We write as Minnesota parents and physicians, regarding the 2021-22 school year and the masking policies of our public schools. We urge Gov. Tim Walz, state officials and school superintendents to enforce a universal masking policy in our schools for all children and campuses this fall and winter as advised by the American Academy of Pediatrics, the Centers for Disease Control and the Minnesota Department of Health.

Studies show that the delta variant of COVID-19 is quickly becoming the dominant strain among the unvaccinated — leading to what experts are now calling a "pandemic of the unvaccinated." Further, there are a number of documented breakthrough cases among vaccinated individuals that lead to transmissible disease. Given that children under age 12 do not yet have access to vaccines, it may soon become a pandemic of children.

Delta's reproduction rate and transmissibility have increased the efficiency of the virus spread. Simply being in close proximity (2 feet or less) to an infected person for five to 10 seconds can be enough to transmit the disease, and we now know that the delta variant is as contagious as chickenpox. If we fail to enforce universal masking policies in schools that serve children under 12, we risk a massive rise in the prevalence of COVID in our community.

Former FDA Commissioner Scott Gottlieb has warned that our schools and children may become "a focal point of spread" and has emphasized the importance of masking until all children have access to a COVID-19 vaccine. Per the CDC, "Masks should be worn indoors by all individuals (age 2 and older) who are not fully vaccinated. Consistent and correct mask use by people who are not fully vaccinated is especially important indoors and in crowded settings, when physical distancing cannot be maintained." The CDC has gone on to say that, given the prevalence of the delta variant, everyone should mask indoors in areas of high incidence of the virus.

We know some institutions plan to use an "honor system" — allowing people to forgo masks without checking vaccination status. Unfortunately, given the politicization of this public health crisis, the potential of asymptomatic spread by vaccinated individuals, and the inability to adequately distance in our classrooms, it is clear that relying on students/staff to mask voluntarily is not an effective means of mitigating the spread of COVID-19. Other institutions may choose to limit mask requirements to the unvaccinated. But this is an ever-evolving situation, and we are now aware that the delta variant can be both acquired and spread by vaccinated individuals. We must return to universal masking indoors if we are to contain this more contagious version of COVID-19.

We have learned a great deal since the first weeks and months of the pandemic. One lesson is that hospitalization and fatality rates are only part of the COVID story. Long COVID is characterized by an array of sometimes disabling symptoms weeks and months after initial infection. According to one study, of children ages 6 to 11 who have tested positive for COVID, 12.9% go on to develop long COVID at five weeks after infection. Among children ages 12 to 16, 14.5% develop long COVID. The costs of long COVID among children are both social and financial. But these costs are not inevitable; we can prevent them. Those 12 and older must get vaccinated and we must maintain universal masking in our schools until all children have access to a vaccine.

Another consequence of COVID-19 is the emergence of multi-system inflammatory syndrome in children, predominantly those between the ages of 3 and 12. MIS-C is a medical emergency and is characterized by the clinical and laboratory finding of severe inflammation of more than two organ systems. High-dose steroids are required for treatment and, for some children, the adrenal insufficiency that results from long-term, high-dose steroids can be life-altering.

At this time, 97 children in the state have been diagnosed with MIS-C, and 114,420 children, 19 and under, have tested positive for COVID-19. Each of these children represents multiple missed school days, missed activities, classroom closures and quarantined family members who have missed work or lost income. Universal masking isn't just about protecting the masked individual — it's about protecting our entire community.

Our children should not be forced to risk unnecessary exposure at school because of the unwillingness of adults to protect them through vaccination and mask wearing. Universal masking in our schools will be essential this fall if we wish to end this "pandemic of the unvaccinated." For the common good, for our children, for our future, keep masks in place, follow the recommendations of MDH, the CDC, the AAP and the World Health Organization, and get vaccinated.

Lona Caires is a physician in Minneapolis. This statement was submitted on behalf of 71 Minnesota physicians who also are parents.