CDC’s new Covid-19 guidelines face initial testing

In late February, the CDC monitored the Covid-19 surge and made major changes to its recommendations to address it.Well, the US case is once again On an upward trend, These recommendations face initial testing. But how can you tell if they are working?

The CDC was used to prioritize cases and positive tests to determine the threat level of Covid-19. Since February, agencies have placed greater emphasis on hospitalization.The movement has invited a lot ScrutinyAnd it reflects a change in the CDC’s pandemic response goals: Authorities are moving away from trying to eliminate the spread of the virus and reducing death and health care tensions.

The difficult truth that some public health experts have told Vox is that it will be difficult to determine if they are effective.

It will be difficult to prove that the CDC framework is credible, even in the best-case scenario where the institution follows the guidelines and the latest wave recedes.

“I know for sure if it will fail,” he said. Jeremy Faust, Boston emergency physician and health policy expert. The guidelines face the same challenges that many public health initiatives do. Failures are easier to find than successes.

As you have A new wave beginsIt is worth setting some expectations about what these guidelines can reasonably do, and how easy or difficult it is to measure their success. Ultimately, you may not know how well the guidelines work. Even if the guidelines work, the CDC may not be credible.

Why the new CDC guidelines have changed, and why experts like them

During the first two years of a pandemic, there were two key indicators for determining the severity of a pandemic. The number of cases and the test are positive.

The number of cases was determined by summing up the positive results of PCR tests performed over a specific period of time. Test positives were then determined by calculating the percentage of positive PCR tests. Together, they provided a high-level, real-time overview of the Covid-19 threat. It was used by public health agencies and agencies to guide the deployment of test programs, mask and vaccine requirements, and other public health measures.

As long as the PCR test remains much more accessible than the home test, this approach makes sense.But the test at home More widely available In the second half of 2021.To report the results of those tests Not required The method of reporting PCR test results is that PCR results are increasingly less representative of actual play conditions.

The surge in home testing has made the CDC’s key indicator “almost functionally meaningless.” Jennifer Nuzzo, An epidemiologist and pandemic specialist at Brown University’s Public Health School. And Nuzzo explained that the CDC needs to find a new way to measure the temperature of a pandemic in real time.

The February guidelines do just that, New way Estimate the burden of Covid-19 in each county. The calculations are still partially based on the percentage of new cases in the past week, but are now primarily based on the number of new hospitalizations with Covid-19 and the percentage of beds occupied by Covid-19 patients. For this reason, the CDC assigns each county a “low,” “medium,” or “high” level of burden.

CDC

The guidelines, at each level, provide a set of recommendations for facilities and the public health sector, as well as individual recommendations for individuals. Recommendation details range from low-end testing and access to vaccines to high-end backup medical staff calls.

some people Barked At the time of change, hospitalization is an indicator of delayed transmission intensity, so it increases 1-2 weeks after the number of cases increases. However, the model used to develop the guidelines deliberately set hospitalization thresholds at a level that would take weeks for the facility to prepare for increased mortality, taking into account the delay.

It also reflects the new framework CDC pandemic goal changes.. Agencies no longer focus on eliminating transmissions. Instead, it aims to use vaccines, treatments, and preventative strategies to prevent serious illness and death, minimize the burden on the healthcare system, and protect vulnerable people. The new estimate achieves this by focusing on metrics that actually quantify key indicators of health system tension and setting public health authorities to sound alarms fast enough to take action. Helps to do.

CDC

Many public health professionals feel the need for a shift, reported by organizations representing state, local, and county health authorities. Wide range of support for changes In their membership.

“Currently, it makes a lot of sense to focus on hospitalization,” he said. Justin Wrestler, Professor of Epidemiology at the University of North Carolina School of Public Health. He predicts that as the population’s immunity increases, the severity of each wave will decrease and the number of cases will become less relevant. The number of cases is doing an increasingly bad job in predicting hospitalization and death, so there is less incentive to focus on them.

“We want to prevent infection, but it’s the most difficult game of Whac-A-Mole,” Nuzzo said. But we can prevent serious illness and death, “you can prevent the hospital from being overwhelmed. It’s absolutely important,” she said.

How to know if a guideline is failing

Currently, the CDC’s US outbreak severity map shows most counties in green, indicating less burden on the community due to infection.

However, during the last month, a few counties turned yellow or orange, indicating medium or high Covid-19 levels. These color changes should make changes to public health authorities, such as strengthening testing programs for asymptomatic people and limiting visits in high-risk environments such as nursing homes and prisons. The purpose is to encourage. Mask requirements are also on the menu, Nuzzo said.

The timing here is important. Color changes are intended to be done early enough to trigger policy changes in time to prevent hospital bed shortages.

Here we could see clear signs if the guidelines failed.

If the county changes from green to orange, you need time to flatten the curve before it puts a heavy burden on resources. “If the hospital overflows and the CDC mask threshold is not met, that is simple and indisputable evidence. [the guidelines] I couldn’t achieve my goal, “Faust said.

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Other hazard signals include signs that state and local public health authorities and policy makers are not using indicators in decision making. This includes a lack of resources in the health sector, burnout of key personnel, lack of confidence in the CDC method, or inadequate political will to implement the changes suggested by the guidelines according to indicators. It may indicate a problem.

After all, the CDC guidelines are credible, but not a requirement. Ultimately, state and local governments can do what they want.

“I think we need to test it, not necessarily the metrics, but we choose how to respond to the changes in the metrics,” says Nuzzo. “That’s a wildcard.”

Why it’s difficult to detect the success of a guideline

To determine if a guideline plays that role, you first need to define what it means for it to succeed. This is currently an open issue, Wrestler said.

For the CDC recommendations to be successful, state and local public health authorities must use them as the basis for policy recommendations. Policy makers need to act on these recommendations. People and institutions need to follow those recommendations. Recommendations should have the desired effect of reducing infections and increasing access to vaccination and treatment.

However, knowing where the guidelines are implemented and where they are not is a challenge for the decentralization of our public health system. Covid-19 policy Tracker If present, different details and different policy implementations prevent the link between mitigation efforts and outcomes. There are 3,006 counties in the United States, and it is difficult to track the policies in force in all counties.

“One of the discussions about various public health systems is that it becomes a laboratory, but that is only true if there is some kind of central tracking and appropriate reporting of what is actually being tried. In a sense, the new CDC guidelines are experiments where the results cannot be combined in one place.

Spencer Pratt / Getty Images

Another annoying problem in assessing the success of guidelines is doing what individuals across the country find most reasonable to them, regardless of local policy. It’s not necessarily a sign of anarchy. The CDC guidelines actually recommend that people use government agency-sponsored indicators to guide their individual choices.

However, individual actions tend to occur in the second half of the surge, only when things are clearly really bad. Joshua Salomon, Professor of Health Policy, Stanford University. For example, people in a county full of hospitals may choose to wear a mask, even if the governor has banned the obligation to wear a mask. Such large-scale actions change outcomes and make it even more difficult to link those outcomes to policy.

If the wave of BA.2 is small, it will be difficult to know if the guidelines are working.

There is another major challenge in evaluating the new guidelines. If the Covid-19’s fast-growing BA.2 omicron subvariety wave is small, the guidelines may not face any major tests.

Cases are on the rise in the United States, and hospitalizations are increasing, albeit much more, in some northeastern states. Slower From during the explosive winter Omicron BA.1 wave. The slowdown in the spread of BA.2 (so far) can be due to a large number of people who retain some immunity after infection during their early waves.

If BA.2 does not cause a massive outbreak in the United States, “it’s a welcome surprise,” Salomon said, but “it’s not necessarily a test of new community guidance.” Our healthcare system is not threatened by a surge that does not occur, nor can we test the CDC guidelines.

Of course, if a variant worse than BA.2 appears, a big test may be imminent.

Even if the CDC guidelines help prevent dire consequences, people may see that there is no catastrophe, not as evidence that the guidelines worked, but as evidence that the guidelines were unnecessary. These situations are as confusing as when people trust public health policies for the good results that would have happened anyway.

“Even if the CDC throws a mask mandate and things seem to improve, it’s a correlation, not a causal one,” Faust said. “It will be really difficult to make fun of.