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COVID SCIENCE-Vaccinated COVID-19 patients appear less contagious; arthritis drug in spotlight

Nancy Lapid
·3 min read

By Nancy Lapid

Feb 12 (Reuters) - The following is a roundup of some of thelatest scientific studies on the novel coronavirus and effortsto find treatments and vaccines for COVID-19, the illness causedby the virus.

COVID-19 post-vaccination may be less contagious

People who get a COVID-19 vaccine can still become infectedwith the novel coronavirus, although they are likely to beprotected against severe illness, and a new study suggests theyalso may be less contagious. At a large Israeli healthmaintenance organization where 650,000 members received thetwo-dose vaccine from Pfizer Inc and BioNTech SE, researchers identified 2,897 patients who latertested positive for COVID-19. The amounts of virus on swabsamples from the nose and throat were reduced four-fold forinfections occurring at least 12 days after the first dose ofvaccine compared to what is typically seen in unvaccinatedCOVID-19 patients, the research team from Maccabi HealthServices and the Technion - Israel Institute of Technologyfound. Viral loads are known to be linked with contagiousnessand disease severity. But this study was not a randomized trialand it did not look at patients' viral loads over time, nor therates at which their contacts became infected, which would bethe most direct evidence of whether a vaccine reduces virustransmission. Still, the authors concluded in a paper posted onMonday on the medical website medRxiv ahead of peer review,"These reduced viral loads hint to lower infectiousness, furthercontributing to vaccine impact on virus spread." (https://bit.ly/2LK5HnE)

Study shows range of COVID-19 benefits from arthritis drug

A large study adds to evidence that Roche'sarthritis drug tocilizumab, sold under the brand name Actemra,cuts the risk of death among hospitalized patients withCOVID-19, shortens their hospital stays and reduces their needfor mechanical ventilation. The randomized trial involved morethan 4,000 patients with varying degrees of illness. Some neededonly simple oxygen therapy while others needed mechanicalventilation. Most also were receiving a steroid such asdexamethasone. The rate of death within 28 days was 29% forpatients in the tocilizumab group and 33% in the control group,according to a report posted on Thursday on the medical websitemedRxiv ahead of peer review. After accounting for patients'age, sex and other risk factors, tocilizumab was associated witha 14% reduction in the risk of death. "We now know that thebenefits of tocilizumab extend to all COVID patients with lowoxygen levels and significant inflammation," study co-leaderPeter Horby of the University of Oxford said in a pressstatement. Used in combination with steroids, Horby added, "theimpact is substantial." (https://bit.ly/3aUZhuy)

Bone marrow cells travel to brain in some COVID-19 patients

Very large bone-marrow cells are showing up in the brains ofpeople who died of COVID-19, which may help explain some of theneurological problems associated with the disease, according toresearchers. The cells, called megakaryocytes, normally residein the bone marrow and make platelets for blood clotting. "Wefound that in some patients who died of COVID-19, thecapillaries - the smallest blood vessels - contained very largecells called megakaryocytes," study leader David Nauen of JohnsHopkins University told Reuters. "They are so large they couldbe occluding blood flow through the capillaries and limitingoxygen delivery to the brain, which could impair brainfunction." As reported on Friday in the journal JAMA Neurology,his team studied brain tissue from 15 patients who died ofCOVID-19 and found megakaryocytes in five of their brains. "Whatsignaled these cells to leave the bone marrow and travel to thebrain is unknown, but COVID-19 causes disruptions of theclotting system, and it's possible this is related," Nauen said.

Open https://tmsnrt.rs/3c7R3Bl in an external browser for aReuters graphic on vaccines in development.

(Reporting by Nancy Lapid; Editing by Will Dunham)