Is Covid more dangerous than driving? How scientists analyze Covid risks.

Like it or not, the pandemic’s pick-yourself-adventure period is upon us.

Mask mandates have fallen. Some free test sites are closed. No matter which parts of the United States were still jointly trying to quell the pandemic, they have largely turned their focus away from counseling throughout society.

Now, though the number of cases is starting to rise again and more infections are not being reported, it is up to individual Americans to decide how much risk they and their neighbors face from coronavirus – and what to do about it.

For many people, the threats from Covid have eased dramatically during the two years of the pandemic. Vaccines reduce the risk of being hospitalized or dying. Powerful new antiviral pills can help prevent vulnerable people from getting worse.

But not all Americans can count on the same protection. Millions of people with weakened immune systems do not get the full benefit of vaccines. Two-thirds of Americans, and more than a third of those 65 and older, have not received the critical security as a booster shot, with the most worrying rates among blacks and Hispanics. And patients who are poorer or live further away from doctors and pharmacies face steep barriers to getting antiviral pills.

These vulnerabilities have made the calculation of the risks of the virus a complete exercise. Federal health officials’ recent proposal that most Americans could stop wearing masks because the number of admissions was low has created confusion in some circles about whether the likelihood of becoming infected had changed, scientists said.

“We’re doing a really terrible job of communicating risk,” said Katelyn Jetelina, an epidemiologist at the University of Texas Health Science Center in Houston. ‘I think that’s also why people throw their hands up and say,’ Screw it ‘. They are desperate for some kind of guidance. “

To fill this void, researchers are rethinking how to discuss Covid risks. Some have studied when people could detect indoors if the goal was not only to prevent hospitals from being overrun, but also to protect immunocompromised people.

Others are working on tools to compare infection risks with the dangers of a wide range of activities, and find, for example, that an average unvaccinated person aged 65 and older is about as likely to die from an Omicron infection as a person dies from using heroin for a year and a half.

But how people perceive risk is subjective; no two people have the same sense of the chances of dying from half a year of heroin use (about 3 percent, according to an estimate).

And in addition, many scientists said they were also concerned that this latest phase of the pandemic would place too much of the burden on individuals to make choices to keep themselves and others safe, especially while the tools to combat Covid remained outside. reach of some Americans.

“As much as we do not want to believe it,” said Anne Sosin, who studies health at Dartmouth, “we still need a community-wide approach to the pandemic, especially to protect those who cannot take full advantage of vaccination.”

Although Covid is by far the only health threat in the United States, it is still one of the most significant. In March, even as the deaths from the first Omicron rise fell, the virus was still the third leading cause of death in the United States, only after heart disease and cancer.

More Americans have generally been dying than would have been in normal times, a sign of the virus’ wide numbers. At the end of February, 7 percent more Americans died than would have been expected based on previous years – in contrast to Western European nations such as Britain, where overall deaths have recently been lower than expected.

How much virus circulates in the population is one of the most important measures for people trying to measure their risks, scientists said. That remains true, although the number of cases now underscores true infections by a large margin because so many Americans test at home or do not test at all, they said.

Even with many cases missing, the Centers for Disease Control and Prevention now places most of the Northeast at “high” levels of viral transmission. In parts of the region, the number of cases, although much lower than in winter, is approaching the peak of the autumn Delta variant increase.

Much of the rest of the country has what the CDC describes as “moderate” levels of transmission.

The amount of circulating virus is critical because it dictates how likely it is that someone will encounter the virus and in turn roll the dice on a poor result, scientists said.

That’s part of what makes Covid so different from the flu, scientists said: The coronavirus can infect many more people at once, and with people more likely to get it, the overall chance of a bad outcome increases.

“We’ve never seen flu prevalence – how much of it is there in society – in the numbers we’ve seen with Covid,” said Lucy D’Agostino McGowan, a biostatistician at Wake Forest University.

Even two years into the pandemic, the coronavirus remains new enough and its long-term effects unpredictable enough to make measuring the threat of an infection a difficult problem, scientists said.

An unknown number of infected people will develop long-lasting Covid, leaving them severely debilitated. And the risk of getting Covid extends to others, potentially with poor health, which can therefore be exposed.

Yet, with far more immunity in the population than there once was, some epidemiologists have tried to make risk calculations more accessible by comparing the virus to everyday dangers.

The comparisons are particularly knotty in the United States: the country does not conduct the randomized trials needed to estimate infection levels, making it difficult to know what proportion of those infected die.

Dr. Jetelina, who has published a set of comparisons in her newsletter, Your Local Epidemiologist, said the exercise highlighted how difficult risk calculations remained for everyone, including epidemiologists.

For example, she estimated that the average vaccinated and boosted person who was at least 65 years old had a higher risk of dying from a Covid infection than the risk of dying during a year of military service in Afghanistan in 2011. She used a standard risk unit known as a micro-mortar, which represents a chance of one in a million to die.

But her calculations, gross as they were, included only recorded cases instead of unreported and generally milder infections. And she did not take into account the delay between cases and deaths when she looked at data from a single week in January. Each of these variables could have provided estimates of the risk.

“All of these nuances underscore how difficult it is for individuals to calculate risk,” she said. “Epidemiologists also have a challenge with that.”

For children under 5, she found, the risk of dying from a Covid infection was about the same as the risk of mothers dying during childbirth in the United States. However, this comparison highlights other difficulties in describing risk: Average figures can hide large differences between groups. For example, black women are almost three times more likely to die in childbirth than white women, which in part reflects differences in the quality of medical care and racial bias in the health care system.

Cameron Byerley, an assistant professor of mathematics education at the University of Georgia, built an online tool called Covid-Taser that allows people to adjust age, vaccine status and health background to predict the risks of the virus. Her team used estimates from earlier in the pandemic of the proportion of infections that led to poor results.

Her research has shown that people have trouble interpreting percentages, Dr. Byerley. She recalled that her 69-year-old mother-in-law was unsure if she should worry earlier in the pandemic after a news program said people her age had a 10 percent risk of dying from an infection.

Dr. Byerley suggested her mother-in-law imagine if she, once out of 10 times using the toilet on any given day, died. “Oh, 10 percent is awful,” she remembered her mother-in-law saying.

Dr. Byerley’s estimates show, for example, that an average 40-year-old vaccinated over six months ago had roughly the same chance of being admitted after an infection as a person who had to die in a car accident during 170 across the country. . road trips. (Newer vaccine shots provide better protection than older ones, complicating these predictions.)

For immunocompromised people, the risk is higher. An unvaccinated 61-year-old with an organ transplant, estimated Dr. Byerley, is three times more likely to die after an infection than a person should die within five years of receiving the diagnosis of stage one breast cancer. And the transplant recipient is twice as likely to die of Covid as a person dies while climbing Mount Everest.

With the most vulnerable people in mind, Dr. Jeremy Faust, an emergency physician at Brigham and Women’s Hospital in Boston, last month set out to determine how low the number of cases would be for people to stop wearing indoor masks without endangering those with extremely weakened immune systems. systems.

He imagined a hypothetical person who had no benefit from vaccines, wore a good mask, took hard to get prophylactic medication, attended occasional gatherings, and acted but did not work personally. He aimed to keep vulnerable people’s chances of becoming infected below 1 percent over a period of four months.

To reach this threshold, he found, the country would have to keep masking indoors until transmission dropped to less than 50 weekly cases per year. 100,000 people – a stricter limit than the CDC currently uses, but one that he said nonetheless offered a benchmark to aim for.

“If you just say, ‘We take off masks when things get better’ – that’s true, I hope – but it’s not really helpful because people do not know what ‘better’ means,” said Dr. Faust.

For people with immune deficiencies, the end of the collective effort to reduce the level of infection has been unsettling.

“All the layered protections we’ve talked about for the entire pandemic, each of them being removed,” said Marney White, a professor of public health at Yale University who is immunocompromised. She said families in her local school district urged each other not to report Covid cases. “It’s impossible to calculate risk in these situations,” she said.

Dr. Ashish K. Jha, the White House’s Covid Response Coordinator, said the administration had helped reduce people’s risks by making quick tests and masks easier to obtain and by working with clinics to quickly prescribe antiviral pills. Better communication was needed to distribute preventative medicine to immunocompromised people, he said.

“We need a system that can very easily provide therapy to them,” he said. “It’s largely the responsibility of the government.”

Preparing better for the current rise – and future ones – could make people’s risks more manageable, even if it does not eliminate them, scientists said. By ventilating indoor spaces, guaranteeing paid sick leave, delivering boosters shots to people’s doorsteps and making it easier to be treated, the government could help people make choices with less fear of disaster, they said.

“We should put infrastructure in place that allows us to respond quickly when we have the next wave,” said David Dowdy, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health.

“We should train people in that when these waves hit, there are certain things we will have to do,” he added, like imposing short-term mask mandates. “You can then live your life in respect of that opportunity – but not in fear that it could happen at any time.”

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