Many U.S. school buildings, especially those operated by the public sector, were closed last year. Academic progress, child development, and psychological health suffered from e-learning. Was there an offsetting health benefit for students, teachers, or their families? If so, of what magnitude?
Economics is essential for answering these questions. Human behavior affects disease transmission and responds to incentives and economic organization. Economists have long analyzed and prepared standardized measures of occupational risks, of which contracting COVID-19 at school is a novel instance. Occupational-risk analysis particularly emphasizes the time dimension of infection risks and thereby their relationship with other health risks experienced in more familiar occupational and consumer settings.
This approach readily shows that the fatality risk to self and living partners, which may include an elderly person, for one day taught in person by the average nonelderly K–12 teacher during the fall 2020 term was comparable to the risk of driving 18 miles alone in a car.
At first glance, one might expect in-person classes to be superspreader events. We know that in-person school involves a large number of personal contacts, which is the way that infectious respiratory diseases can spread. In-person schooling appears to have contributed to the spread of previous seasonal flus.
However, economic incentives during COVID-19 are different from those during a typical flu season because COVID-19 is a more harmful disease. The prevention efforts used during COVID-19 should not be, and were not, the same during fall 2020 as they were in previous flu seasons. In schools, the fall 2020 precautions usually included face masks, restricted school entry, extra spacing, cohort arrangements, reduced class sizes, daily symptom screening, and cancellation of extracurricular activities. Because prevention efforts potentially could reduce infection risks in schools both absolutely and relative to wider community risks, additional measurement is required to assess the equilibrium infection rate a person could expect from participating in person at school.
Measuring infection risk in schools is just a special case of measuring occupational risks, which private and government economists have been doing for decades. The following estimates use data from North Carolina, Wisconsin, Australia, England, and Israel covering almost 80 million person-days of school during 2020. Especially informative are those studies (North Carolina, Wisconsin, and England) that measured not only how many students and teachers were infected, but also the source of infection (i.e., a contact made at school versus a contact made elsewhere in the community).
One result, perhaps unsurprising, is that the fraction of students and teachers getting infected at school was proportional to infection rates in the general community. This means that the occupational hazard of COVID for in-person teachers varied by community. But it also means that the hazard of COVID for remote teachers and students also varied by community. A second result is that the fatality risk varies with age. The following results refer to the average community in fall 2020, unless otherwise noted, and specific age groups.
Unlike a fatal work injury, an infection acquired at school can be transmitted to the student or teacher’s family members. I therefore used data on both household-transmission rates and the living arrangements of K–12 students and teachers to account for fatalities that would have occurred in families as a result of an infection that one of the members got at school.
The table below shows various occupational-fatality risks before the pandemic, as well as the risk to teachers during the pandemic. The riskiest occupations were the fishing and hunting occupation, in which a fatality occurs once a year for every 690 persons employed. The rate for all jobs in the economy was one out of 28,571. Government jobs were safer than average, with deaths occurring once per 55,556 person years employed in 2019. In-person teaching during the pandemic was safer still. For the most common teacher demographic — those aged 25-44 with a spouse in the same age bracket — fatalities occurred once per year per 77,547 in-person teachers. The fatalities here include fatalities to teacher and family members from school-acquired COVID as well as other teacher fatalities from injuries occurring at school.
Person-years of selected activities per fatality in that activity
|Occupation/Industry||Person-years per fatality|
|Fishing and hunting workers||690|
|Aircraft pilots and flight engineers||1,618|
|Driver/sales workers and truck drivers||3,731|
|Educational and health services||125,000|
|Professional and related occupations||142,857|
|Addendum: Fall 2020 modal in-person teacher||77,547|
For every 22 million unvaccinated students and teachers schooling in person for a five-day week, the expected number of fatalities from school-acquired COVID-19 among teachers and spouses is one or fewer. Note that 22 million people distanced six feet apart would form a line that covers the entire Earth’s equator and overlap itself again for 2,700 miles.
These results show that the COVID risks of teaching in person are well within the range of familiar occupational risks that are priced in the labor market at about $10 million per expected fatality. Using that price, the cost of teaching a day in person (in fall 2020, before any vaccine was available) compared with spending the day in a zero-risk environment ranged from less than a penny per day for a young teacher living alone in a low-prevalence community to $29 per day for an elderly teacher living with an elderly adult in a high-prevalence community.
The risk to teachers of dying from COVID acquired at school were also similar to risks familiar to us as consumers. For example, driving an automobile 18 miles per school day would have about the same fatality risk as teaching in person in fall 2020. Few of us view mortality as a major cost of taking such a drive.
Furthermore, the alternatives to being in school were not risk free. Rarely did students and staff sent home from school go into solitary confinement where they would not be infected or infect others. Students and teachers at in-person schools during 2020 were about 20 times more likely to be infected outside school than in school. On an hourly basis, the schools were more than four times as safe as the places frequented by students and staff when not in school.
A couple of factors combined to make teaching in person comparatively safe. One is that schools did a good job of keeping infectious teachers and students at home on the days they were sick. Occasionally infectious students and teachers did attend school, but when they arrived the school’s portfolio of ventilation, distancing, masking, cohorting, and other policies resulted in very low rates of transmission to anyone else in the school.
The fall 2021 school term is proceeding under different disease conditions, especially regarding teacher vaccinations, community prevalence, and other components of school prevention. Teachers have had almost a year to receive COVID-19 vaccines, which (depending on the virus variant) have been about 90 percent effective in preventing disease, which by itself reduces teacher fatalities by a factor of ten. Prevalence may prove to be lower on average in fall 2021 than in fall 2020. On the other hand, under these conditions, schools will have less of an incentive to maintain other costly prevention efforts such as screening and cancellation of extracurricular activities. I estimate that eliminating all screening could by itself increase transmission by a factor of up to three. Even if relaxing the other prevention efforts increased the other components of in-school transmission by a factor of ten, the fatality cost of each day of in-person teaching during the 2021-2022 school year would still be no more than it was during 2020, which itself was both dwarfed by the other costs of schooling and small enough to challenge comprehension.