Cold Viruses Thrived in Kids as Other Viruses Faded in 2020

The common-cold viruses rhinovirus (RV) and enterovirus (EV) continued to circulate among children during the COVID-19 pandemic while there were sharp declines in influenza, respiratory syncytial virus (RSV), and other respiratory viruses, new data indicate.

Researchers used data from the Centers for Disease Control and Prevention’s (CDC’s) New Vaccine Surveillance Network. The cases involved 37,676 children in seven geographically diverse US medical centers between December 2016 and January 2021. Patients presented to emergency departments or were hospitalized with RV, EV, and other acute respiratory viruses.

The investigators found that the percentage of children in whom RV/EV was detected from March 2020 to January 2021 was similar to the percentage during the same months in 2017–2018 and 2019–2020. However, the proportion of children infected with influenza, RSV, and other respiratory viruses combined dropped significantly in comparison to the three prior seasons.

Danielle Rankin

Danielle Rankin, MPH, lead author of the study and a doctoral candidate in pediatric infectious disease at Vanderbilt University, in Nashville, Tennessee, presented the study on September 30 during a press conference at the Infectious Disease Week (IDWeek) 2021 Annual Meeting.

Table. Comparison (%) of Children Positive for Viruses Over Four Seasons

Virus type 2017–2018 2018–2019 2019–2020 2020–2021
RV/EV 29.0 34.4 30.4 29.6
RSV 16.7 18.2 20.5 1.2
Influenza 8.4 4.7 10.5 2.6
Other respiratory viruses* 15.3 14.0 14.0 6.1
*These include human metapneumovirus, parainfluenza types 1–4, and adenovirus.


“Reasoning for rhinovirus and enterovirus circulation is unknown but may be attributed to a number of factors, such as different transmission routes or the prolonged survival of the virus on surfaces,” Rankin said. “Improved understanding of these persistent factors of RV/EV and the role of nonpharmaceutical interventions on transmission dynamics can further guide future prevention recommendations and guidelines.”

Dr Claire Midgley

Co-author Claire Midgley, PhD, an epidemiologist in the Division of Viral Diseases at the CDC, told reporters that further studies will assess why RV and EV remained during the pandemic and which virus types within the RV/EV group persisted.

“We do know that the virus can spread through secretions on people’s hands,” she said. “Washing kids’ hands regularly and trying not to touch your face where possible is a really effective way to prevent transmission,” Midgley said.

“The more we understand about all of these factors, the better we can inform prevention measures.”

Andrew T. Pavia, MD, chief, Division of Pediatric Infectious Diseases, University of Utah, Salt Lake City, Utah, who was not involved in the study, told Medscape Medical News that rhinoviruses can persist in the nose for a very long time, especially in younger children, which increases the opportunities for transmission.

“Very young children who are unable to wear masks or are unlikely to wear them well may be acting as the reservoir, allowing transmission in households,” he said. “There is also an enormous pool of diverse rhinoviruses, so past colds provide limited immunity, as everyone has found out from experience.”

Dr Martha Perry

Martha Perry, MD, associate professor at the University of North Carolina School of Medicine, Chapel Hill, North Carolina, and chief of adolescent medicine, told Medscape Medical News that some of the differences in the prevalence of viruses may be due to their seasonality.

“Times when there were more mask mandates were times when RSV and influenza are more prevalent,” said Perry, who was not involved with the study. “We were masking more intently during those times, and there was loosening of restrictions when we see more enterovirus, particularly because that tends to be more of a summer/fall virus.”

She agreed that the differences may result from the way the viruses are transmitted.

“Perhaps masks were helping with RSV and influenza, but perhaps there was not as much hand washing or cleansing as needed to prevent the spread of rhinovirus and enterovirus, because those are viruses that require a bit more hand washing,” Perry said. “They are less aerosolized and better spread with hand-to-hand contact.”

Perry added that on the flip side, “it’s really exciting that there are ways we can prevent RSV and influenza, which tend to cause more severe infection.”

Rankin said limitations of the study include the fact that from March 2020 to January 2021, healthcare-seeking behaviors may have changed because of the pandemic and that the study does not include the frequency of respiratory viruses in the outpatient setting.

The sharp 2020–2021 decline in RSV reported in the study may have reversed after many of the COVID-19 restrictions were lifted this summer.

Medscape Medical News reported in June of this year that the CDC has issued a health advisory to notify clinicians and caregivers about an increase in cases of interseasonal RSV in parts of the southern United States.

The CDC has urged broader testing for RSV among patients presenting with acute respiratory illness who test negative for SARS-CoV-2.

The study’s authors, Pavia, and Perry have disclosed no relevant financial relationships.

Infectious Disease Week (IDWeek) 2021 Annual Meeting: Abstract 154. Presented September 30, 2021.

Marcia Frellick is a freelance journalist based in Chicago. She has previously written for the Chicago Tribune and and was an editor at the Chicago Sun-Times, the Cincinnati Enquirer, and the St. Cloud (Minnesota) Times. Follow her on Twitter at @mfrellick.

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