Sheldon Jacobson: We need clear and sensible information about when to wear a face mask – Chicago Tribune

The CDC guidelines on community risk (which effectively provides guidance on when to wear a face mask in public venues) focuses on new infection rates, hospitalization admissions, and hospital bed availability, making them reactive. The current uptick of infections with the new omicron variant, BA.2, has been slow to produce many severe cases. This means that around 90% of counties are labeled low risk, with under 1% of counties labeled high risk.

In contrast, the now challenged federal transportation face mask mandate, following a federal judge ruling, was proactive, designed to reduce the risk of virus transmission.


Some communities have strayed from the Centers for Disease Control and Prevention guidelines, adopting citywide mandates. Philadelphia is reinstating a face mask mandate in public places, even though by CDC guidelines, they are categorized as low risk. Their decision is based on the recent uptick in the rate of new infections alone, differing from the broader CDC guidelines.

Given what appears to be conflicting policies and guidelines, who are face masks protecting?


Groups who are most vulnerable to the worst outcomes of COVID-19 are those who are immunocompromised, those with multiple underlying health conditions, and those over 65 years old.

The immunocompromised are those who have health conditions that make their immune system less able to mount a sufficient response to a virus, even after they have been vaccinated. Those with multiple underlying health conditions that weaken their immune systems are also more vulnerable to severe outcomes with COVID-19.

All such people are wise to use NIOSH-approved N95 face masks, particularly in indoor public areas or in crowds, to reduce their risk of becoming infected, since infection for them is more likely to lead to hospitalization, ICU admission, and even death.

Those over 65 years old are another group that have borne the worst outcomes of COVID-19. Early in the pandemic, prior to the availability of vaccines, they were the dominant group that died from the virus. People who lived in nursing homes and assisted living facilities were highly vulnerable to the most severe outcomes of the virus.

Regardless of face mask mandates, these higher-risk groups are wise to continue to wear N95 face masks when in indoor venues and public places, particularly if the ventilation is not of the highest quality.

What about everyone else?

It depends on what each person is attempting to achieve.

If a person’s goal is to avoid infection and to limit the spread of the virus, then being fully vaccinated and boosted, and wearing N95 face masks in appropriate public venues is prudent.


If a person is willing to accept the risk of becoming infected, based on their low risk of severe outcomes, then wearing a face mask is likely not what they will choose to do.

As has already been observed from the many variants over the past two years, the virus’ propensity for mutations means that immunity against one variant may not provide complete immunity against a future variant, though thus far protection against severe disease appears to remain robust. This means that herd immunity is likely off the table in the short term, and possibly even for the foreseeable future.

Anything that can be done to reduce the risk of poor outcomes becomes more critical in an aging population. The development of safe and effective treatments remains a top priority, because people will continue to become infected and reinfected.

A low CDC community risk rating is an indicator that the COVID-19 cases in a community are not negatively affecting the community’s health care infrastructure. It however says little about the risk of virus transmission and the risk to individuals.

What all this means is that a person’s choice to wear or not wear a face mask depends on their goals. The CDC’s reactive guidelines are too coarse to be informative and provide meaningful information for most people. Advising people to seek guidance from their physician is unrealistic.

With varying personal goals across the population, a one-size-fits-all approach to face mask guidelines quickly becomes confusing. Perhaps what is needed are clear and sensible information for when and where to wear a face mask, communicated from the county level, that reduces conflict and promotes better adherence and cooperation.


Sheldon Jacobson is a professor of computer science at the University of Illinois at Urbana-Champaign.

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