This week's roundup of some of the latest scientific studies on the novel coronavirus and efforts to find COVID-19 vaccines centers around how the virus affects men and women differently and the reasons why in addition to the respiratory illness' ties with heart damage.
Gender differences in deaths tied to immune responses
The immune system of women may induce more appropriate responses to the coronavirus, a small study suggests, providing a clue as to why COVID-19 tends to be more severe in men. Among 98 mostly older adults, who were hospitalized with mild or moderate COVID-19, women overall had more "robust" and "sustained" attacks on the virus by their immune systems' T cells, researchers reported on Wednesday in Nature.
Poor T cell responses in men were linked with worse outcomes, they found. There were also gender differences in the production of signaling molecules – known as chemokines and cytokines – that recruit immune cells to sites of inflammation. On average, men had higher levels of these molecules, but when women did have high levels, they tended to do poorly. The findings "provide an important basis for the development of a sex-based approach to the treatment and care of men and women with COVID-19," researchers said. Men may benefit from therapies that boost their T cell responses, whereas women may benefit from therapies that dampen the signaling molecule response, they said.
Hormones may add to women’s COVID-19 survival benefit
Sex hormones may contribute to gender differences in COVID-19 mortality, new research suggests. While women have lower COVID-19 death rates than men, the difference is narrower among older men and women. Levels of the female hormone estradiol – which are naturally higher in younger women – might help explain that pattern. Researchers studied electronic health records of nearly 37,000 female COVID-19 patients from 17 countries, comparing pre- and post-menopausal women and taking into account the use of estradiol in contraceptives or hormone replacement therapy (HRT).
Birth control drugs were not linked with any significant effect on COVID-19 mortality risk. But among women over age 50, those receiving HRT with estradiol had a two-thirds lower risk of death from the coronavirus compared to non-users in that age group. The study does not prove that HRT caused a reduced risk. In their report posted on medRxiv on Monday ahead of peer review, the researchers warned that hormones can have side-effects and women should not start using them on their own. The researchers call for large prospective trials to test the theory that estradiol therapy might help lower older women's risk of death from COVID-19.
Coronavirus discovered in heart muscle cells
The new coronavirus, which has previously been detected in some heart tissues, can also invade heart muscle cells, or myocytes, researchers have found. In Brazil, doctors found the virus in cardiac myocytes of an 11-year-old with multisystem inflammatory syndrome related to COVID-19 who died of heart failure, according to a report in The Lancet Child & Adolescent Health.
In Italy, six adults who died of COVID-19 respiratory failure had active coronavirus in cardiac myocytes, with varying degrees of myocyte injury and cell death, doctors reported Wednesday on medRxiv ahead of peer review. None of the Italian patients had cardiac symptoms or a history of heart disease.
The Italian doctors point out that 40% of patients who recovered from the genetically related SARS virus outbreak in 2002-2003 later developed cardiovascular abnormalities. The new findings, they say, suggest that recovered COVID-19 patients should be monitored for heart problems even when they do not appear to be at risk, "since the cardiovascular long-term outcome of COVID-19 patients may mirror SARS patients."
Food-additive might make pandemic dental visits safer
Scientists may have a solution to a hazard faced by dentists and their patients during the coronavirus pandemic. The mists generated by water used in dentists' tools could potentially carry exhaled coronavirus particles through the air. Mixing the water with a small amount of an FDA-approved food additive called polyacrylic acid can markedly suppress these mists or even prevent them, researchers reported on Tuesday in the journal Physics of Fluid. "What was surprising is that the very first experiment in my lab completely proved the concept," coauthor Alexander Yarin of the University of Illinois at Chicago said in a news release.
"It was amazing that these materials were capable of so easily and completely suppressing aerosolization by dental tools." The spraying mist results when water encounters rapid vibration of a dental tool or the centrifugal force of a drill, which bursts water into tiny droplets and propels them into the air, the researchers explain. The polymer suppresses these bursts as large polymer molecules stretch like rubber bands, pulling the droplets back and preventing them from becoming airborne.