Virginia Tech-led researchers to investigate the transmission of flu in child care settings

In January, the Centers for Disease Control and Prevention (CDC) updated its guidance for reducing SARS-CoV-2 (COVID-19) transmission in schools and day care settings.

But the increased focus on minimizing the spread of COVID-19 hasn't stopped the need for research on other respiratory illnesses, such as influenza virus (flu) and respiratory syncytial virus (RSV), which are also known to spread in child care settings. According to the CDC, the flu infects 9 million to 41 million people in the United States each year and leads to the hospitalization of 7,000 to 26,000 children.

Linsey Marr, the Charles P. Lunsford Professor in Civil and Environmental Engineering, is leading a team of researchers from the University of Michigan, the University of Pittsburgh, Emory University, and Georgetown University to investigate the transmission of flu in child care settings.

Their project, MITIGATE FLU, which stands for Multidisciplinary InvesTIGation to Ease inFLUenza, received $8.8 million in funding from a grant through Flu Lab, an organization that supports bold approaches to defeat influenza. Marr said the team hopes to understand how behavioral and environmental factors affect transmission rates and identify the most effective interventions.

We know a lot about the structure of the flu virus and what happens to it in the body, but we still don't have good answers to basic questions about transmission, like, 'How much is transmitted by breathing in aerosols versus touching a contaminated surface?' and 'Why is it seasonal?Some of these same questions have also been raised about COVID-19."

Linsey Marr, Charles P. Lunsford Professor in Civil and Environmental Engineering, Virginia Tech

The team has divided its research into three distinct, but related, projects. The first project focuses on improving the detection of the flu in an indoor environment. Currently, the flu virus collection and detection methods are limited by poor particle recoveries and inconsistent results from sample to sample.

"Our goal is to innovate flu virus detection in these indoor settings to help us understand when children are exposed to the viruses and how many viruses they are exposed to," said project lead Krista Wigginton, associate professor of civil and environmental engineering at the University of Michigan.

To do this, the team will develop a robot that collects samples in a classroom via interactions with children. Researchers also will develop new methods for differentiating flu viruses that are infectious versus non-infectious.

"Combined, these innovations in detection approaches will provide insight into the amount of infectious viruses present within the indoor environment in close proximity to children," said Wigginton. "This will aid in the development of interventions that reduce the amount of infectious viruses in the air."

The second project, led by Seema Lakdawala at the University of Pittsburgh and Anice Lowen at Emory University, examines the efficiency of virus transmission modes, including aerosols, droplets, and contaminated surfaces, by using ferrets and engineered viruses. Further research will determine what non-pharmaceutical interventions are most effective for blocking each transmission mode.

"Our goal is to create a new way to study the transmission of respiratory viruses that better mimics human settings and behaviors," said Lakdawala. "We hope to translate observations from animals to child care centers during outbreaks of respiratory viruses including flu and coronaviruses to block the continuing spread of viruses among kids and to our communities."

Conventional animal model systems have not been effective at clearly differentiating among transmission routes. Therefore, the team's engineering and aerosol experts have built a new system that incorporates tunable environmental parameters, ventilation rates, and detection sensors.

Marr and Lakdawala have found in previous studies that the flu virus survives in aerosols across a wide range of ambient humidity. This project will extend those findings to ferrets by exploring the effects of humidity and temperature on modes of transmission. Researchers also will test interventions, such as humidifiers, air purifiers, ventilation rates, and simple engineering barriers, that could ultimately be translated to child care settings.

The third project focuses on environmental factors driving flu transmission in child care settings. According to Andrew Hashikawa at the University of Michigan, who co-leads this project with Emily Martin, children attending group child care are known to have high rates of acute respiratory illness due to their naïve immune systems. Their high susceptibility to infection makes these child care centers an important setting in which to evaluate respiratory illness-reducing interventions.

The team will leverage the Michigan Child Care Related Infections Surveillance Program (MCRISP), an ongoing illness surveillance network of regional childcare centers in the state of Michigan, and the Michigan Household Influenza Vaccine Evaluation study (HIVE), which works with families to conduct ongoing active surveillance of viruses in the community.

"We have shown that respiratory infections spread between children in child care centers, and these infections have major impacts on families," said Martin, an associate professor of epidemiology at Michigan's School of Public Health. "We believe that by developing interventions for the child care environment, we can reduce this transmission."

By studying the presence and quantity of virus detected on surfaces and in ambient air, the research team will compare classrooms with portable air cleaners, humidifiers, or improved ventilation to those without.

"These three projects are strongly synergistic and will hopefully allow us to make a big leap in understanding transmission of the flu and how to reduce it," said Marr. "Ultimately, we hope to reduce the impact of flu on human health and associated economic costs."

With this goal in mind, the MITIGATE FLU team will not only push forward strategies to stop the spread of flu each year but also provide a framework for the study of other respiratory viruses, such as RSV and coronaviruses.