By Ethan Covey

This week we bring you an update of COVID-19 among different sectors. Travel during spring break likely resulted in a COVID-19 outbreak at a Chicago-area university that infected at least 158 students. Following the implementa-tion of a COVID-19 vaccination program that was not a condition of employment, 94% of COVID-19 infections at a Mississippi medical center occurred among unvaccinated health care workers. As the delta variant circulated widely in the United States, COVID-19–associated hospitalizations increased nearly five times among children and adolescents. The number of COVID-19 cases and deaths in nursing homes may have been undercounted by more than 40%.

University COVID Outbreak Caused by Spring Break Travel?

Travel during this year’s spring break likely resulted in a COVID-19 outbreak at a Chicago-area university that infected at least 158 students, according to a CDC study.

Although various COVID-19 variants were detected, most specimens were B.1.1.222, a lineage not widely detected in Chicago before or after this outbreak but prevalent in Mexico (MMWR Morb Mortal Wkly Rep 2021;70[14]:1195-1200).

“This outbreak shows how unvaccinated students traveling during a university break and the social activities that followed resulted in multiple groups of students being infected,” said Richard A. Teran, PhD, an epidemic intelligence service officer with the Chicago Department of Public Health (CDPH) and the CDC.

An initial group of 37 cases were identified by the university and reported to the CDPH on April 7. Upon further testing, a total of 158 undergraduate students were confirmed to have COVID-19. More than 70% of cases were among students who lived in on-campus dormitories; the remainder occurred in students who lived in off-campus housing.

Dr. Teran commended the university’s prompt use of effective prevention measures, such as weekly testing, isolating infected students and contact tracing, which reduced further spread.

Interviews were conducted with 88.6% of the students who tested positive, 63.6% of whom reported recent travel during spring break. Forty percent of the students reported unmasked indoor exposure to other students, including at small gatherings, meals or while studying.

Specimens were successfully analyzed from 104 of the infected students. While 63.5% of the variants were B.1.1.222, a total of nine different linages were identified, pointing to the fact that multiple, simultaneous SARS-CoV-2 virus introductions took place around the time of spring break.

Of note, the outbreak occurred prior to vaccinations being widely available. Among the cases included in the report, only 1.9% of the students with COVID-19 reported being fully vaccinated.

“Now that vaccinations are widely available to university-age students in the U.S., vaccination is a key pre-ventive measure,” Dr. Teran said. “Vaccination is the best way to protect people from COVID-19. Colleges and universities can benefit from encouraging vaccination of all students, faculty and staff members.”

Dr. Teran also noted that schools may promote a number of policies and behaviors to prevent further outbreaks. These may include encouraging unvaccinated students to avoid travel; weekly virus screening among unvaccinated students, faculty and staff members following breaks; and ensuring readily available, free vol-untary testing for all students experiencing symptoms, regardless of vaccination status.

COVID-19 Outbreak Shows Risk of Large Events When Protocols Ignored

A COVID-19 outbreak linked to a youth camp and men’s conference in Illinois resulted in at least 180 cases, and exposure of 1,127 people from at least four states and 18 counties.

COVID-19 vaccination, testing, mask wearing and social distancing measures were not required for attendees and staff at the June events, which were sponsored by the same organization (MMWR Morb Mortal Wkly Rep 2021;70[35]:1223-1227).

“These outbreaks provided evidence of the role children play in transmission and that any indoor event where a large number of people are unvaccinated and masks are not being worn can be a fire starter for one, if not more outbreaks,” Ngozi O. Ezike, MD, the director of the Illinois Department of Public Health (IDPH) told Infectious Disease Special Edition.

The IDPH and CDC were alerted regarding a cluster of COVID-19 cases following a five-day overnight church camp for people 14 to 18 years of age that took place June 13-17, and a two-day men’s conference, which was held June 18-19.
As of Aug. 13, 180 confirmed and probable cases have been identified among people who attended the events and their close contacts. Yet, experts noted that the true counts might have been higher, because full rosters of attendees and staff at the events had not been made available.

Of the identified infections, 122 were primary cases, 48% of which were in camp attendees, and 19% in conference attendees. Eighty-five percent of cases occurred in unvaccinated individuals, while 18 break-through infections were confirmed. While the delta (B.1.617.2) variant was identified in 87% of sequenced from specimens, multiple variants were recorded, suggesting that there were multiple introductions of the SARS-CoV-2 virus into the population.

The outbreak was substantial enough that Adams County, Illinois, where many of the infected individuals resided, saw a 648% jump in the average rate of cases recorded per day.

“The outbreaks occurred at a time when Illinois had the lowest COVID-19 case counts at any point during the pandemic,” Dr. Ezike said. “We learned that organizers and participants often felt that children were not likely to get severe illness, if any at all, and would not spread the infection easily to others.”

Dr. Ezike noted that more strict adherence to CDC protocols may prevent similar future outbreaks from occurring.

“When case rates decline again, we must learn from this past experience and emphasize the need for stronger understanding by organizers about the current guidance and their role participating in public health investigations,” she said.

COVID-19 Vaccinations Greatly Cut Infections Among Health Care Workers

Following the implementation of a nonmandatory COVID-19 vaccination policy, 94% of COVID-19 infections at a Mississippi medical center occurred among unvaccinated health care workers (HCWs). The study illustrates the impact that widespread vaccination has in health care settings, according to a presentation at the IDWeek 2021 virtual meeting (poster 565).

“Health care workers have been at high risk of exposure to COVID-19, not only from the community but also within the health care setting,” said Bhagyashri D. Navalkele, MD, an assistant professor in the Division of Infectious Diseases at the University of Mississippi Medical Center, in Jackson. “Studies which were performed early in the pandemic reported 6% of hospitalizations and 4% of deaths [from COVID-19] among health care workers.”

The study looked at the impact of COVID-19 vaccination on the risk for developing the disease among HCWs at the University of Mississippi Medical Center, where vaccination was not a condition of employment. That policy went into effect on Dec. 16, 2020. From Dec. 16 through April 30, 2021, 5,687 of the center’s 11,785 employees received two doses of COVID-19 vaccine, and an additional 5,855 had received one vaccination dose.

From Jan. 4 through April 30, 2021, a total of 1,329 HCWs underwent SARS-CoV-2 testing, 217 (16.3%) of whom tested positive. Among these, 204 cases (94%) were in unvaccinated staff. Seven cases occurred in partially vaccinated HCWs, and six cases among individuals who were fully vaccinated.

Although there were six cases of breakthrough infection, no facility outbreaks occurred among asymptomatic, fully vaccinated HCWs.

“In this study, we have shown that COVID vaccination indeed does decrease the risk for developing COVID infection,” Dr. Navalkele said. “HCW vaccination is extremely important to help decrease the disease burden, avoid staffing shortages and create a safe environment in health care facilities to prevent transmission to other staff and patients.”

Delta Variant Causes Massive Increase in COVID-19 Hospitalizations Among Children

From late June through mid-August 2021, with the delta variant circulating widely in the United States, COVID-19–associated hospitalizations increased nearly five times among children and adolescents, and near-ly 10 times among children 0 to 4 years of age.

In addition, the hospitalization rate among unvaccinated adolescents 12 to 17 years of age from late June to late July 2021 was 10 times higher than among fully vaccinated adolescents (MMWR Morb Mortal Wkly Rep 2021;70[36]:1255-1260).

“COVID-19–associated hospitalizations among children and adolescents rose rapidly after the delta variant became predominant in the U.S.,” said Miranda J. Delahoy, PhD, an epidemiologist with the CDC Epidemic Intelligence Service and COVID-19 Rapid Response Team. “As children and adolescents are returning to school, continuing preventive measures to reduce cases and severe outcomes associated with COVID-19 re-mains critical. This includes vaccinating everyone eligible, universal mask wearing in schools and appropri-ate mask wearing by everyone aged 2 and older in indoor spaces and child care centers.”

In addition, Dr. Delahoy said, “increasing vaccination coverage among adolescents, as well as expanding eligibility for COVID-19 vaccination to younger age groups … could reduce severe outcomes from pediatric COVID-19.”
The study focused on reporting from the Coronavirus Disease 2019 (COVID-19)-Associated Hospitalization Surveillance Network, which includes data about laboratory-confirmed COVID-19–associated hospitaliza-tions in 99 counties across 14 states.

During June 2021, weekly hospitalization rates among children 0 to 17 years of age were at their lowest in 2021 (June 12 to July 3; 0.3 per 100,000 children and adolescents each week), but as the delta variant became widespread, hospitalization rates rose weekly to a rate of 1.4 during the week ending on Aug. 14—an increase of 4.7 times. 

The numbers approached the highest weekly hospitalization rates for children (1.5), which were reported the week ending Jan. 9. The largest increases in hospitalizations were seen among the youngest Americans; the rate of 1.9 found during the week ending Aug. 14 was nearly 10 times that of the week ending June 26.

From June 20 to July 31, the rate of hospitalization among eligible, yet unvaccinated, adolescents was 0.8 per 100,000 person-weeks, compared with 0.1 among fully vaccinated adolescents.

However, while hospitalizations rose swiftly, indicators of severe disease among hospitalized children were generally similar to those seen at other stages of the pandemic.

“Severity indicators need to be closely monitored as more data become available from the period during which the delta variant has been circulating widely in the U.S.,” Dr. Delahoy told Infectious Disease Special Edition.

“Trends in COVID-19 outcomes among children will need to be monitored closely as more data on the delta variant become available,” she continued. “While data from this report suggest that indicators of severe dis-ease among hospitalized children were generally similar to those observed earlier in the pandemic, these comparisons were based on a relatively small number of hospitalized children with severe outcomes during the period of delta predominance for which data were available (June 20 to July 31, 2021).”

Dr. Delahoy also noted that surveillance data limited to hospitalized people cannot be used to assess whether increases in COVID-19–associated hospitalization rates among children and adolescents are due to increased community SARS-CoV-2 transmission or increased disease severity caused by the delta variant.

“Additional research on this topic would be helpful to understand the severity of pediatric COVID-19 cases caused by the delta variant,” she said.

COVID-19 Cases, Deaths Underreporting in Nursing Homes Substantial

The number of COVID-19 cases and deaths in nursing homes may have been undercounted by more than 40%, according to a new study.
The findings suggest that federal National Healthcare Safety Network (NHSN) data greatly understated to-tal cases and deaths in nursing homes, leading to misleading conclusions regarding the impact of the COVID-19 pandemic (JAMA Netw Open 2021;4[9]:e2122885).

“This study is the first to systematically estimate the true death and case toll of COVID-19 on nursing homes,” said Karen Shen, PhD, of the Department of Economics at Harvard University in Cambridge, Mass. “While many are aware of the late start in federal reporting, the impact of this omission is unknown, and we felt important to investigate.”

Dr. Shen and her colleagues conducted a cross-sectional study that used data gathered from U.S. nursing homes in late May 2020. Data sources included the NHSN COVID-19 Nursing Home Data, Centers for Medicare & Medicaid Services Nursing Home Compare and Provider of Services file, state health department data, Brown University’s Long Term Care: Facts on Care in the United States, and The New York Times COVID-19 Database. Data were collected from nursing homes in 20 states, and estimates of nonreporting were extrapo-lated via an algorithm.

The team determined that a mean of 43.7% of cases, and 40% of deaths that occurred before May 24, 2020, were not reported to the NHSN, meaning that more than 68,000 COVID-19 cases and 16,000 deaths in nursing homes went unrecorded.

And while these numbers may seem staggering, the authors noted that they offer only a glimpse into the likely true scope of the pandemic.

“We did not look into other long-term care facilities, for example, assisted living, which would be an important next step to quantifying the toll,” Dr. Shen added. “Our hope is that making our data public will also allow better research for researchers hoping to investigate the determinants of COVID-19 cases and deaths, especially early in the pandemic.”