SARS-CoV-2 Variants, Explained | Prognosis: Covid UNCUT скачать в хорошем качестве

SARS-CoV-2 Variants, Explained | Prognosis: Covid UNCUT

Viruses mutate all the time, including the one, SARS-CoV-2, that’s caused the Covid-19 pandemic. Although most genetic changes are innocuous, some can make the mutant more adept at infecting cells, for example, or evading antibodies. Such “fitter” variants can outcompete other strains, so that they become the predominant source of infections. A succession of more-transmissible variants has emerged over the past year, each harboring a constellation of mutations. The most worrisome so far is the so-called delta variant. It’s become dominant in much of the world since its discovery in India in October 2020, leading to surges in cases and hospitalizations, especially in places where less than half the adult population has been fully immunized. What’s a variant? During replication, a virus often undergoes genetic changes that may create what are called variants. Some mutations weaken the virus; others may yield an advantage that enables it to proliferate. If changes produce a version with distinctly different physical characteristics, the variant may be co-termed a strain. A variant that deviates significantly from its viral ancestors may be identified as a new lineage, or branch on the evolutionary tree. In general discourse, however, the terms are often used interchangeably. What are the most worrisome ones? The World Health Organization uses “variants of concern” to signify strains that pose additional risks to global public health, “variants of interest” for those that warrant close monitoring because of their emerging risk, and “alerts for further monitoring” for a variant that possesses genetic characteristics that indicate it may pose a future risk. As of Oct. 10, the World Health Organization had four variants of concern and two variants of interest: Alpha This variant emerged in England in September 2020 and drove a surge in cases that sent the U.K. back into lockdown in January. Other countries, particularly in Europe, followed the U.K. in reimposing movement restrictions. Alpha was previously the dominant strain in the U.S., and has been reported in at least 195 countries, according to the WHO. Beta This one, which appeared in South Africa in August 2020, led to a resurgence in Covid cases that overwhelmed southern Africa. It’s been reported in at least 145 countries. Gamma This variant, first spotted in the Amazon city of Manaus in December 2020, has contributed to a surge in cases that strained Brazil’s health system and led to oxygen shortages. A study there found gamma was associated with a higher incidence and an increased proportion of severe Covid cases among 20-to-30-year-olds, as well as among women generally. It also found the proportion of deaths was higher among people of both sexes between 20 and 59. The variant has been found in at least 99 countries. Delta This fast-spreading variant has since been found in at least 191 countries since helping to drive a large wave of Covid cases in India. It’s estimated to be 55% more transmissible than alpha and almost twice as infectious as the original strain from early 2020. That may be because those infected with the variant can have significantly more infectious viral particles in their airways compared with individuals with other strains. Those particles appear to bind more efficiently with ACE2, the enzyme on the surface of cells that the virus targets to start an infection. New delta variants have been reported in several countries including India, the U.K. and Vietnam. A strain that includes the K417N mutation - dubbed “delta plus” in India - has stoked some concern, since that genetic change is also harbored by the beta strain that’s associated with an increased risk of reinfection. Researchers in Germany said in October that delta plus doesn’t appear to be significantly more dangerous than delta. Like this video? Subscribe: https://bit.ly/3iERrup #Covid #Prognosis #Explained Bloomberg Quicktake is a global streaming news network for a new generation of leaders and professionals. Our coverage spans your whole world, from your career ambitions to your personal passions and larger societal concerns. We provide the insights you need to make sense of the trends and stories changing your business and your world. Bloomberg Quicktake: Explained brings you the context behind the headlines, helping you see the day's news through the prism of what will matter in the years ahead. Check out our partner channels Bloomberg Quicktake: Originals for original series and Bloomberg Quicktake: Now for breaking global news. Connect with us! YouTube:    / bloomberg   Breaking News on YouTube:    / bloombergquicktakenews   Twitter:   / quicktake   Facebook:   / quicktake   Instagram:   / quicktake