Expect unexpected things from delta variants

This is clear: the coronavirus is becoming more contagious. Since the virus broke out in China Get a mutation It helps it spread more easily among humans. The first Alpha variant detected in the UK last year was Increased infectivity by 50% At least the first delta variant detected in India than the original version, and now in India Increased infectivity by 40% From Alpha.

But what is less certain is how the increased infectivity of the virus affects the US pandemic.The arrival of Alpha aroused concern About the new surge in spring But no one came.Percentage of alpha cases Continued to riseHowever, the total number of cases continued to decline. People were vaccinated. Alpha became dominant in the United States The case fell even further. The virus became more biologically transmitted, but it was not transmitted to more people.

There was one confusing exception that deserves attention. In April, Michigan surged in cases where experts believed it was actually fueled by Alpha. The fact that the variants gave Michigan different results shows how difficult it is to make predictions. Alpha has little effect on the vaccine, but there is a risk of mutants that slightly erode vaccine protection. Beta and gamma, I made it quiet again.Neither is causing serious case spikes Among vaccinated people.. Michael Osterholm, an infectious disease epidemiologist at the University of Minnesota, said:

Delta has received a lot of attention because it has a collection of the most annoying traits to date. It is significantly more contagious than Alpha and can cause disease in most people who have been vaccinated only once (I’m not the one who has two), And can even cause More serious illness..This is all enough to be a warning, especially since Delta is currently responsible 10 percent of US cases And rise. But like Alpha, which was suspected to be more serious, how variants work in the real world depends more than their biology. It also depends on how we (the host of the virus) behave, how many people are vaccinated, and to some extent how lucky we are.

Read: Coronavirus variants have no place to hide

All of these factors may have influenced Michigan’s alpha-related spring surge. Emily Martin, an epidemiologist at the University of Michigan, said that people in the state had returned to near-level pre-pandemic movements, according to mobile phone mobility data during that period. Alpha variants also arrived in Michigan relatively early and happened to find a way for a group of young people who were not eligible for vaccination. “It was a kind of bad timing,” Martin told me. If Alpha arrived a little later, or the vaccine arrived a little earlier, Michigan might have looked like other parts of the country where vaccination could blunt the effects of Alpha.In Competition between mutants and vaccines Vaccines have won elsewhere in the United States.

The two concepts of virus spread help explain why timing and opportunity make such a difference.First, the coronavirus spreads ExponentiallyThis means that even a slight delay in mitigation efforts can lead to dramatically different results. Second, epidemiologists said that the spread of the virus was “OverdispersionThat means that the majority of patients do not infect anyone else, but only a handful of patients can infect dozens of people. In other words, most infectious sparks do not ignite. However, occasionally a single infection can cause an early superspreader event and eventually an outbreak. “Looking from state to state, it’s like,’Well, why is this state doing well for that state?'” According to Adam Lauring, a virologist at the University of Michigan.

Much of the world has turned to the United Kingdom in predicting how variants will work. Excellent comprehensive genome monitoring program We are tracking the rise of Alpha, and now Delta. Alpha accounted for 98 percent of all COVID-19 cases in the United Kingdom at the peak of its subspecies in March. Delta has taken over since then, Almost all new cases.. It’s too early to say if the United States will follow the same trajectory.Alpha was responsible from everywhere 38 to 86 percent Of all new US cases last month, depending on the state. Nathan Grubaud, an epidemiologist at Yale University, states that this fact suggests a limit to the comparison between the two countries. “The United States is much more heterogeneous than the United Kingdom,” he told me, the geographical differences in viral diversity and vaccine intake. As for Delta, “that means some places will be more affected,” he said. And perhaps those places will be places where few people have been vaccinated.

Experts agree that vaccines are the best way to stop Delta.Data from the UK suggests that One dose of Pfizer vaccine It provides only 34% protection for variants, but 88% for two doses. However, the large strips of the United States are still struggling to get people to take every dose. A Recently Washington post analysis We have found more than 100 counties where less than 20 percent of the population is vaccinated. “No matter what the cracks in the program for vaccination of the community, that’s what Delta is trying to exploit,” Martin said.

The United States is at least well-supplied with vaccines to fill these cracks. The challenge is social.In countries where there is not enough dose to stop it, Delta A precursor to far more problems.. In a sense, it is no exaggeration to say that the ultimate impact of Delta in the United States is unpredictable.