What’s different about the Delta variant?

 

The US has recently done an about-face on its approach to the coronavirus pandemic. Masks are back, vaccine mandates are looming, and officials are sounding more worried than they have in months.   Driving this are two things: The large number of Americans who remain unvaccinated, and the rapid spread of the Delta variant.   While we aren’t exactly sure how much more transmissible the Delta variant is, one internal CDC document indicates the Delta variant is about as transmissible as chickenpox – with each infected person infecting as many as eight or nine others, on average. The original strain of coronavirus, the CDC indicated, was about as contagious as the common cold, with each infected person infecting about two others.   We also know it may look like the Delta variant is making people sicker, but more than 90% of people showing up for treatment are unvaccinated, according to the CDC and hospital officials who have spoken to CNN.  So while people may be more likely to become infected in the first place with Delta if they are unvaccinated, there’s no hard data yet showing that Delta causes more serious disease.   A lot of the worry behind the Delta variant comes down to its mutations. Delta has at least three mutations on a structure that is called the receptor binding domain – the part of the virus that directly docks onto the human cells it infects. They may help it escape detection by the immune system, and at least one of them may help it bind more tightly to cells.   Another mutation in a place known as the furin cleavage site – it’s on the characteristic spike protein – might also help make the virus infect cells more easily, according to the American Society of Microbiology.   But as we know, the answer to stopping the spread, infectious disease experts universally say, is more vaccination. “If we have more and more people vaccinated, we will win in this race,” CDC Director Dr. Rochelle Walensky said last week.