COVID SCIENCE-Strong immune response found in …



By Nancy Lapid

November 30 (Reuters) – The following is a summary of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for COVID-19, the disease caused by the virus.

The immune system responds strongly to asymptomatic COVID-19

Asymptomatic people infected with COVID-19 develop robust immune responses that differ from those who become ill, according to a study that appears to contradict previous thinking by health experts. Researchers studied immune system T cells in 76 symptomatic COVID-19 patients and 85 infected people without symptoms and reported their results Friday on bioRxiv ahead of the peer review. Some of these cells – CD8 + T cells – can recognize cells infected with the virus and destroy them. They also produce inflammatory proteins, or cytokines, which help prevent the virus from reproducing. Others, called CD4 helper T cells, help the body make B cells, which make antibodies. All study participants had similar frequencies of T cells able to recognize the virus and destroy infected cells, whether or not they had symptoms. But T cells from asymptomatic individuals produced higher levels of cytokines important to fight the virus, including interferon-gamma and interleukin-2. “What we still need to understand is whether these T cells can persist over time and provide long-term immunity,” said co-author Antonio Bertoletti of Duke-NUS Medical School, Singapore. (Https://bit.ly/37oBDof)

New coronavirus crosses membranes between throat and brain

The new coronavirus uses the nose as a gateway to the brain, autopsy results suggest. The presence of the virus in the brain and cerebrospinal fluid has been linked to neurological symptoms, but the exact way the virus enters the central nervous system has not been clear. During autopsies of 33 patients who died from COVID-19, researchers examined the nasopharynx – the area where the nasal cavity connects to the back of the throat – which happens to be close to the brain. By dissecting the cells and following the path of infection, they saw that the virus invades the brain by passing through the mucous membranes that separate it from the nasopharynx. From there, according to a report published Monday in Nature Neuroscience, it could travel along the nerve fibers that connect the nasal cavity to the part of the brain involved in smell, which would explain “some of the well-documented neurological. symptoms of COVID-19, including changes in smell and taste perception. The researchers also found viral particles in regions of the brain without a direct connection to the nose, suggesting that there may be additional pathways of viral entry into the brain. (Https: //go.nature. com / 2Vl41SU)

University reopening linked to COVID-19 peaks

University communities outside densely populated areas may be particularly vulnerable to the transmission of COVID-19 through the influx of students. The researchers analyzed the impact of reopening US universities with at least 15,000 students in the fall semester 2020 in 80 counties with at least 1 million people, 49 counties with 250,000 to 999,999 residents, and 44 counties with up to 249,999 residents. The reopenings were linked to “dramatic” COVID-19 spikes in counties with fewer than 250,000 residents, while large counties “had flat infection growth rates,” according to Mike Penuliar of Texas Tech University. Infection rates in counties that experienced peaks never returned to pre-reopening levels, his team reported on medRxiv on Sunday ahead of the peer review. “Peaks in rural areas can be terrible,” Penuliar said, noting the dwindling hospital resources, intensive care unit beds and expert medical personnel in these areas. Co-author Billy Philips, also of Texas Tech, added that much of the drop peaks in this study can be attributed to a vulnerable group of people in the general population infected with college students who are more likely to suffer from ‘mild or asymptomatic illness and unwittingly spread the virus. (https://bit.ly/3lpbnPR)

Open https://tmsnrt.rs/3a5EyDh in an external browser for a Reuters graphic on vaccines and treatments in development.

(Reporting by Nancy Lapid; Editing by Bill Berkrot)

Our Standards: Thomson Reuters Trust Principles.


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