Unlike flu, cold viruses persisted during pandemic, study finds

Unlike influenza and respiratory syncytial virus, which all but disappeared during their typical winter peaks, common cold viruses continued to circulate among children during the COVID-19 pandemic, according to researchers at IDWeek.

Natasha B. Halasa, MD, MPH, the Craig Weaver Professor of Pediatrics at Vanderbilt University Medical Center, described the seven sites participating in the CDC’s New Vaccine Surveillance Network (NVSN), which included pediatric hospitals in Seattle, Houston, Kansas City, Cincinnati, Pittsburgh, Rochester and Nashville.

Halasa and colleagues used data from the NVSN to detect viruses circulating before and during the pandemic. The surveillance network “includes study sites that focus on population-based surveillance and data collection on the use and impact of vaccines and the impact of vaccine policies,” according to the CDC.

“The uniqueness of the surveillance system is that it’s active, prospective and multicenter,” Halasa said during a press conference announcing the group’s findings. “In addition, since it’s ongoing, the platform is ready to detect and determine the burden of emerging viruses like SARS-CoV-2. Therefore, because the surveillance occurred year-round, we were able to compare the burden of viruses before and after the pandemic.”

The study enrolled 37,676 children who were tested for respiratory viruses, including 4,691 who were enrolled and tested from March 2020 to January 2021, during the pandemic.

During that period, the percentage of enrolled children who tested positive for rhinovirus/enterovirus (RV/EV) — around 30% — was similar compared with the same time period in 2017-2018 and 2019-2020, while the incidence of RSV, influenza and other respiratory viruses declined, the researcher reported.

For example, the proportion of children who tested positive for RSV or influenza declined from 20.5% and 10.5% in 2019-2020 to 1.2% and 2.6% during the pandemic, respectively.

CDC epidemiologist Claire Midgley, PhD, said “it’s not completely clear” why RVs/EVs persisted during the pandemic — or even how they are transmitted, although some evidence suggests they may use multiple pathways, making it harder to block transmission. She said the viruses are known to spread via secretions on hands.

“More work is needed to understand some of the mechanisms behind why RVs/EVs persisted when some other viruses didn’t,” Midgley, who was involved with the research, said during the press conference. “We do have some idea that it might be because RVs/EVs are very small, very stable viruses, allowing them to perhaps survive on surfaces for some time. It might be because the viruses use different transmission pathways compared to other viruses, meaning some interventions may work better than others.”

After a sharp decline, cases of RSV have gone up in recent months, leading the AAP to update its guidance to support the use of treatment in what would generally be the offseason for the respiratory disease. After a historically mild influenza season, experts have wondered what this season might look like.

“The striking interruption of respiratory virus transmission that we saw last year was unprecedented and we don’t have a good sense of what the long-term effects of this may be,” Midgley said.

References:

Common cold virus continued to circulate in the midst of the SARS-CoV-2 pandemic. https://www.idsociety.org/news--publications-new/articles/2021/common-cold-virus-continued-to-circulate-in-the-midst-of-the-sars-cov-2-pandemic/. Published Sept. 30, 2021. Accessed Sept. 30, 2021.

Rankin, DA, et al. Abstract 154. Presented at: IDWeek; Sept. 29-Oct. 3, 2021 (virtual meeting).