ONE OF THE most disturbing of the shockingly wide range of symptoms experienced by people with COVID-19 is often described as “brain fog,” a lingering inability to think clearly that can extend to difficulty tackling even the most basic tasks of daily life. 

But the challenge of not always being able to sort things out clearly applies just as well to our whole understanding of the virus that has upended life across the globe. In a gripping new PBS “Frontline” documentary on China’s early efforts to hold back information on the novel coronavirus that first emerged there, New York Times reporter Sui-Lee Wee reflects on the difficulty — and missteps — reporting in real-time on the upheaval set in motion by a tiny pathogen with incomplete information available. It was, she said, a situation not unlike the “fog of war.” 

Almost a year after coronavirus ground many aspects of our daily routine to halt, that fog continues to cloud some of the most basic questions we face, including whether it’s safe for schools to resume in-person instruction. 

The weight of evidence — and preponderance of views offered by public health experts — is that schools are not a significant site of virus transmission and could safely reopen, even as communities continue to deal with COVID-19 cases. A new study from Wisconsin, reported last week, seemed to support that idea, finding little evidence of virus spread in 17 schools that reopened with strict precautions in place. But the education news site Chalkbeat reports that the same week saw another study from Wisconsin, which received far less attention, claiming 5,700 COVID cases in the state last fall that were linked to outbreaks in K-12 schools or childcare settings. 

In both studies, experts say, there may have been limits to the effectiveness of contact tracing used to try to determine likely sources of infection. And without extensive surveillance testing — something most states, including Massachusetts, have been slow to roll out — it was hard to rule out undetected spread of asymptomatic cases. 

The study showing more than 5,000 cases tied to school settings also didn’t specify whether cases were tied to regular school settings or other activities like sports that may be riskier. It also didn’t include information on what safety measures schools had in place, so it’s possible the risk comes mainly from inattention to basic mitigation measures like masks and distancing. The study might, therefore, not really be evidence at all that schools can’t safely reopen. 

Of course, we want more information, not less. But because our state of knowledge on many things related to the virus is far from perfect, the flood of information that is emerging can sometimes appear to be more confusing than clarifying, especially if not considered in more detail.

Similar methods that showed little evidence of in-school spread in the first study found quite a bit of spread connected to schools statewide” in the second study, says the Chalkbeat report. 

Susan Hassig, an epidemiologist at Tulane University, told Chalkbeat she thinks the evidence leans toward the view that schools can reopen safely, with the right mitigation measures in place. But she says it’s an oversimplification to say the virus can’t spread in schools.  

“It’s complicated. It’s usually not a 100 character message,” she said, something that seems true for many aspects of the pandemic.