While it has been claimed that up to 50% of coronavirus patients will remain asymptomatic for the duration of their infection, a new meta-analysis of several studies focusing on the experience of COVID-19 patients suggests that as many as four in five will go on to develop symptoms. The analysis, published in PLOS Medicine and conducted by researchers with the University of Bern in Switzerland, suggests that some patients described as asymptomatic at the time of the study period may later go on to develop symptoms but are unaccounted for in the data.
“The proportion of people who will remain asymptomatic throughout the course of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), is not known,” the authors wrote. “Studies that assess people at just one-time point will overestimate the proportion of true asymptomatic infection because those who go on to develop COVID-19 symptoms will be wrongly classified as asymptomatic rather than presymptomatic.”
The authors said that by taking a closer look at this data, which included 79 studies, there could be a better understanding of the amount and infectiousness of asymptomatic SARS-CoV-2 infection, which in turn could lead to better prevention of transmission. However, they noted that not each data set was a true reflection of the population.
“If the predominate route of transmission is from people who have symptoms, then strategies should focus on testing, followed by isolation of infected individuals and quarantine of their contacts,” the study authors wrote. “If however, most transmission is from people without symptoms, social distancing measures that reduce contact with people who might be infectious should be prioritized, enhanced by active case-finding through testing of asymptomatic people.”
Through their analysis, the study authors said the data does not “support the claim that a large majority of SARS-CoV-2 infections are asymptomatic,” and instead they estimate that the proportion of COVID-19 infections that are asymptomatic throughout the infection period is around 20%.
The implications of their review, the authors argue, suggest that the “contribution of presymptomatic and asymptomatic infections to overall SARS-CoV-2 transmission means that combination prevention measures, with enhanced hand hygiene, masks, testing tracing and isolation strategies and social distancing, will continue to be needed.”
As the COVID-19 pandemic has progressed, medical experts have used several different methods for slowing the spread of the virus. By now, wearing a face mask, practicing social distancing, and regularly washing your hands have practically become second nature. But the use of one other potentially effective preventative measure has hit major snags in the U.S.: contact tracing. In fact, one new study found that half of COVID patients failed to report their close contacts after testing positive.
The research, which was published in the Centers for Disease Control and Prevention’s (CDC) Morbidity and Mortality Weekly Report, focused on a set of patients infected with COVID-19 in North Carolina during a period of “high incidence” of the disease in June and July, during which cases increased 183 percent. Results found that 48 percent of those who had tested positive in Mecklenburg County reported no contacts whatsoever and that 25 percent of those who were reported were unable to be reached.
The study also cited another important finding: The median interval of time between patients first testing positive and successfully notifying those they had been in contact with was six days.
The failure to implement proper contact tracing is not limited to just one state, either: The researchers also point out that in Maryland and New Jersey, 50 percent and 52 percent of reported cases respectively reported no contacts.
“Despite aggressive efforts by health departments, many COVID-19 patients do not report contacts, and many contacts cannot be reached,” the study authors concluded. “Improved timeliness of contact tracing, community engagement, and community-wide mitigation are needed to reduce SARS-CoV-2 transmission.”
The researchers are not alone in their belief that speed and efficiency are key in making contact tracing a useful tool. A study published in the medical journal The Lancet in July analyzed the effectiveness of contact tracing and turnaround time in alerting potentially infected patients. The researchers found that “optimizing testing and tracing coverage and minimizing tracing delays, for instance with app-based technology, further enhanced contact tracing effectiveness, with the potential to prevent up to 80 percent of all transmissions.”
The use of app-based contact tracing hit significant early roadblocks in the United States compared to other countries. But a recent re-release of software known as Exposure Notification Express by Apple and Google was put in to use by public health officials in Maryland, Nevada, Virginia, and Washington, D.C. “I would say this is an improvement,” Jeffrey Kahn, director of the Johns Hopkins Berman Institute of Bioethics, told The Washington Post. “It’s still not probably serving all the interests that public health would want, but it’s better than nothing.” And for more on places where contact tracing could come in handy, check out These Are the States Where COVID Cases Are Skyrocketing.
A new study has found that those who tested positive for COVID-19 were twice as likely to have dined at a restaurant in the 14 days before falling ill.
The study, published by the U.S. Centers for Disease Control and Prevention (CDC) on Friday, looked at symptomatic cases from 11 healthcare facilities in the U.S. between July 1 and 29.
The study’s final sample of 314 eligible participants included 154 people who tested positive for coronavirus and 160 control participants.
Although similar numbers reported always wearing a mask or face covering when in public places (71 percent of positive cases compared to 74 percent of negative cases), the CDC study found that that those who tested positive were twice as likely to have eaten at a restaurant in the two weeks before testing positive. The survey did not ask participants if they had dined indoors or outdoors.
The study said around half of all participants reported shopping and visiting people in their homes in the two weeks before testing.
It also found that similar numbers of people in both positive and negative cases reported visiting gyms, hair salons or a place of worship.
A higher number of those who tested positive reported having had close contact with a confirmed COVID-19 case (42 percent) than those who tested negative (14 percent). Around half the time the contact was a family member, the study found.
Researchers say the findings suggest that people are contracting the virus in areas where they have to remove their masks to eat and drink. Reports of exposure to the virus have been linked to air circulation, they said.
“Direction, ventilation, and intensity of airflow might affect virus transmission, even if social distancing measures and mask use are implemented according to current guidance,” they wrote. “Masks cannot be effectively worn while eating and drinking, whereas shopping and numerous other indoor activities do not preclude mask use.”
They added: “As communities reopen, efforts to reduce possible exposures at locations that offer on-site eating and drinking options should be considered to protect customers, employees, and communities.”
The study’s authors acknowledged the limitations of their study, noting that efforts to match positive and negative cases by age and sex were not maintained for various reasons, such as participants not meeting eligibility criteria, refusing to participate or not responding.
They also noted that participants were aware of their test results which “could have influenced their responses to questions about community exposures and close contacts.”
Working on the basis it was better to be safe than sorry, David continued to self-isolate, changing into clean clothes on the rare occasions he left the front room to visit the bathroom, and eating and sleeping alone.
His wife would bring their 10-month-old daughter Millie to the window of the front room so David could see her through the glass.
The illness left David exhausted and uncertain what was going to happen next.
“Probably one of the most stressful things is trying to work out at what point you ask for help.
“You don’t want to pester the NHS, because there are obviously people in much worse situations than me.
“But certainly, at my weakest moment I didn’t want to fall into the trap of not asking for help and then something bad happening because you didn’t ask for help.
“When I first relapsed, when I first got worse, it’s quite a scary experience because you don’t know if that means you’re going down, down, down.
“So it is quite scary to get worse when you thought you were getting better.”
Felicity, 49, from London, is six weeks into her recovery after first falling ill with Covid-type symptoms.
But like David, her experience has been far from smooth.
“I think the hardest part was having gone through the first 10 days of being very sick and thinking I was getting better, things then getting much, much worse again.
“So it was actually in the fifth week of being ill that my partner had to call A&E because I was experiencing such horrific abdominal pains that I was just calling out in just extreme agony.
“It’s so difficult to know, is that the work of the virus? Is it the immune system’s response? Is it ongoing inflammation?
“I had no problems in my stomach before falling sick, but week five was just horrendous.”
Neither Felicity nor David has been tested for Covid-19, but both were told by doctors they probably had the virus.
They have also been assured they are no longer infectious.
But Felicity struggled to shake off her symptoms and the weeks of illness have taken their toll.
“I spend a huge amount of time in bed trying to recover.
“This entire experience, of being sick and trying to recover, has been mentally overwhelming.”
Most recover quickly
Part of the problem is that so much about the coronavirus is unknown, including why some people experience relatively mild symptoms lasting a few days, while other perfectly healthy people are left struggling for weeks.
Dr Philip Gothard, a consultant physician at London’s Hospital for Tropical Diseases, says the vast majority of patients make a full and fairly rapid recovery.
“Some will have a persisting cough and we’re beginning to see patients who’ve got profound fatigue and exhaustion that goes on perhaps three, four, five or six weeks.
“It’s very distressing if you’re an otherwise young healthy person, it’s something you’re not used to.
“And so it comes as a shock that recovery is slow and stuttering.
“But in many patients with other diseases who are recovering from an acute illness you do tend to see this kind of waxing and waning effect as you are slowly getting better, and you have good days and bad days.”
Tim Spector, professor of genetic epidemiology at King’s College London, says data emerging from the Covid Symptom Study app shows that, on average, it takes people 12 days to start slowly recovering.
“We are also seeing a significant number of people reporting symptoms that can go on much longer than this, in some cases for 30 days or more.
“As we collect more data and continue to use machine-learning and artificial intelligence, we will soon be able to identify which combination of symptoms and risk factors make a person more or less likely to suffer from these longer terms symptoms.”
David and Felicity both hope they are now finally recovering and can start to return to normal life.
But Covid-19, an illness that is still only a few months old, continues to spring surprises on us, and none of them welcome.
Cancer patients — especially those with blood or lung malignancies, or tumors that have spread throughout the body — have a higher risk of death or other severe complications from covid-19 compared with those without cancer, according to a study published Tuesday.
The study, which involved 14 hospitals in Hubei province in central China, where the pandemic emerged, included 105 cancer patients and 536 non-cancer patients of the same age — all of whom had covid-19, the disease caused by the novel coronavirus.
The co-authors, from China, Singapore and the United States, found that cancer patients who developed covid-19 had nearly a threefold higher death rate from the virus than that estimated for the general population. Cancer patients also were more likely to experience “severe events,” such as being admitted to intensive care units and needing mechanical ventilation, than people without cancer. Risk factors included not just age, but also the kind of cancer, the stage and the treatment.
“These findings suggest that patients with cancer are a much more vulnerable population in the current covid-19 outbreak,” the authors concluded.
The study was released at the American Association for Cancer Research’s virtual annual meeting and published in the organization’s peer-reviewed journal, Cancer Discovery. The only previous study of cancer patients and covid-19 included just 18 patients.
Cancer patients are more vulnerable for several reasons, according to the paper’s authors and other experts. Cancer itself depresses the immune system, and patients tend to be older, which is itself a risk factor for serious complications from covid-19. Blood cancers such as leukemia, lymphoma and myeloma attack the immune system, reducing patients’ natural defenses and making them prone to dangerous infections.
Another high-risk group — patients with lung cancer — are likely more vulnerable because of reduced lung function, the authors of the study said. In addition, some treatments, such as chemotherapy and surgery also suppress the immune system. The paper found that even cancer patients who had completed treatment had higher risks of serious covid-19 complications than those who had never had cancer. But those with early-stage disease — localized malignancies — had results similar to those of non-cancer patients.
J. Leonard Lichtenfeld, deputy chief medical officer for the American Cancer Society, which was not involved in the study, called it “important,” adding that it “reflects what we had heard previously — that cancer patients are more susceptible to the virus, and that the course of the infection is worse and the outcomes are worse.” He said that the study was still relatively small and that thousands more patients need to be scrutinized.
The apparent higher risk of death and other serious complications from the virus are among the dangers facing cancer patients as they try to navigate a pandemic that has forced the delays of some treatments, the closing of many clinical trials to new patients and shortages of critical pain medications, said Howard Burris, chief medical officer and executive director of the Sarah Cannon Research Institute in Nashville and president of the American Society of Clinical Oncology.
“We face daunting challenges to optimal patient care,” he said at an ASCO media briefing last week. He noted that some hospitals “have effectively deemed all cancer surgeries elective,” requiring them to be postponed. While such delays make sense for some patients with early-stage disease, they can be devastating for “patients with fast-moving or hard-to-treat cancers,” he warned.
Oncologists also are concerned about delays in cancer tests and screenings, which are crucial for finding and monitoring the disease and include mammograms and colonoscopies. Tests and screenings plunged in the United States since mid-March, according to a new report by Komodo Health, a health data firm, Reuters reported.
More than 1.8 million new cancer cases are expected to be diagnosed in the United States in 2020, according to the American Cancer Society, and more than 606,000 people are expected to die of the disease.
Lichtenfeld said he expects some health-care systems to begin treating more non-covid-19 patients in coming weeks and months. “It won’t be the same in every part of the country,” he said, “but we are starting to move through. That doesn’t mean we are not still at a difficult place, but health systems are trying to figure out the best way to loosen the reins on some elective surgeries.”
For Deborah Silverman, 29, an MD/PhD candidate at MD Anderson Cancer Center in Houston, the outbreak has had a direct impact on her treatment. Diagnosed last year with triple negative breast cancer, one of the most aggressive breast cancers, she has had chemotherapy, surgery and radiation and now is getting chemotherapy again. Even so, Silverman has a 50 to 60 percent chance of recurrence, she said.
To reduce her risk, she planned to enter a clinical trial for immunotherapy, which unleashes the immune system to attack cancer.
But the trial, like many across the country, is not enrolling new patients as a result of the pandemic, so she is extending her chemotherapy regimen. One side effect has been blisters on her feet and toes, making it painful to do yoga or even to walk.
Silverman is hoping she can switch soon to immunotherapy, which has fewer side effects than chemotherapy. “This is the only trial available right now for someone in my position,” she said. “We want to have all the shots on goal we can.”