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.
Neanderthal genes linked with severe Covid-19
A group of genes passed down from extinct human cousins is linked with a higher risk for severe Covid-19, researchers say. When they compared the genetic profiles of about 3,200 hospitalized Covid-19 patients and nearly 900,000 people from the general population, they found that a cluster of genes on chromosome 3 inherited from Neanderthals who lived more than 50,000 years ago is linked with 60% higher odds of needing hospitalization. People with Covid-19 who inherited this gene cluster are also more likely to need artificial breathing assistance, coauthor Hugo Zeberg of the Max Planck Institute for Evolutionary Anthropology said in a news release. The prevalence of these genes varies widely, according to a report published on Wednesday in Nature. In South Asia, roughly 30% of people have them, compared to roughly one in six Europeans. They are almost non-existent in Africa and East Asia. While the study cannot explain why these particular genes confer a higher risk, the authors conclude, "with respect to the current pandemic, it is clear that gene flow from Neanderthals has tragic consequences."
Mosquitoes cannot transmit Covid-19
A mosquito that bites a person with Covid-19 cannot pass the coronavirus infection to its next victim, according to a study by researchers from US Department of Agriculture and Kansas State University. Mosquitoes are notorious disease carriers, transmitting West Nile virus, Zika, and many other viruses from person to person and among animals. In laboratory experiments, researchers allowed several species of disease-carrying mosquitoes, plus some other biting insects, to feed on blood spiked with the novel coronavirus, SARS-CoV-2. The virus was unable to survive and replicate itself in any of the insects, they reported in a paper posted on Wednesday on bioRxiv ahead of peer review. "Biting insects do not pose a risk for transmission of SARS-CoV-2 to humans or animals," the researchers said.
Moderna vaccine passes safety test in older patients
Results from an early safety study of Moderna Inc's coronavirus vaccine candidate in older adults showed that it produced immune responses at levels similar to those seen in younger adults, with side effects roughly on par with high-dose flu shots, researchers reported on Tuesday in The New England Journal of Medicine.
The findings are reassuring because immunity tends to weaken with age, coauthor Dr Evan Anderson of Emory University in Atlanta told Reuters. The trial involved 20 adults aged 56 to 70 and another 20 aged 71 and older. Side effects included headache, fatigue, body aches, chills and injection site pain. In most cases, these were mild to moderate. "This is similar to what a lot of older adults are going to experience with the high dose influenza vaccine," Anderson said. Moderna is already testing the vaccine in a large Phase III trial, the final stage before seeking emergency authorization or approval.
Hydroxychloroquine fails to prevent Covid-19
A malaria drug taken by US President Donald Trump to prevent Covid-19 did not help prevent coronavirus infections in healthcare workers in a gold-standard randomized controlled trial conducted at the University of Pennsylvania. The new research, published on Wednesday in JAMA Internal Medicine, shows that routine use of the drug, hydroxychloroquine, cannot be recommended to healthcare workers for prevention of Covid-19, researchers said. The study largely confirms results from a similar trial conducted at the University of Minnesota in which hydroxychloroquine failed to prevent infection among people exposed to the new coronavirus.
Immune differences seen in children with inflammatory syndrome after Covid-19
A new study may shed light on why some youngsters develop the rare and dangerous multisystem inflammatory syndrome in children (MIS-C) after recovering from Covid-19 while most do not. The syndrome can cause severe inflammation of blood vessels, the heart, lungs, kidneys, and other organs. The immune system is more highly activated in children with MIS-C than in those with Covid-19, study co-author Dr. John Wherry of University of Pennsylvania Perelman School of Medicine told Reuters. However, in MIS-C patients, the activated immune system quickly settles down, and symptoms improve, often faster than during a bout with Covid-19. Wherry noted a possible connection between a specific type of activated immune cell in children with MIS-C and some of the vascular complications seen in that condition as well as in Covid-19. "The identification of an immune cell type connected to vascular symptoms may identify a new (treatment) target if approaches can be developed to target such cells," he said. The study was published on Sunday on medRxiv ahead of peer review.