Metrics for Phased Prevention of Coronavirus Disease 2019 Transmission for Institutions of Higher Education: 2022 and Beyond

Abstract

In the nearly 2 years since suspending in-person activities, many institutions of higher education (IHEs) have struggled with returning students, staff, and faculty to campus safely and developed robust mitigation plans, continuing or instituting surveillance testing, and codifying stringent coronavirus disease 2019 codes of conduct. Essential to return-to-campus planning is a strategy for when and how to reduce activities to slow transmission through phased prevention—a strategy for reintroducing nonpharmaceutical interventions and “metering” activities at IHEs based on the levels of community severe acute respiratory syndrome coronavirus 2 transmission and testing. In this regard, I propose a series of mitigation measures and the metrics for their implementation, color coded and categorized in phases similar to those recommended by the federal and numerous state governments to open nonessential businesses and resume in-person services, and specific where applicable to IHEs that require vaccination and those at which vaccination is optional.

More than 1000 universities in the United States (US) have announced that they will require students or employees to be vaccinated against coronavirus disease 2019 (COVID-19) [1], though the majority have not. On campuses with vaccine requirements, it is still expected that some proportion of returning students, staff, and faculty will remain unvaccinated, and many more returners remain at risk of breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Institutions of higher education (IHEs) bring together individuals of differing age groups and potential susceptibility and vaccinated at different points during the pandemic, and while students, staff, and faculty share space, it is not clear that they share the same risk or adopt similar risk behaviors. As the COVID-19 pandemic continues, potentially more infectious variants of concern become dominant, and the likelihood of SARS-CoV-2 remining endemic increases, a strategy for reintroducing nonpharmaceutical interventions and “metering” activities at IHEs is essential to better manage risk while preserving in-person instruction, research, and other essential academic, administrative, and social functions.

The Centers for Disease Control and Prevention (CDC) last issued guidance for the suspension of activities for IHEs in December of 2020 [2], and with the widespread availability of COVID-19 vaccines it is unlikely that any US university would consider again suspending operations in their entirety due to outbreak. Though the prevalence of COVID-19 has decreased significantly in the ensuing year, the potential for breakthrough infections and transmission among even among vaccinated persons has become clear as well. In March 2020 the CDC recommended IHEs consider cancellation of classes and closure of buildings and facilities when even one confirmed case has been on campus, and regardless of community transmission. At the time, the blunt instrument of suspensions was necessary to counter the novel threat posed by SARS-CoV-2; in the months since, our understanding of transmission modes, the effectiveness of community mitigation practices, and the importance of protecting the most vulnerable grew tremendously. These lessons offer valuable insight on the complexities of balancing public health priority with educational and administrative necessity. Prior to the widespread availability of vaccines, implementing “layers” of mitigation was thought to be the most effective strategy to prevent COVID-19 [3, 4]—as IHEs resume in-person activities, reconsidering layered prevention can help protect unvaccinated people from infection on campuses while at the same time minimizing the risk of breakthrough infections among the vaccinated.

PHASES AND METRICS TO MINIMIZE TRANSMISSION RISK ON CAMPUS

Table 1 describes phased prevention strategies for campus operations, based on the observation that, like other infectious diseases, the rate of transmission of SARS-CoV-2 in communities is a function of the frequency of interactions between infected and susceptible individuals [6]. While most IHEs are not geographically isolated, the structures and processes of the university environment increase the frequency and duration of interactions between individuals affiliated with the IHE. As such, community transmission within IHEs scales with population density on campuses, and reducing density and opportunities for interaction within the university communities is likely an effective means of controlling community transmission.

Table 1.

Phased Prevention Strategies for Campus Operations

Phase	Testing	Cases	Recommended Mitigation Strategy
			Vaccine-Mandatory IHE	Vaccine-Optional IHE
Blue (low)	County test positivity rate <5%	<10 new cases per 100 000 county residents in the past 7 days	Full prepandemic operations; encourage mask wearing and surveillance SARS-CoV-2 testing for unvaccinated students, staff, and faculty at least once per week
Yellow (moderate)	County test positivity rate between 5% and 8%	10–49 daily new cases per 100 000 county residents in the past 7 days	In-person instruction, double-occupancy on-campus housing, indoor dining, in-person campus activities	Face masks for in-person instruction, single-occupancy on-campus housing, limited indoor dining, in-person campus activities
Orange (substantial)	County test positivity rate between 8% and 10%	50–99 daily new cases per 100 000 county residents in the past 7 days	Face masks for in-person instruction, on-campus housing shelter in place, grab-and-go dining, limited in-person campus activities	Remote instruction, on-campus housing shelter in place, grab-and-go dining, limited in-person campus activities
Red (high)	County test positivity rate >10%	≥100 daily new cases per 100 000 county residents in the past 7 days	Remote instruction, on-campus housing shelter in place, only essential in-person campus activities allowed	Remote instruction, no on-campus housing, only essential in-person campus activities allowed

Phase initiated when either testing or case metric reached. Phase suspended when neither testing nor case metric persists. Test positivity assumes 7-day moving average, and calculated consistent with Centers for Disease Control and Prevention guidance [5].

Abbreviations: IHE, institution of higher education; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

In addition to the phased prevention strategy presented, there are several measures IHEs should consider regardless of community transmission level to minimize the risk of on-campus outbreaks. Continuing to encourage vaccination and additional or \'booster\' doses as indicated by health authorities and requiring nucleic acid amplification SARS-CoV-2 tests for any member of the campus community with symptoms of an upper respiratory infection (regardless of vaccine status) are important measures IHEs can take to slow transmission. Improving ventilation and indoor air quality [7, 8] and encouraging the use of highly filtering face masks [9] are important mitigation measures as campuses prepare for COVID-19 endemicity, and using a color-coded system would allow a return to normalcy during periods of low transmission while quickly ramping up to deal with surges in transmission as they occur [10].

ADDITIONAL METRICS FOR IHEs WITH SURVEILLANCE SARS-COV-2 TESTING

Continued surveillance SARS-CoV-2 testing of the campus community may also significantly minimize the risk of transmission on campus (especially for mild or asymptomatic cases), particularly on campuses not mandating vaccination or where a portion of the campus community will remain unvaccinated. Table 2 describes measures for individual campus activities when periodic SARS-CoV-2 testing persists. Surveillance testing may be performed for all members of the campus community, by stratified random sampling representative of the campus community, or by campus testing events. Test positivity metrics outlined below assume aggregating results of both symptomatic testing of members of the campus community (eg, performed in the campus health center) and surveillance testing where performed.

Table 2.

Measures for Individual Campus Activities

Activity	Measure	Metric
In-person instruction	Suspend in-person instruction if any of the following metrics are reached and continue suspension until rates recede beneath thresholds for 5 sustained days:	Campus test positivity rate >10% for 5 sustained days. Isolation housing reaches 60% capacity.
Indoor dining	Suspend operations of indoor dining, including retail and campus dining halls, if any of the following metrics are reached, and continue suspension until rates recede beneath thresholds for 5 sustained days:	Campus test positivity rate >5% for 5 sustained days.
On-campus housing	Initiate individual residence hall shelter-in-place if any of the following metrics are reached:	Individual residence hall test positivity rate exceeds 10% for 5 sustained days. Sustained increase in campus positive tests for 5 days.
	Initiate on-campus housing shelter-in-place if any of the following metrics are reached:	On-campus housing test positivity rate exceeds 10% for 5 sustained days. Sustained increase in on-campus housing positive tests for 5 days.
	Initiate individual residence hall move-out if any of the following metrics are reached:	Individual residence hall test positivity rate exceeds 10% for >5 sustained days. Sustained increase in campus positive tests for 10 days.
	Initiate on-campus housing move-out if any of the following metrics are reached:	Campus test positivity rate ≥10%. Isolation housing reaches 80% capacity.
In-person activities	Suspend all in-person activities if any of the following metrics are reached and continue suspension until the next academic term:	Sustained increase in campus positive tests for 15 days. Campus test positivity rate ≥25%. Daily testing capacity of the University Health Center is exceeded for 3 consecutive days.

The additional utility of campus surveillance testing is the ability to meter individual campus activities, such as in-person instruction, indoor dining, and residence hall operations, based on rates of positivity in testing on campus generally, within specific subgroups on campus, and for IHEs with students residing in university-owned housing, the availability of isolation space for SARS-CoV-2–infected students.

Finally, to ensure that all members of the campus community are cognizant of the level of risk of transmission or infection by participating in daily activities, it is recommended that the IHE develop a public dashboard of the abovementioned metrics, as well as case count by race/ethnicity, resident hall, unit, and university function.

CONCLUSIONS

The resumption of in-person instruction, on-campus housing, and campus operations has increased the risk of transmission of SARS-CoV-2 and contracting COVID-19. And, while vaccination is our best collective defense against SARS-CoV-2 outbreaks, layering defenses is more effective than any single strategy. If instituted, continued adherence to a layered mitigation strategy, the proposed metrics, and associated policies will help ensure that as many essential functions of campus as possible are able to persist while minimizing risk to both vaccinated and unvaccinated members of campus communities.

Notes

Potential conflicts of interest. The author: No reported conflicts of interest.

The author has submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.