Social Distancing Impacts Other Infectious Diseases

Christine Kilgore

September 14, 2020

Diagnoses of 12 common pediatric infectious diseases in a large pediatric primary care network declined significantly in the weeks after COVID-19 social distancing (SD) was enacted in Massachusetts, compared with the same time period in 2019, an analysis of EHR data has shown.

While declines in infectious disease transmission with SD are not surprising, "these data demonstrate the extent to which transmission of common pediatric infections can be altered when close contact with other children is eliminated," Jonathan Hatoun, MD, MPH of the Pediatric Physicians' Organization at Children's in Brookline, Mass., and coauthors wrote in Pediatrics. "Notably, three of the studied diseases, namely, influenza, croup, and bronchiolitis, essentially disappeared with [social distancing]."

The researchers analyzed the weekly incidence of each diagnosis for similar calendar periods in 2019 and 2020. A pre-SD period was defined as week 1-9, starting on Jan. 1, and a post-SD period was defined as week 13-18. (The several-week gap represented an implementation period as social distancing was enacted in the state earlier in 2020, from a declared statewide state of emergency through school closures and stay-at-home advisories.)

To isolate the effect of widespread SD, they performed a "difference-in-differences regression analysis, with diagnosis count as a function of calendar year, time period (pre-SD versus post-SD) and the interaction between the two." The Massachusetts pediatric network provides care for approximately 375,000 children in 100 locations around the state.

In their research brief, Dr. Hatoun and coauthors presented weekly rates expressed as diagnoses per 100,000 patients per day. The rate of bronchiolitis, for instance, was 18 and 8 in the pre- and post-SD–equivalent weeks of 2019, respectively, and 20 and 0.6 in the pre- and post-SD weeks of 2020. Their analysis showed the rate in the 2020 post-SD period to be 10 diagnoses per 100,000 patients per day lower than they would have expected based on the 2019 trend.

Rates of pneumonia, acute otitis media, and streptococcal pharyngitis were similarly 14, 85, and 31 diagnoses per 100,000 patients per day lower, respectively. The prevalence of each of the other conditions analyzed — the common cold, croup, gastroenteritis, nonstreptococcal pharyngitis, sinusitis, skin and soft tissue infections, and urinary tract infection (UTI) — also was significantly lower in the 2020 post-SD period than would be expected based on 2019 data (P < .001 for all diagnoses).

Putting Things in Perspective

"This study puts numbers to the sense that we have all had in pediatrics – that social distancing appears to have had a dramatic impact on the transmission of common childhood infectious diseases, especially other respiratory viral pathogens," Audrey R. John, MD, PhD, chief of the division of pediatric infectious disease at Children's Hospital of Philadelphia, said in an interview.

The authors acknowledged the possible role of families not seeking care, but said that a smaller decrease in diagnoses of UTI — generally not a contagious disease — "suggests that changes in care-seeking behavior had a relatively modest effect on the other observed declines." (The rate of UTI for the pre- and post-SD periods was 3.3 and 3.7 per 100,000 patients per day in 2019, and 3.4 and 2.4 in 2020, for a difference in differences of –1.5).

In an accompanying editorial, David W. Kimberlin, MD and Erica C. Bjornstad, MD, PhD, MPH, of the University of Alabama at Birmingham, called the report "provocative" and wrote that similar observations of infections dropping during periods of isolation – namely, dramatic declines in influenza and other respiratory viruses in Seattle after a record snowstorm in 2019 – combined with findings from other modeling studies "suggest that the decline [reported in Boston] is indeed real" (Pediatrics 2020. doi: 10.1542/peds.2020-019232).

However, "we also now know that immunization rates for American children have plummeted since the onset of the SARS-CoV-2 pandemic [because of a] ... dramatic decrease in the use of health care during the first months of the pandemic," they wrote. "Viewed through this lens," the declines reported in Boston may reflect inflections going "undiagnosed and untreated."

Ultimately, Dr. Kimberlin and Dr. Bjornstad said, "the verdict remains out."

Dr. John said that she and others are "concerned about children not seeking care in a timely manner, and [concerned] that reductions in reported infections might be due to a lack of recognition rather than a lack of transmission."

In Philadelphia, however, declines in admissions for asthma exacerbations, "which are often caused by respiratory viral infections, suggests that this may not be the case," said Dr. John, who was asked to comment on the study.

In addition, she said, the Massachusetts data showing that UTI diagnoses "are nearly as common this year as in 2019" are "reassuring."

Are There Lessons for the Future?

Coauthor Louis Vernacchio, MD, MSc, chief medical officer of the Pediatric Physicians' Organization at Children's network, said in an interview that beyond the pandemic, it's likely that "more careful attention to proven infection control practices in daycares and schools could reduce the burden of common infectious diseases in children."

Dr. John similarly sees a long-term value of quantifying the impact of social distancing. "We've always known [for instance] that bronchiolitis is the result of viral infection." Findings like the Massachusetts data "will help us advise families who might be trying to protect their premature infants (at risk for severe bronchiolitis) through social distancing."

The analysis covered both in-person and telemedicine encounters occurring on weekdays.

The authors of the research brief indicated they have no relevant financial disclosures and there was no external funding. The authors of the commentary also reported they have no relevant financial disclosures, and Dr. John said she had no relevant financial disclosures.

SOURCE: Hatoun J et al. Pediatrics. 2020. doi: 10.1542/peds.2020-006460.

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