0.9 percent.
Enlarge /. Graph showing the percentage of cases by age group (blue) and death rates within each age group (orange).
The death rate was much higher in the remaining 5,279 patients who reported some underlying health conditions. Those who reported cardiovascular disease had a death rate of 10.5 percent. The death rate in patients with diabetes was 7.3 percent. Patients with chronic respiratory diseases had a rate of 6.3 percent. High blood pressure patients had a death rate of 6.0 percent and cancer patients a rate of 5.6 percent.
Mysteriously, men had a higher death rate than women. In the study, 2.8 percent of adult male patients died, compared to a death rate of 1.7 percent in female patients.
Are men more at risk?
In several studies, researchers found higher case numbers in men than in women. The WHO Joint Mission report found that 51 percent of the cases were men. Another study of 1,099 patients found that men made up 58 percent of the cases.
So far it is unclear whether these numbers are real or whether they would balance out if researchers examined a larger number of cases. It is also unclear whether this bias can reflect differences in exposure rates, underlying health conditions, or smoking rates that can make men more vulnerable.
However, gender differences were found in diseases caused by the relatives of SARS-CoV-2, SARS-CoV and MERS-CoV. There are some preliminary studies to investigate this in mice. Some evidence suggests that the activity of the female hormone estrogen may have a protective effect. Other research has also shown that genes on the X chromosome that are involved in modulating the immune response to viruses can also serve to better protect genetically female people with two X chromosomes than genetic men with only one X chromosome .
Are children less at risk?
Yes, it seems so. In all studies and data to date, children account for tiny fractions of the cases and have reported very few deaths. In the 44,672 cases examined by the Chinese CDC, less than one percent were in children aged 0 to 9 years. None of these cases was fatal. Similar results have been reported in other studies.
The WHO-China Joint Mission report also found that children appear to be largely unscathed from this epidemic. She wrote: "Diseases in children appear to be relatively rare and mild." Previous data show that "infected children were largely identified by adult contact tracking in households".
An unpublished, unreviewed study of 391 cases in Shenzhen, China appears to support this observation. It was found that children in households were as likely to be infected as adults, but had milder cases. The study was released on March 4 on a medical preprint server.
However, according to the Joint Mission report, given the available data, it is not possible to determine the extent of infection in children and what role this plays in disease spread and the epidemic as a whole. "Remarkable," the report continued, "the people interviewed by the Joint Mission Team could not remember episodes in which a child was transferred to an adult."
How long does COVID-19 last?
On average, it takes five to six days from the day you are infected with SARS-CoV-2 to develop symptoms of COVID-19. This pre-symptomatic period – also known as "incubation" – can be between one and 14 days.
According to WHO Director General Dr. Tedros Adhanom Ghebreyesus, led by Dr. Accompanied by Tedros, patients with mild illnesses recover in about two weeks, while patients with more severe cases need three to six weeks to recover.
How many people die from the infection?
This question is difficult to answer. The bottom line is that we don't really know.
The mortality rate (CFR) – that is, the number of infected people who will die from the infection – is simply calculated by dividing the number of deaths by the number of people recovered plus deaths. The CFRs you've probably seen so far were probably a rough version of it: deaths divided by the total number of cases.
One problem with these rough calculations is that the cases we count are not all solved. Some of the currently ill patients can die later. In this situation, patients' cases are counted, but their deaths are not (yet). This distorts the current calculation to make the CFR appear artificially low.
However, a much bigger problem is that we are counting the total number of cases. Because most of the COVID-19 cases known to us are mild, health experts suspect that many more infected people have not introduced themselves to the healthcare providers under test. They may have mistaken their COVID-19 case for a cold or not even noticed it. Areas that are severely affected by COVID-19 may not have sufficient testing capacity to detect all mild cases. If a large number of mild cases are overlooked in the total number of cases, this can cause the CFR to look artificially high.
The best way to overcome this uncertainty is to wait until one of the local outbreaks is completely over, and then do blood tests on the general population to determine how many people have been infected. These blood tests would look for antibodies that target SARS-CoV-2. (Antibodies are Y-shaped proteins that the immune system makes to identify and attack pathogens and other unfriendly invaders.) The presence of antibodies to a particular germ in a person's blood indicates that the person was either exposed to that germ through infection or immunization. Screening the general population for SARS-CoV-2 antibodies provides a clearer picture of how many people were actually infected, regardless of whether they were symptomatic or diagnosed in the event of illness. This number can then be used to calculate an accurate CFR.
Preliminary population screening for COVID-19 infections has been performed in China, particularly in Guangdong Province. The screening of 320,000 people who went to a fever clinic showed that we may not be missing many mild cases. This, in turn, suggests that the CFRs we are now calculating are not much higher than they should be. However, experts still suspect that many mild cases are not reported, and many still believe that the true CFR will be lower than what we are now calculating.
In addition to the correct number of cases and deaths, CFRs are also difficult because they can vary by population, time and location. We have already noted above that the CFR in the patient population increases due to age, gender and underlying health. Over time, however, healthcare providers overall will be better able to identify and treat patients, which will lower CFR.
To make matters worse, the quality of health care varies from place to place. The CFR in a resource-poor hospital can be higher than in a resource-rich hospital. In addition, health systems overwhelmed by an outbreak may not provide optimal care for every patient, thereby artificially increasing CFR in these locations.
This seems to be what we've seen in China so far. In the report of the WHO-China Joint Mission, the experts found that in Wuhan – where the outbreak started and where health systems were destroyed by the number of cases – the CFR was a whopping 5.8 percent. The rest of China had a 0.7 percent CFR at that time.
By March 5, approximately 13,000 cases and 400 deaths were reported outside of Hubei Province (where Wuhan is located). A rough calculation gives a CFR of around 3 percent, but this calculation is likely to drift during the outbreak. We will update the current raw CFR regularly.