Global Statistics

All countries
Updated on June 30, 2022 3:52 pm
All countries
Updated on June 30, 2022 3:52 pm
All countries
Updated on June 30, 2022 3:52 pm

Global Statistics

All countries
Updated on June 30, 2022 3:52 pm
All countries
Updated on June 30, 2022 3:52 pm
All countries
Updated on June 30, 2022 3:52 pm
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What Percentage Of Covid Cases Are Asymptomatic

Percent Of People With Covid

CDC: Asymptomatic spread leading latest COVID-19 surge

We all step backward a few paces when we hear a cough or sneeze, adding distance between ourselves and the germs of COVID-19 or the common cold. But new research has found that about 30 percent of those infected with coronavirus show no symptoms.

Theyre called asymptomatic carriers. South Korean researchers findings about them add to the mystery and frustration surrounding COVID-19, now in its second global wave. That they so prolifically and unknowingly spread the infection makes the virus both difficult to contain and challenging to track.

The study, published in Journal of the American Medical Society Internal Medicine, indicates these asymptomatic people carry as much virus in their nose, throat and lungs as people exhibiting symptoms. They also carry, and spread it, for almost as long.

The team differentiated between people who are asymptomatic and merely pre-symptomatic, meaning the latter who eventually become ill with COVID-19. They did this by measuring the virus genetic material in 193 symptomatic and 110 asymptomatic people who were kept isolated at a community treatment center where they were monitored constantly.

Of those considered asymptomatic initially, 89 remained healthy throughout the study. Twenty-one others went on to develop symptoms of the virus.

You Can Still Have Lingering Issues From Covid Following An Asymptomatic Case

An asymptomatic case could also still affect you long-term. In fact, several studies have shown that long-term health issues arise in those who had COVID but had no symptoms. Eric J. Topol, MD, founder and director of Scripps Research Translational Institute, told TheWall Street Journal that at least four studies so far have analyzed the lung scans of asymptomatic individuals, finding that “half have significant abnormalities consistent with COVID pneumonia but without symptoms.” And a July study published in JAMA Cardiologydiscovered abnormal cardiac MRIs in both symptomatic and asymptomatic COVID patients, concluding that heart damage due to the virus is possible no matter how mild or severe your case is.

“There is a risk of internal hits to these people that they are unaware of,” Topol said. “When things happen slowly in a person, below the surface, you can end up with a chronic situation.” And for more on how the virus can progress, If You’ve Done This, You’re Twice as Likely to Develop Severe COVID.

Children Much More Likely To Have Asymptomatic Cases Of Covid

Children are much more likely to have cases of COVID-19 without showing symptoms than adults, according to a new study.

Roughly half the children between 0 and 11 years old who tested positive for COVID-19 across households studied in New York City and some counties in Utah showed no symptoms, researchers found. Almost half the kids 12 to 17 had COVID-19 without symptoms.

That compared to just 12 percent of adults 18 or older not having symptoms from the disease.

The study followed 1,236 people in 310 households between September 2020 through April to track asymptomatic and symptomatic infections. Participants self-collected nasal swabs.

The study found similar COVID-19 infection rates across age groups, though the risk of infection was higher in New York City.

Forty of the households had one or more COVID-19 infections during the study period. Ninety-four participants tested positive.

The study was well-designed, Dr. Monica Gandhi, professor of medicine at the University of California, San Francisco, told The Epoch Times.

They could basically stratify that 0 through 4, 5 to 11, and then going up from there are very unlikely to get sick, Gandhi said.

Researchers, including Dr. Fatimah Dawood with the Centers for Disease Control and Prevention, said the study showed that households remain a common site for transmission of the virus that causes COVID-19.

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Avoid Large Thanksgiving Gatherings This Year

Beckham and researchers at his lab study viruses similar to coronaviruses called flaviviruses. They include common viruses like West Nile, Dengue, tick-borne encephalitis and Zika virus. Throughout the pandemic, Beckham and researchers in his lab have been studying various aspects of SARS-CoV-2. Hes assisting with vaccine trials and is leading a clinical trial related to convalescent plasma. The results of that research are due out soon.

Like many medical experts, Beckham has canceled his plans to celebrate Thanksgiving with extended family. He and his wife will celebrate on their own with their children this year.

Its sad that we have to do this this year. But, were all working hard on vaccines and Im hoping we can have a normal Thanksgiving next year, Beckham said.

Until we have vaccines, he encouraged individuals to do as much as they can now to tamp down spread of the virus so we can all enjoy great gatherings and milestones in future years.

Its hugely important for people to understand that there are a lot of asymptomatic people and theres a lot of asymptomatic spread, Beckham said.

But, we can protect each other if we just do simple things.

Massive New Analysis Confirms Just How Many Covid

CDC estimates 35 percent with coronavirus may be ...

Within months of SARS-CoV-2‘s emergence as a global catastrophe it was becoming clear that many who spread the disease did so unwittingly, experiencing not so much as a tickle in their throat to alert them of the danger within.

Distinguishing those who are truly asymptomatic from those who are simply yet to show signs of the virus has made it hard to calculate a precise figure on the risks of succumbing to the illness.

Now an analysis by a group of US medical researchers on more than 350 studies has found just over 35 percent of all COVID-19 infections don’t proceed to a symptomatic phase.

Early estimates ranged from just 4 percent of infections being asymptomatic, all the way up to 81 percent. Even as the pandemic ensued, figures conservatively estimated fewer than 20 percent of people might be infectious without showing any signs.

Confidently nailing down a number is harder than it might seem. Without the fever, loss of smell, sore throat, aches, and cough to encourage a trip to a clinic, few people bother lining up for a test.

One of the simplest ways to capture the true spread of infection is to conduct a cross-sectional survey, randomly sampling a population to detect the presence of the virus regardless of the subject’s health.

There’s just one problem with this approach. Anybody who’s feeling well on the day they’re tested can potentially fall sick hours or days later, making ‘no symptoms’ look the same like ‘no symptoms… yet’.

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Is It Common For Viruses To Affect People Of Varying Ages Differently

Age also seems to affect the degree to which people are asymptomatic when they contract a virus. The Duke study of children with COVID-19 found that asymptomatic cases were highest among kids ages 6 to 13. Asymptomatic cases were less common but still occurred 25% of the time in children ages 0 to 5 and teens who were 14 to 20 years old. The study did not look at adults, but older people have fared worse when they get COVID-19.

Beckham said its quite common for different viruses to affect people of various ages in different ways. Some can be more severe in children or young adults. Other infectious illnesses like SARS-CoV-2 and the flu are more dangerous to older people. People with underlying health conditions and older people have been among those who have been most critically ill and who have died at higher rates from COVID-19.

Kids seem to have lower overall rates of infection, but they clearly can get infected and they can be asymptomatic, Beckham said. Theres still a lot of work to be done to understand the epidemiology of these younger kids. I dont think we know exactly what role they play in the spread of the virus.

While researchers have much more to learn about how common asymptomatic cases of COVID-19 are and exactly how asymptomatic spread occurs, theres plenty of evidence to warrant concern and careful behavior now.

Beckhams take-home message to reduce asymptomatic spread boils down to this simple advice. Wear your mask.

Children And The Elderly

The study authors found that of the truly asymptomatic cases they analyzed, nearly 47% were children and 20% were elderly. This age discrepancy was significant.

This is not entirely surprising because the elderly tend to have multiple medical conditions, and they are among the most vulnerable population to infection, Singer says. Their immune systems are frequently not up to snuff so to speak. I think this does not come as a shock to anybody, but this work nails it down with COVID.

What this shows us is that screening for symptoms is not enough when kids go back to school, Singer says. We need to get vaccines approved for children. They need to be vaccinated to help block transmission chains.

The authors also report that independent of age, people with comorbidities had significantly lower rates of asymptomaticity compared to those with no underlying medical conditions. While this finding is not new, it lends validity to the studys methods and major findings.

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Outcome Variable And Data Extraction

The outcome variable of this study was the magnitude of true asymptomatic SARS-CoV-2 infection. Asymptomatic SARS-CoV-2 infection is defined as an individual without a history of clinical signs and symptoms throughout the course of infection. Two experienced review authors extracted all essential data from the included studies using a predesigned data extraction form. The data extraction form organized as the last name of the first author, the country of the study conducted, data collection period, sample size, magnitude of asymptomatic COVID-19 cases. Any inconsistencies in the data extraction process were decided through discussion involving all authors.

Asymptomatic Carriers Represent 50% Of Driving Force Behind Covid

Orange County sees rise in asymptomatic coronavirus cases

Determining the actual number of asymptomatic COVID-19 cases has been a significant challenge for researchers and public health officials. The U.S. Centers for Disease Control and Prevention (CDC0 estimates that about 40 percent of coronavirus carriers are asymptomatic.

In a study out last month, CDC researchers found that 59 percent of all COVID-19 transmission came from asymptomatic people, defined by the CDC as those who are infectious before developing symptoms and individuals who never experience symptoms.

The latest study, however, indicates that asymptomatic cases might represent an even larger majority of COVID-19 infections. Researchers at the University of Chicago reviewed the initial COVID-19 outbreak in New York City. They found that just 13 percent to 18 percent of COVID-19 cases were symptomatic between one in five and one in seven.

Moreover, the research team found that non-symptomatic cases substantially contribute to community transmission, making up at least 50 percent of the driving force of COVID-19 infections. Thats just slightly lower than the CDC studys 59 percent estimate.

The researchers created a formula based on antibody tests taken in New York City from March to April, along with the citys recorded cases from March to June. They also looked at New Yorks testing capacity during that time. Their findings were published in the Proceedings of the National Academy of Sciences.

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Only 20% Remained Asymptomatic

The new study, published today in PLOS Medicine, reviewed information gathered early in the pandemic to find that most coronavirus infections will show symptoms at some point during infection.

The researchers from the University of Bern in Switzerland reviewed studies conducted in the early weeks of the pandemic using a database of SARS-CoV-2 evidence from March and June of this year.

Their findings suggest only an estimated 20 percent of infections remained symptom-free.

They specifically analyzed 79 studies containing data on more than 6,000 people, with about 1,300 defined as asymptomatic, to determine the proportion of people with an infection who never developed symptoms.

But this didnt mean the person couldnt spread the virus.

Keep in mind that a person with either asymptomatic or presymptomatic SARS-COV-2 infection can still transmit the virus, study authors Diana Buitrago-Garcia, a PhD student, and Nicola Low, a professor of epidemiology and public health at the Institute of Social and Preventive Medicine at the University of Bern in Switzerland, told Healthline in a joint emailed statement.

Zeroing In On The Asymptomatics

The team sifted through the literature to pinpoint studies which identified cases where people never developed symptoms over time, despite testing positive for COVID-19. Studies in which people lacked symptoms at the time of their testing, but later developed symptoms, were also excluded.

A big source of bias is when the presymptomatic cases are mistakenly called asymptomatic, says Singer, who is also affiliated with UF’s Emerging Pathogens Institute. Including them gives too high a number, it sends a false signal.

The team also minimized bias in their findings by excluding from their analysis all index cases. This refers to the first case identified in an outbreak cluster, which may or may not include symptoms. Because of the uncertainty, data involving these cases was not considered.

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At Least A Third Of Coronavirus Infections Are Asymptomatic

Coronavirus temperature checkpoint.


The pandemic has corrected several common misconceptions about health, like the assumption that you only catch and spread infectious disease when you seem sick.

At one extreme, the measles virus always reveals signs of infection, whereas at the other end, many of those infected with polio virus show no clear symptoms.

Where does the SARS-CoV-2 coronavirus sit on that scale of causing symptoms?

Researchers have now estimated the proportion of infected people who never develop symptoms of Coronavirus Disease.

The research by Daniel Oran and Eric Topol from Scripps Research Translational Institute in La Jolla, California, involved a systematic review of reports that tested for Covid. Those tests either looked for current viral infection through PCR analysis or via past infection, as indicated by antibody testing the presence of antibodies against the SARS-CoV-2 virus.

Oran and Topol’s review, published in Annals of Internal Medicine, found 61 reports, 43 of which used PCR after collecting nose/mouth swabs, and 18 that had performed antibody testing.

The study aimed to count the number of people who never have symptoms of Covid asymptomatic cases and exclude those who initially show no signs but then eventually develop the disease. As it’s only possible to identify the latter presymptomatic cases in retrospect, the study only considered reports with a follow-up period that tracked whether Covid appeared later.

Who Are The Asymptomatic With Covid

All 41 new COVID

Increasingly there is evidence that even though COVID-19 is more deadly than seasonal flu, many of us mount an immune defense leaving us asymptomatic.

A PCR test is positive for a limited time, primarily around the time of symptoms, so PCR based data, while definitive, is rarely applied for the asymptomatic and would most likely under-report COVID-19 as we test too far before or after that temporal sweet spot. Evidence of our immune system responding to COVIDs presence, found in antibodies in our serum, lasts for more extended periods and may give us more accurate but still unreported values. Several studies have looked for the presence of COVID-19 in specific populations, like first-responders. The current research tries to get a more inclusive community snapshot using individuals coming into the healthcare system for elective reasons, checkups, or elective surgery. Yes, it is not generalizable, but lets see what we might learn.

The study involved 4841 individuals in Virginia undergoing routine laboratory testing or visits all screened to exclude symptoms of COVID-19. They were a bit younger, more female, white, and concerned and careful about COVID-19. The outcome was the presence of COVID-19 IgG antibodies.

  • Younger, less than 50
  • Contact with a COVID-19 positive individual
  • Working outside the home or in a health care setting

This article was updated due to an editing error on the part of the author.

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Modeling The Epidemic Of Covid

To consider asymptomatic infected individuals, we constructed the susceptible-exposed-asymptomatic-confirmed-unconfirmed symptomatic-hospitalized-removed model by extending the classic susceptible-exposed-infectious-removed model to include asymptomatic cases, unconfirmed symptomatic cases who did not seek medical attention or get tested for mild symptoms, and quarantined confirmed cases. In this model, we divided the population into seven compartments: S , E , A , I , U , H , and R . Susceptible individuals could acquire the virus after contact with infected cases and became latent when they were infected but non-infectious. After a period of time, some of the latent individuals developed into symptomatic infections some of these were confirmed and treated until they progressed into the removed stage and some went unconfirmed because they did not present themselves to healthcare facilities or get tested for mild symptoms. Others developed into asymptomatic infections and remained infectious until they progressed into the removed stage. Removed stage included individuals who were recovered or had died .

Figure 2. Schematic diagram of SEAIUHR model propagation process. S, susceptible E, latent A, asymptomatic infectious I, confirmed symptomatic infectious U, unconfirmed symptomatic infectious H, hospitalized R, removed.

Dynamics of these seven parts over time could be expressed by the following ordinary differential equation:

Most People Who Get The Coronavirus Don’t Develop Symptoms

Asymptomatic infections are difficult to spot and quantify, since most people who feel fine aren’t inclined to see a doctor or get tested.

Subramanian’s model was able to distinguish between symptomatic cases that weren’t recorded due to a lack of testing and asymptomatic cases people who never got sick or may not have known they were sick due to very mild symptoms.

The team’s resulting estimate may be higher than others because their model used a broader definition of asymptomatic cases it included people whose symptoms were so mild that they never made contact with the healthcare system.

But other models may also underestimate the prevalence of asymptomatic infections by relying on data from the start of the pandemic, Subramanian said. For instance, early takeaways about the rate of asymptomatic cases on cruise ships or in nursing homes may no longer hold true for the general population.

At the very least, Subramanian said, his study indicates that most coronavirus cases don’t develop symptoms.

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