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Type A Blood Linked To Higher Rate Of COVID Infections

People with type A blood are likely more susceptible to COVID-19 infections, because the spike protein of the virus shows an affinity for blood group A cells, according to a new study in Blood.

This is the strongest evidence to date to support the idea that blood types influence who is more likely to contract COVID-19.

Moreover, the study shows the spike protein's affinity for type A cells may be amplified by the Omicron strain of the virus.

Lab tests show 25 to 50% increased infection for type A

The study looked at the receptor binding domain (RBD) of SARS-CoV-2, which facilitates host cell engagement. RBD is very similar to galectins, a family of carbohydrate binding proteins that can be studied in a lab setting.

Blood group antigens are carbohydrates, so the authors compared the glycan binding specificity of the SARS-COV-2 RBD with galectins in blood cells from both type A and O. The SARS-CoV-2 virus showed a strong affinity for type A cells. Depending on what virus variant was used, a likelihood of infection increased by 25% to 50% compared to type O cells.

Not only did each RBD recognize blood group A in a glycan array format, the authors explained mutations in variant strains of the virus can be found in regions of the RBD predicted to recognize glycans. Those changes enhanced blood group A binding, the authors said.

Other risk factors more important

These lab findings match clinical observations, which show people with type A blood have demonstrated as much as  a 47% increase in likelihood to get infected with COVID-19.

Among a group of several thousand people, some studies suggest that those with blood group A may be 20% more likely to be infected.

"Among a group of several thousand people, some studies suggest that those with blood group A may be 20% more likely to be infected after exposure to SARS-CoV-2 compared with those who have blood group O. But people with blood group O can still contract the virus and may transmit it to others," said Sean R. Stowell, MD, PhD, of Harvard Medical School, in a press release.

Stowell said, though important, blood type does not rank as high as factors such as age and chronic conditions in determining individuals' risk for severe SARS-CoV-2 infection.

"Blood group is one of many variables that influence one's likelihood of becoming infected following exposure to SARS-CoV-2," he said. "Regardless of their blood group, individuals should be fully vaccinated against COVID-19 and should continue to take other preventive measures appropriate to their risk level."

Ear Infections: Symptoms, Causes And Prevention

Though ear infection is a common term, there are several types of ear infections, each of which have different causes and symptoms.

An outer ear infection (otitis externa) happens when the natural skin flora is disrupted or invades into an otherwise sterile environment in your ears, says Ana Kim, M.D., an otolaryngologist and associate professor of otolaryngology, head and neck surgery at Columbia University Irving Medical Center in New York City. Ear infections can be bacterial, fungal or viral and can affect one or both ears.

A middle ear infection (otitis media) may occur when fluid isn't draining properly from behind the eardrum, located in the middle ear, which commonly happens during an upper respiratory infection, says Dr. Goudy. Swelling and congestion at the back of the nose can lead to a blockage of the eustachian tube, which drains fluid from behind the ear drum into the back of the nose. A middle ear infection can also be caused by bacterial or viral overgrowth behind the eardrum.

"If the eustachian tube can't open and drain effectively (this is why your ears feel stopped up or pressurized during a cold), then the fluid just sits behind the eardrum and can get infected by both bacteria and viruses," explains Dr. Goudy.

The blockage of the ears and eustachian tube are what leads to middle ear infections in both adults and children, but since children tend to contract more colds—between eight and 10 colds before the age of two, according to Pediatrics and Child Health—they're more likely to get ear infections . "The eustachian tube in adults is bigger and more vertically oriented (than in children), which also makes it easier for their ears to drain," says Dr. Gouldy.

Recurrent middle ear infections are defined as three or more ear infections in a six-month period or four or more infections in a year, adds Dr. Goudy.

Types of Ear Infections

Symptoms of ear infections can differ depending on which ear compartment is infected, says Dr. Kim. How long an ear infection lasts depends on several factors, including the cause of the infection, whether the person has underlying medical conditions and the severity of the infection, she says.

Mild symptoms of an outer or middle ear infection might go away without treatment in one to two weeks, especially if the infection is viral, says Karen Hoffmann, M.D., a board-certified otolaryngologist at Piedmont Ear, Nose, Throat and Related Allergy in Atlanta.

"Inner ear infections can last longer, and patients may have some persistent disequilibrium and imbalance even after the acute infection resolves," says Dr. Hoffmann.

Outer Ear Infection

Symptoms of an outer ear infection (otitis externa) include pain, drainage and diminished hearing, according to Dr. Kim.

The outer ear consists of the auricle and external auditory canal, she adds. Its surface is lined by skin acting as a barrier to protect against invasion by unwanted microorganisms. When the skin barrier is compromised, it can turn into an outer ear infection, known as otitis externa.

Outer ear infections are a fairly common condition and are seen most often after frequent water exposure, such as swimmers' ear, says Dr. Hoffmann. They can also be caused by overuse of cotton swabs in the ear canal.

"Typically, patients will have pain, swelling of the ear canal skin, drainage from the ear and hearing loss," Dr. Hoffmann says.

Depending on which part of the outer ear anatomy is involved and the ear infection's cause, diagnosis and treatment varies, says Dr. Kim.

"Ear infections affect people of all ages," she adds. "Folks who cause damage to the delicate outer ear skin by use of mechanical trauma via pins, Q-tips or fingers are prone to developing outer ear infections. Those with skin conditions, such as eczema, psoriasis or dermatitis have compromised outer skin and are thus more prone to an outer ear infection."

Middle Ear Infection

Middle ear infections often include symptoms like ear fullness, pain, diminished hearing, dizziness and, more rarely, facial paralysis. Very young children might be fussy or cry, have trouble sleeping or hearing or might have a fever.

The middle ear is composed of the eardrum, also referred to as the tympanic membrane. The middle ear space behind the eardrum houses the hearing bones, or ossicles, which include three tiny bones called the malleus, incus and stapes, says Dr. Kim.

Commonly called an earache, a middle ear infection, or otitis media, involves the air-containing space behind the eardrum and around the hearing bones. Infections in this part of the ears are common, particularly in children, notes Dr. Hoffman.

Middle ear infections often occur after an upper respiratory infection, such as the common cold, flu, acute sinusitis or COVID-19, adds Dr. Hoffmann.

"The middle ear is a sterile environment, but since it requires the presence of air, it gets it [air] via a connection called the eustachian tube that connects this space with the back of the nose," says Dr. Kim. "The nose, unlike the middle ear, is not a sterile space and can be infected by bacteria, virus and fungus that can subsequently track [travel] up the eustachian tube to enter the middle ear space."

Inner Ear Infection

Inner ear infections primarily involve symptoms of dizziness and hearing loss. These types of ear infections are rare and occur in adults, affecting the cochlea (hearing apparatus) and resulting in nerve hearing loss.

"The balance organ called the vestibule is also part of the inner ear. If this organ is involved, one can experience dizziness and hearing loss," says Dr. Kim.

Inner ear infections increase the risk of meningitis, a condition in which the protective membranes around the brain and spinal cord become inflamed, and can occur as an extension of a middle ear infection, according to Dr. Kim.

Why Astronauts Develop Skin Rashes, Viral Infections In Space

Space travel alters gene expression in white blood cells, weakening the immune system, making astronauts more susceptible to infections and skin rashes while in space, according to a study.

Space travel alters gene expression in white blood cells, weakening the immune system, making astronauts more susceptible to infections and skin rashes while in space, according to a study.

Astronauts on board the International Space Station (ISS) are commonly known to suffer from skin rashes, as well as respiratory and non-respiratory diseases. They are also known to shed more live virus particles, for example Epstein-Barr virus, varicella-zoster responsible for shingles, herpes-simplex-1 responsible for sores, and cytomegalovirus.

These suggest that the human immune system might be weakened by space travel.

"Here we show that the expression of many genes related to immune functions rapidly decreases when astronauts reach space, while the opposite happens when they return to Earth after six months aboard the ISS," said lead author Dr Odette Laneuville, Associate Professor at the Department of Biology of the University of Ottawa.

In the study, published in the journal Frontiers in Immunology, the researchers studied gene expression in leukocytes (white blood cells) in a cohort of 14 astronauts, including three women and 11 men, who resided on board the ISS for between 4.5 and 6.5 months between 2015 and 2019.

Leukocytes were isolated from 4 millilitres of blood drawn from each astronaut at 10 time points: once pre-flight, four times in flight, and five times back on Earth. About 15,410 genes were found to be differentially expressed in leukocytes.

Among these genes, the researchers identified two clusters, with 247 and 29 genes respectively, which changed their expression in tandem along the studied timeline. Genes in the first cluster were dialled down when reaching space and back up when returning to Earth, while genes in the second followed the opposite pattern. Both clusters mostly consisted of genes that code for proteins, but with a difference: their predominant function was related to immunity for the genes in the first cluster, and to cellular structures and functions for the second.

These results suggest that when someone travels to space, these changes in gene expression cause a rapid decrease in the strength of their immune system. However, the data showed that most genes in either cluster returned to their pre-flight level of expression within one year after return on Earth, and typically much sooner — on average, after a few weeks.

Thus, returning astronauts run an elevated risk of infection for at least one month after landing back on Earth. The length of recovery is likely to depend on age, sex, genetic differences, and childhood exposure to pathogens, the researchers said.

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