Tag Archives: T-cells

Sleep apnea linked to COVID-19 outcomes

By Nancy Lapid

(Reuters) – The following is a summary of some recent studies on COVID-19. They include research that warrants further study to corroborate the findings and that have yet to be certified by peer review.

Sleep apnea tied to severe COVID-19

The risk of severe illness from COVID-19 is higher in people with obstructive sleep apnea and other breathing problems that cause oxygen levels to drop during sleep, researchers say. They tracked 5,402 adults with these problems and found that roughly a third of them eventually tested posted for the coronavirus. While periodic episodes of not-breathing while asleep – leading to low oxygen levels, or hypoxia – did not increase people’s chances of being infected, sleep-related hypoxia did increase infected patients’ odds of needing to be hospitalized or dying from COVID-19, Drs. Cinthya Pena Orbea and Reena Mehra of the Cleveland Clinic and colleagues reported on Wednesday in JAMA Network Open. It is not clear if treatments that improve sleep apnea, such as CPAP machines that push air into patients’ airways during sleep, would also reduce the risk of severe COVID-19, said Pena Orbea and Mehra.

Body’s coronavirus memory may abort new infections

Healthcare workers who did not test positive for COVID-19, despite heavy exposure to infected patients, had T cells that attacked a part of the virus that lets it make copies of itself, according to a report published Wednesday in Nature. Researchers who studied the 58 healthcare workers found their T cells responded more strongly to a part of the virus, called the RTC, that is very similar on all human and animal coronaviruses, including all variants of SARS-CoV-2. They suspect the T cells recognized the RTC because they had “seen” it on other viruses during other infections. That makes the RTC a potentially good target for vaccines if more research confirms these findings, study leaders Mala Maini and Leo Swadling, both of University College London, said in a joint email to Reuters. These data were collected during the first wave of the pandemic, they added. “We don’t know if this sort of control happens for more infectious variants currently circulating.”

Vaccines induce neutralizing antibodies in breast milk

Infants might benefit from COVID-19 antibodies in breast milk regardless of whether mothers acquired the antibodies from being infected with SARS-CoV-2 or from vaccines, according to new findings reported on Wednesday in JAMA Pediatrics. Researchers studied antibodies in breast milk samples from 47 mothers who had been infected with the virus and 30 healthy mothers who had received the vaccines from Moderna or Pfizer/BioNTech. Antibodies from both groups were able to neutralize active SARS-CoV-2 virus, and while antibodies from infection were evident in milk for longer periods, antibody levels from vaccination “were much more uniform,” said study leader Bridget Young of the University of Rochester School of Medicine and Dentistry in New York. Thus, there is likely benefit to getting vaccinated even after a COVID-19 infection because breast milk would then contain a diverse variety of antibodies, she said. The researchers did not study the effect of the antibodies on the babies who consumed the milk.

(Reporting by Nancy Lapid; Editing by Tiffany Wu)

T cell shortage linked to severe COVID-19 in elderly; antiseptic spray may limit virus spread

By Nancy Lapid

(Reuters) – The following is a roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for COVID-19, the illness caused by the virus.

Shortage of ‘naive’ T cells raises COVID-19 risk in elderly

A lower supply of a certain type of immune cell in older people that is critical to fighting foreign invaders may help explain their vulnerability to severe COVID-19, scientists say. When germs enter the body, the initial “innate” immune response generates inflammation not specifically targeted at the bacteria or virus.

Within days, the more precise “adaptive” immune response starts generating antibodies against the invader along with T cells that either assist in antibody production or seek out and attack infected cells.

In a small study published on Wednesday in Cell, COVID-19 patients with milder disease had better adaptive immune responses, and in particular, stronger T-cell responses to the coronavirus.

People over age 65 were much more likely to have poor T cell responses, and a poorly coordinated immune response in general, coauthor Shane Crotty of the La Jolla Institute for Immunology said in a news release.

As we age, our supply of “naive” T cells shrinks, he explained. Put another way, we have fewer “inexperienced” T cells available to be activated to respond to a new invader. “Ageing and scarcity of naive T cells may be linked risk factors for failure to generate a coordinated adaptive immune response, resulting in increased susceptibility to severe COVID-19,” the researchers said.

Antiseptic nasal spray may help limit coronavirus spread

An antiseptic nasal spray containing povidone-iodine may help curb transmission of the new coronavirus, preliminary research suggests.

In test tube experiments, a team of ear, nose and throat doctors found that a povidone-iodine nasal spray inactivated the virus in as little as 15 seconds. The nasal spray they tested is typically used to disinfect the inside of the nose before surgery. Formulations designed for use on skin are not safe in the nose, the researchers note.

They reported on Thursday in JAMA Otolaryngology – Head and Neck Surgery that they now have their patients use the spray before intranasal procedures, to reduce the risk of virus transmission through the air via droplets and aerosol spread.

They also suggest instructing patients to perform nasal decontamination before coming to appointments, to “further decrease intranasal viral load and … prevent spread in waiting areas and other common areas.” They caution, however, that routine use of povidone-iodine would not be safe for some people, including pregnant women and patients with thyroid conditions. Larger clinical trials have not yet proved that viral transmission is curbed by intranasal povidone-iodine solutions, but “these studies are already underway,” the researchers said.

Not all COVID-19 antibody tests are equal

Some COVID-19 antibody tests are much more reliable than others. But even with the best ones, reliability varies among patient subgroups, a new study suggests. Some tests look for IgM or IgA antibodies, the first antibodies produced by the immune system in response to an invader, which do not remain long in the body.

Other tests – the most common kind – look for IgG antibodies, which generally develop within seven to 10 days after symptoms begin and remain in the blood for some time after the patient recovers.

In a study posted on medRxiv on Wednesday in advance of peer review, researchers analyzed data from 11,809 individuals whose COVID-19 had been diagnosed with highly rated tests to see how well the various antibody assays would “recall” that the patient had been infected.

The most commonly used assays, which look for IgG, had a 91.2% recall rate. But the IgA and IgM assays had estimated recall rates of 20.6% and 27.3%, respectively, coauthor Natalie Sheils of UnitedHealth Group told Reuters. “Recall varies significantly across sub-populations and according to timing of the tests, with performance becoming relatively stable after day 14,” she said. “The tests performed better for men versus women, for non-whites versus whites and for individuals above age 45.” More research is needed to understand why these variations occur, Sheils added.

(Reporting by Nancy Lapid; Editing by Bill Berkrot)

T cells play a role in fighting coronavirus; COVID-19 affects children differently

By Nancy Lapid

NEW YORK (Reuters) – The following is a brief roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for COVID-19, the illness caused by the virus.

Immune system’s T cells play a role in attacking the coronavirus

While the immune system’s B cells make antibodies that block the novel coronavirus, its T cells provide another line of attack, according to new research. Researchers found that T cells from recovered patients can target the virus. That is promising news for vaccine developers because it is “consistent with normal, good, antiviral immunity,” Shane Crotty, from the Center for Infectious Disease and Vaccine Research at the La Jolla Institute for Immunology in California, told Reuters. “The types of immune responses targeted by many candidate vaccines are now shown to be the types of immune responses seen in COVID-19 cases that successfully recovered from the disease.” Furthermore, some people who never had COVID-19 nonetheless had T cells that could attack the virus, Crotty’s team reported on Thursday in the journal Cell. This suggests that past exposure to other coronaviruses (such as those that cause the common cold) had somehow primed their T cells to recognize and attack this new coronavirus. That might influence their susceptibility to COVID-19 disease, he said, either preventing them from getting infected or from developing severe disease.

Coronavirus affects adults and children differently

Children appear to have much lower rates of infection with the new coronavirus than adults, but most reports on COVID-19 in youngsters have focused only on small groups. A team of Chinese researchers has analyzed data from 24 earlier studies involving a total of nearly 2,600 children with COVID-19, enabling them to shed light on ways in which the virus acts differently in pediatric patients. They reported on Sunday in the Journal of Medical Virology that the most common laboratory test abnormality observed in adults was a low level of immune cells called lymphocytes (B cells and T cells). This condition, known as lymphopenia, developed in up to 80% of adults but in less than 10% of children. On the other hand, children – particularly infants – were more likely to have elevated levels of cardiac enzymes that indicate heart injury. They also found additional differences. The rates of severe illness and critical illness in adults were 14% and 5%, respectively (according to earlier reports). That compared with 4.4% and 0.9% in children. Fever occurred in up to 99% of adults but in 43% of children; cough in up to 82% of adults but 43% of children. Shortness of breath and acute respiratory distress syndrome (ARDS) were rare in children, but digestive tract symptoms like diarrhea were more common in kids than in grownups.

Coronavirus can infect patients taking hydroxychloroquine

Taking hydroxychloroquine for other medical conditions might not protect against the new coronavirus, French doctors say. The drug had nearly become a standard of care for patients with COVID-19 in many hospitals, even though randomized trials have not yet confirmed its value. But people around the world use decades-old hydroxychloroquine to treat malaria as well as inflammatory conditions like lupus and rheumatoid arthritis, and researchers are seeing occasional cases of coronavirus infection in these patients despite long-term use of the drug. A report on Sunday in the Journal of Antimicrobial Chemotherapy describes two such patients, one with rheumatoid arthritis and the other with a condition called mixed connectivitis. The authors say they also know of at least three other patients in Italy who became sick with COVID-19 despite taking hydroxychloroquine for chronic arthritis. “Patients actually taking long-term hydroxychloroquine are potentially immunosuppressed patients since they are living with chronic inflammatory diseases and thus do not represent the general population exposed to COVID-19,” the French doctors acknowledge. “However, these observational data are not in favor of a universal protective effect of hydroxychloroquine.”

New barcoding technique can help process 100,000 screening tests per day

A big challenge in preventing the spread of the new coronavirus is to identify and quarantine infected people who do not have symptoms. Laboratory workers can test blood samples from thousands of patients per day, still not enough to efficiently screen heavily populated areas. Now researchers at the OSU James Comprehensive Cancer Center in Columbus, Ohio say they have a way to screen over 100,000 samples per day. Their system, dubbed REMBRANDT, makes copies of the virus and introduces two barcodes that simplify patient identification. Barcoding of samples for screening is not new, but the OSU method takes a unique biochemical approach, aiming for a single barcoding and virus-copying step. “Barcodes on products in the supermarket and molecular barcodes for REMBRANDT work the same way,” investigator Richard Fishel told Reuters. “In this case, each patient has a unique combination of letters that allows for their simplified identification. With ten Next Generation sequencing machines, REMBRANDT can test every Ohio resident for COVID-19 infection every 10 days – an important step in contact tracing and reducing the spread of infection.” His team’s report, published on Sunday on the preprint server bioRxiv, has not yet been peer reviewed. “Our next step,” Fishel said, “will be to collaborate with hospitals and public health departments to clinically validate REMBRANDT and make it available to a wider audience.”

(Reporting by Nancy Lapid; Editing by Bill Berkrot)