The limits of "following the science"

Driving the news: The CDC's decision to loosen masking guidance is the latest example of a pandemic policy rooted in science, but that is ultimately a judgment call.

• The agency tied the revised guidance to an updated formula for determining a community's risk level. The change reflects the fact that vaccinations and the Omicron variant have made case counts a less useful measure of pandemic severity, and some experts say it was long overdue.
• Other experts, however, have also used science to criticize the change, arguing it fails to protect people who are immunocompromised, children who aren't eligible for vaccination or children for whom new data suggests vaccines don't adequately protect against infection.

The big picture: President Biden took office vowing to "follow the science." But science is much less of a road map than it is information that should be used to choose the best route.

• For example, science told us last summer that the vaccines' effectiveness had waned over time. But it didn't tell us what level of effectiveness was acceptable, or if and when a booster shot was needed. Policymakers and regulators had to provide those answers.
• Similarly, there is no scientific marker for when someone needs to wear a mask. This allows health experts and scientists to be able to disagree on what policy should be while still claiming that they are following the science.
• "Two different scientists can look at the same set of data and come up with different conclusions. That's not to say that one person is being unscientific or ignoring the scientific process," said Leana Wen, an emergency physician and a professor at George Washington University. "Public health policy is also a measure of values."

Between the lines: Science isn't absolute — data can come with uncertainties and unknowns.

• A clinical trial gives much more irrefutable information than modeling, for example, which relies on assumptions to make a projection.
• Sometimes decisions are made with limited available data. For example, some countries are starting to give second booster shots before we have longer-term effectiveness data on the first ones.
• Making policies led by science also involves judgement calls that account for economics, mental health, education and other facets of daily life, including what society is actually willing to do.

Even once a decision is made, policymakers and health officials can then fail to adequately communicate how they made it — including by overstating the role of science.

• The CDC's decision to reduce the recommended isolation period for people who test positive for COVID, for example, drew criticism from some experts who argued that leaving isolation after five days should be dependent on receiving a negative rapid test.
• Although the agency claimed the change was "motivated by science," its own data now shows that it's common for people to continue to continue testing positive for several days after the recommended isolation period.
• But many Americans didn't have access to rapid tests during the Omicron surge. Even more importantly, Omicron was spreading so quickly at the time that officials were worried about society being able to operate.

What they're saying: "One of the reasons it can get so confusing is that people are not clear about what are all the different factors that are going into the decision, and they just sort of gloss over it and say, 'We're following the science,'" said infectious disease specialist and KHN editor-at-large Céline Gounder.

• That risks putting scientists on the hook for policies rather than the politicians who make them, Roger Pielke of the University of Colorado, Boulder, told Axios last year.

The bottom line: The pandemic touches so many parts of society that science alone, no matter how complete a set of data is, can't be the sole determiner of policy.

• "The goal of what we're trying to do cannot simply be set by scientists, because that is a societal value," Wen said.

Go deeper: Pandemic science advise comes under scrutiny