Pandemic research news thread (COVID-19, SARS-CoV-2, coronavirus)

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People with blood type O may have lowest risk of COVID-19; those with type A & AB increased risk of severity

RELEASE: Two studies published today in Blood Advances suggest people with blood type O may have a lower risk of COVID-19 infection and reduced likelihood of severe outcomes, including organ complications, if they do get sick.

As the pandemic continues, the global biomedical research community is working urgently to identify coronavirus risk factors and potential therapeutic targets. The potential role of blood type in predicting risk and complications of COVID-19 infection has emerged as an important scientific question. These new studies add evidence that there may be an association between blood type and vulnerability to COVID-19; however, additional research is needed to better understand why and what it means for patients.

Blood type O may offer some protection against COVID-19 infection, according to a retrospective study. Researchers compared Danish health registry data from more than 473,000 individuals tested for COVID-19 to data from a control group of more than 2.2 million people from the general population. Among the COVID-19 positive, they found fewer people with blood type O and more people with A, B, and AB types.

The study results suggest that people with blood types A, B, or AB may be more likely to be infected with COVID-19 than people with type O. The researchers did not find any significant difference in rate of infection between A, B, and AB types. Since blood group distributions vary among ethnic subgroups, the researchers also controlled for ethnicity and maintained that fewer people with blood type O tested positive for the virus.

"It is very important to consider the proper control group because blood type prevalence may vary considerably in different ethnic groups and different countries," said study author Torben Barington, MD, of Odense University Hospital and the University of Southern Denmark. "We have the advantage of a strong control group -- Denmark is a small, ethnically homogenous country with a public health system and a central registry for lab data -- so our control is population-based, giving our findings a strong foundation."

Blood groups A and AB associated with increased risk of severe clinical outcomes of COVID-19 infection People with blood groups A or AB appear to exhibit greater COVID-19 disease severity than people with blood groups O or B, according to a separate retrospective study. Researchers examined data from 95 critically ill COVID-19 patients hospitalized in Vancouver, Canada. They found that patients with blood groups A or AB were more likely to require mechanical ventilation, suggesting that they had greater rates of lung injury from COVID-19. They also found more patients with blood group A and AB required dialysis for kidney failure.

Together, these findings suggest that patients in these two blood groups may have an increased risk of organ dysfunction or failure due to COVID-19 than people with blood types O or B. Furthermore, while people with blood types A and AB did not have longer overall hospital stays than those with types O or B, they did remain in the intensive care unit (ICU) for a longer average time, which may also signal a greater COVID-19 severity level.

"The unique part of our study is our focus on the severity effect of blood type on COVID-19. We observed this lung and kidney damage, and in future studies, we will want to tease out the effect of blood group and COVID-19 on other vital organs," said study author Mypinder S. Sekhon, MD, of the University of British Columbia. "Of particular importance as we continue to traverse the pandemic, we now have a wide range of survivors who are exiting the acute part of COVID-19, but we need to explore mechanisms by which to risk stratify those with longer-term effects."

Stay in touch with your emotions to reduce pandemic-induced stress

EXCERPT: ... The good news, Emily Kroska adds, comes from a new study she led that shows how people might reduce their distress. In that study, Kroska's research team surveyed Americans' responses to various situations wrought by the coronavirus pandemic. The team found that those who took stock of their emotions--be they sadness, anxiety, fear, loneliness, and the like--and then addressed those emotions with mindful action--such as calling a friend or family member­--reported lower stress levels than those who steered away from identifying with their emotions or did not gauge the potential effects of their behavior... (MORE - details)
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Low risk of COVID-19 infection found among people with congenital heart disease

RELEASE: Results of a retrospective analysis suggest that people born with a heart defect who developed COVID-19 symptoms had a low risk of moderate or severe COVID-19 infection, according to a new article published today in the Journal of the American Heart Association, an open access journal of the American Heart Association.

In what may be the largest study of its kind to date, researchers at Columbia University Vagelos College of Physicians and Surgeons in New York City explored the impact of COVID-19 infection on patients with congenital heart disease (CHD). The specialty center follows more than 7,000 adult and pediatric patients born with a heart defect. Fifty-three CHD patients (median age 34) with COVID-19 infection were reported at their center between March and July 2020.

“At the beginning of the pandemic, many feared that congenital heart disease would be as big a risk factor for COVID-19 as adult-onset cardiovascular disease” the researchers wrote. However, they are “reassured by the low number of patients treated at their center and the patients’ outcomes.”

Among the 43 adults and 10 children with a congenital heart defect infected with COVID-19, additional characteristics included: 58% had complex congenital anatomy; 15% had a genetic syndrome; 11% had pulmonary hypertension; and 17% had obesity. Additional analysis found:

The presence of a concurrent genetic syndrome in all patients and advanced physiologic stage in adult patients were each associated with an increased risk of symptom severity.
Five patients had trisomy 21 (an extra chromosome at position 21); four patients had Eisenmenger’s syndrome (abnormal blood circulation caused by structural defects in the heart); and two patients had DiGeorge syndrome (a condition caused by the deletion of a segment of chromosome 22). Nearly all patients with trisomy 21 and DiGeorge syndrome had moderate/severe COVID-19 symptoms.

As for outcomes among all 53 patients with CHD: nine patients (17%) had a moderate/severe infection, and three patients (6%) died. In addition, the researchers note several limitations to their analysis:

“While our sample size is small, these results imply that specific congenital heart lesions may not be sufficient cause alone for severe COVID-19 infection. While it is possible that our patient population exercised stricter adherence to social distancing given early publicized concerns about cardiac risk, these early results appear reassuring. …the median age and the frequency of acquired cardiac risk factors were lower in hospitalized patients in our cohort compared to published reports of hospitalized patients from COVID-19 in NYC at large. This may be because the CHD community, at large, is younger than the general population or because individuals with CHD may have distinct risk factors for severe COVID-19 infection when compared to the general population. It is possible that a cohort of elderly CHD patients might have a different risk profile than the general population.”

The researchers concluded, “Despite evidence that adult-onset cardiovascular disease is a risk factor for worse outcomes among patients with COVID-19, patients with CHD without concomitant genetic syndrome, and adults who are not at advanced physiological stage, do not appear to be disproportionately impacted.”

Aerosols vs Droplets

RELEASE: Winter is on its way. And in this year of coronavirus, with it comes the potential for a second wave of COVID-19. Add in flu season and our tendency to head inside and close our windows to the cold, wet weather, and it appears the next several months are going to present us with new health challenges.

UC Santa Barbara researchers Yanying Zhu and Lei Zhao hope to arm people with better knowledge of how SARS-CoV-2 spreads as the seasons change. Their new study investigates the secret of this virus’s unusual success: its transmissibility, or how it manages to get from host to host. The dominant mode, it turns out, changes according to environmental conditions.

“Back at the beginning of April a lot of people were wondering if COVID would go away in the summer, in the warmer weather,” said Zhu, a professor of mechanical engineering and one of the authors of a paper that appears in the journal Nano Letters. “And so we started to think about it from a heat transfer point of view, because that’s what our expertise is.”

The virus, of course, did not disappear during the summer as hoped, and in fact COVID cases across the country continued to climb. To understand how the novel coronavirus manages to persist in circumstances in which the flu virus fails, Zhu, Zhao and colleagues modeled different temperatures and relative humidities along a continuum from hot and dry to cold and humid in typical indoor spaces, where the virus is distributed by normal speech and breathing — and, according to the paper, where people “only sneeze or cough into a tissue or their elbows.” To these scenarios they added emerging knowledge about the highly contagious microbe; in particular, how long it remains infectious outside a host.

The results are sobering. For one thing, respiratory droplets — the most common mode of transmission — don’t obey our social distancing guidelines.

“We found that in most situations, respiratory droplets travel longer distances than the 6-foot social distance recommended by the CDC,” Zhu said. This effect is increased in the cooler and more humid environments to distances of up to 6 meters (19.7 feet) before falling to the ground in places such as walk-in refrigerators and coolers, where temperatures are low and humidity is high to keep fresh meat and produce from losing water in storage. In addition to its ability to travel farther, the virus is particularly persistent in cooler temperatures, remaining “infectious from several minutes to longer than a day in various environments,” according to several published studies.

“This is maybe an explanation for those super-spreading events that have been reported at multiple meat processing plants,” she said.

At the opposite extreme, where it is hot and dry, respiratory droplets more easily evaporate. But what they leave behind are tiny virus fragments that join the other aerosolized virus particles that are shed as part of speaking, coughing, sneezing and breathing.

“These are very tiny particles, usually smaller than 10 microns,” said lead author Lei Zhao, who is a postdoctoral researcher in the Zhu Lab. “And they can suspend in the air for hours, so people can take in those particles by simply breathing.

“So in summer, aerosol transmission may be more significant compared to droplet contact, while in winter, droplet contact may be more dangerous,” he continued. “This means that depending on the local environment, people may need to adopt different adaptive measures to prevent the transmission of this disease.” This could mean, for example, greater social distancing if the room is cool and humid, or finer masks and air filters during hot, dry spells.

Hot and humid environments, and cold and dry ones, did not differ significantly between aerosol and droplet distribution, according to the researchers.

The quantitative descriptions of virus propagation under varying local conditions could serve as useful guidance for decision-makers and the general public alike in our efforts to keep the spread to a minimum.

“Combined with our study, we think we can maybe provide design guidelines for the optimal filtering for facial masks,” said Zhao, adding that the research could be used to quantify real exposure to the virus — how much virus could land on one’s body over a certain period of exposure. This knowledge could, in turn, lead to better strategies for airflow and ventilation to prevent virus accumulation. In addition, the insights, according to the study, “may shed light on the course of development of the current pandemic, when combined with systematic epidemiological studies.”

Obesity implies high risk of severe COVID-19 regardless of age, sex, ethnicity and pre-existing diseases

RELEASE: The probability that an obese person will develop severe COVID-19 is high regardless of age, sex, ethnicity, and the presence of co-morbidities such as diabetes, high blood pressure, and heart or lung disease, according to a study by Brazilian researchers published in Obesity Research & Clinical Practice.

The systematic review and meta-analysis of relevant data in the scientific literature focus on nine clinical studies, which in aggregate reported the evolution of 6,577 COVID-19 patients in five countries. The authors conclude that obesity is itself a factor that favors rapid progression to critical illness requiring intensive care and significantly increases the risk of death. The associated research project was supported by FAPESP.

“Several factors contribute to the progression to critical illness in the obese organism. One is the limited capacity to produce interferons [a class of proteins secreted by defense cells and essential to inhibit viral replication] and antibodies. In addition, adipose tissue functions as a reservoir for the virus, maintaining it in the organism for longer,” said Silvia Sales-Peres, a professor at the University of São Paulo (USP) in Bauru and principal investigator for the project.

This potentially higher viral load, she explained, is not the only problem faced by patients with a high body mass index (BMI). Recent research shows that the chronic low-grade inflammation typical of obesity – caused by excessive expansion of adipose cells – makes the inflammatory cytokine storm triggered by SARS-CoV-2 even more damaging to the lungs.

“Obese patients usually present with impaired respiratory function, as abdominal adipose tissue compresses the diaphragm and prevents it from moving normally,” Sales-Peres said. “In sum, various concurrent factors make these patients more predisposed to dependency on mechanical ventilation and other kinds of intensive care if they contract COVID-19. In the studies we analyzed, 9.4% of the obese patients treated in intensive care units died.”

Risk scale

BMI is a measure of body fat proportional to height and weight that applies to adult men and women and is considered the international standard for diagnosing malnutrition and obesity. It is calculated by dividing weight in kilograms by height in meters squared. Generally speaking, overweight corresponds to a BMI of 25 or more, while 30 or more indicates obesity. Almost 60% of Brazilians are overweight and some 20% are obese, according to the Health Ministry’s telephone surveillance survey on risk factors for chronic diseases (Vigitel).

“A higher degree of susceptibility to the novel coronavirus when a person reaches a certain number on the BMI scale is no accident. Impaired antibody production and chronic inflammation favor progression of COVID-19 in overweight subjects,” Sales-Peres said. “Our analysis also showed that the risk associated with obesity is even greater for smokers or subjects with co-morbidities such as diabetes, hypertension, and lung disease.”

She went on to argue that studies like this are important both to alert patients to the need to protect themselves against the virus and to help health services prepare for the potential demand for intensive care. “We embarked on the study in April when it wasn’t so clear that obesity would be considered a major risk factor for COVID-19,” she said.

For the systematic review, the authors first searched Medline, Embase, Web of Science, BVS/Lilacs, SciELO, Scopus, and Google Scholar to select studies published on or before April 27 using key terms such as obesity and COVID-19. They identified 40 and ended up with eight that matched the inclusion criteria and were considered worthy of meta-analysis because they contained scientific evidence at the highest level to orient clinical practice.

“The 2018 Vigitel survey pointed to 30% growth in the overall prevalence of overweight in Brazil compared with 2006. Considering only the 18-24 group, the increase was 55.7%. This makes discussing the risk of severe COVID-19 associated with obesity extremely important,” Sales-Peres said.

Public health policy should promote an integrated and intersectoral approach to obesity, she argued, and should have regulatory and enforcement authority. “There should be a transformational mobilization to encourage outdoor physical exercise and healthy dietary habits from early childhood,” she said. “This should be a coordinated initiative across all three tiers of government so as to enable integrated planning, funding, and strategy to promote wellness and prevent obesity.”

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