By Stan Deresinski, MD, FACP, FIDSA

Clinical Professor of Medicine, Stanford University

Dr. Deresinski reports no financial relationships relevant to this field of study.

SYNOPSIS: A high rate of COVID-19 occurred as the result of an outbreak in spring breakers. Rapid recognition and intervention, as well as the youth and good health of those infected, was effective in limiting the adverse consequences.

SOURCE: Lewis M, Sanchez R, Auerbach S, et al. COVID-19 outbreak among college students after a spring break trip to Mexico — Austin, Texas, March 26-April 5, 2020. MMWR Morb Mortal Wkly Rep 2020;69:830-835.

The COVID-19 Center at the University of Texas at Austin recognized the possibility of a COVID-19 outbreak on March 28, 2020, after becoming aware of just three confirmed infections in symptomatic students. Contact tracing, initiated on the same day, identified a spring break trip to Cabo San Lucas, Mexico, during March 14-19, as the likely initial transmission event. The center rapidly trained medical and public health students, as well as clinical and research staff members, to extend contact tracing. After reaching travelers to Cabo San Lucas and their known contacts by text, they conducted phone interviews and offered SARS-CoV-2 testing to symptomatic testing individuals (testing was limited by availability) and asked them to self-isolate until test results were reported to be negative or, if positive, to follow Centers for Disease Control and Prevention (CDC) isolation recommendations. Asymptomatic travelers and contacts were advised to monitor symptoms and to self-quarantine for 14 days.

Of the 231 subjects tested, 64 (28%) had positive results, including 60 of 183 (33%) travelers to Cabo San Lucas. In addition, one of 13 (8%) household contacts of travelers and three of 35 (9%) community contacts of travelers also had positive tests. Of the 64 with positive tests, 14 (22%) were asymptomatic at the time of testing and only six (11%) reported fever. Half of those with negative tests reported symptoms; 9% had fever. Nonetheless, the presence of symptoms was associated with a greater risk of having a positive test than was being asymptomatic (odds ratio [OR] = 3.5; 95% confidence interval [CI], 1.8 to 7.4), although no particular grouping of symptoms was diagnostic of COVID-19.

These results are enlightening, although as pointed out by the authors, a number of restraints may have affected their accurate rendering of the outbreak. Among these was an incomplete knowledge of the clinical performance characteristics of the commercial polymerase chain reaction (PCR) test that was used, which, however, has an analytic sensitivity (think “spiked” samples) of 95% in detecting 48 viral RNA copies. Another was the fact that testing could be performed only once because of supply shortages.

The foresight of the University of Texas at Austin to have in a place a COVID-19 center is to be commended, as is their rapid recognition of an outbreak and just as rapid deployment of resources to attack it with delegated authority from the public health department. (See Figure 1.) Their ability to rapidly train and deploy individuals for contact tracing also was remarkable. Their swift action undoubtedly limited the number of cases of infection that would have occurred in its absence. As a result, the consequences of this outbreak were limited.

However, other factors also were at play in limiting the damage. None of the 64 infected subjects were hospitalized and none died, having been spared by youth and previous good health.

Figure 1: COVID-19 Cases (n = 64) Following a Spring Break Trip to Cabo San Lucas, Mexico, by Exposure Source and Date of Symptom Onset,* and Public Health Investigation — Austin, Texas, March 12 – April 5, 2020

COVID-19 chart

Abbreviations COVID-19 = coronavirus disease 2019; UT = University of Texas.

* For asymptomatic cases, date of testing is used as a proxy for date of symptom onset.

Source: Lewis M, Sanchez R, Auerbach S, et al. COVID-19 outbreak among college students after a spring break trip to Mexico — Austin, Texas, March 26-April 5, 2020. MMWR Morb Mortal Wkly Rep 2020;69:830-835.

Thus, among those tested, the median age was only 22 years (range, 19-62 years), and only 15 (8%) had an underlying medical condition. Fortunately, older adults do not often have the same spring break rituals.