Latest on Covid-19 research: From immune response to psychiatric risk and plasma therapy

As the coronavirus pandemic has affected hundreds of countries across the world, researchers are trying to find more about the viral disease and how it affects the human body.

The coronavirus disease (Covid-19) has infected more than 21 million people and killed 773,152 across the world till date even as scientists and researchers are trying to understand the viral illness and find treatments and vaccines.

A person wearing a face mask walks through Universal CityWalk Hollywood during the outbreak of the coronavirus disease (Covid-19), in Universal City, California, US. (Reuters Photo)

Sars-Cov-2, the virus that causes the coronavirus disease, has affected more than 2.7 million and 51,797 have succumbed in India.

Here is the latest on effects of the coronavirus disease:

* According to researchers, immune responses last months and possibly longer in patients with mild Covid-19. Antibodies decrease and immunity wanes soon after recovery in mildly ill patients, early reports suggested.

* However, a Chinese study last month on 349 Covid-19 patients, which has not yet undergone peer review, found similar immune response patterns at six months regardless of symptom severity. And in a study published on Saturday ahead of peer review, US researchers performed blood tests in 15 patients after mild Covid-19, looking for three signs of lasting immune responses: antibodies, so-called memory B cells, and memory T cells.

* Rodda added, according to Reuters, they support US Centers for Disease Control and Prevention advice that patients need not be retested for COVID-19 within the first three months after an infection because the findings show immune responses last three months, if not longer.

* A study at University of Oxford of more than 62,000 Covid-19 survivors has found significant risks for mental health issues. Researchers found that one in 16 patients who never had a mental illness will be diagnosed with one within three months after infection. This risk is about twice as high as expected and is even higher among patients who were sick enough to be hospitalized, study leader Maxime Taquet told Reuters.

* Taquet said that most common are anxiety disorders, but depression, insomnia, and rarely, dementia, also occur. The study, reported on Sunday on the medRxiv website ahead of peer review, also found higher-than-average Covid-19 rates in people with a previous psychiatric diagnosis. “If you experience anxiety, low mood, insomnia or memory loss after COVID-19, you should see a medical professional as there might be ways to improve these symptoms,” Taquet said to patients, according to Reuters.

* Researchers in Hong Kong, who expected viral load to correlate with smell and taste impairment, have found that viral load was not linked to the severity of these so-called olfactory and gustatory symptoms, nor with how long it takes for the sense of smell or taste to return to normal. The findings were reported in the journal Laryngoscope.

* The findings are based on data from 39 patients in Hong Kong who developed problems smelling or tasting - or both. On average, it took 10 days for these senses to return. Four to six weeks after becoming ill, 72% had completely recovered the ability to smell and 83% were able to taste again. But there was no statistically significant link between viral load and severity of these symptoms or the recovery time.

* New data from a nationwide study in the US may help fine-tune the use of convalescent plasma to treating seriously ill Covid-19 patients. The therapy involves transfusion of antibody-rich blood plasma from people who have recovered from the disease.

* At 2,807 hospitals between April 4 and July 4, more than 35,000 hospitalised patients with, or at risk of, life-threatening Covid-19 respiratory problems received a transfusion of at least one unit of Covid-19 convalescent plasma.

* Roughly half the patients were in intensive care units and roughly one-quarter needed mechanical ventilators. Mortality rates were lower when plasma was given within three days of diagnosis, rather than later, the researchers found. And the more antibodies in the plasma, the lower the recipients’ risk of death.

*The research team concluded, in a report posted ahead of peer review on medRxiv, that while the study was not a gold-standard randomised trial, the findings added to evidence that “the quality and manner in which convalescent plasma is administered to patients hospitalized with COVID-19 may reduce mortality.”

(With agency inputs)