COVID-19 Is Less Frequent and Severe in Infants Than Other Respiratory Viruses, Study Finds

A study found infants under 2 months of age were less likely to experience SARS-CoV-2 infection and less severe illness compared with other respiratory viruses.

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Many studies have focused on the symptoms and effects of COVID-19, but few have compared SARS-CoV-2 data with other respiratory viruses. A new study challenges the idea that COVID-19 is a frequent and severe illness in very young children.

A recent retrospective single-center study in France published Oct. 5 in Pediatric Pulmonology found infants under 2 months of age were less likely to experience SARS-CoV-2 infection and less likely to experience severe illness compared with other viral respiratory infections.  Additionally, researchers found young children with COVID-19 required less respiratory support, enteral nutrition, or intensive care admission—and had shorter hospital stays—than children with other respiratory viruses.

Researchers tested 727 children under age 2 for SARS-CoV-2 from March 2021 through February 2022 in emergency room and hospital settings. This one-year period covered Alpha, Delta, and Omicron SARS-CoV-2 variants.

Of the 727 children tested, 62 tested positive for SARS-CoV-2. Of the 565 children who received a multiplex RT-PCR (reverse transcription polymerase chain reaction) test for other viruses, 325 tested positive (58 percent). The most frequently detected respiratory viruses during the one-year pandemic period were enterovirus/rhinovirus (28 percent) and respiratory syncytial virus (RSV) (27 percent). Only 0.5 percent of cases involved influenza viruses.

During the study, children were slightly less likely to test positive for other respiratory viruses during the Omicron period and more likely to test positive during periods where SARS-CoV-2 positivity rates were low.

The paper’s authors said this could be due to the initially circulating COVID-19 variant’s affinity for the respiratory tract and low immune system stimulation in babies and children, or it could be a result of social distancing requirements and initial lockdowns. However, the frequency of infection with respiratory viruses other than SARS-CoV-2, such as RSV, enteroviruses, and rhinoviruses, was high despite pandemic measures.

Even though SARS-CoV-2 infections were more prevalent during the Omicron period, the admission rate in intensive care units remained low, according to the study.

Researchers found that young children with COVID-19 were less likely to be admitted from the emergency department to the hospital, had shorter hospital stays, experienced less severe symptoms, and were less likely to require oxygen therapy and other medical interventions. For children who did need oxygen therapy, the duration of treatment was shorter for SARS-CoV-2 positive children than children with other respiratory viruses.

When compared to children with a positive RSV test, children with a positive SARS-CoV-2 test were significantly more likely to have fever and diarrhea but considerably less likely to have bronchiolitis—a viral infection that targets the airways in a child’s lungs, making it difficult for them to breathe. Those with positive RSV tests experienced more severe symptoms and a greater need for medical intervention.

Compared to children with viral respiratory infections other than RSV, children with positive SARS-CoV-2 tests were more likely to experience fever but less likely to experience bronchiolitis. Children with positive COVID-19 tests were older, had fewer comorbidities, were more likely to have a fever, and had significantly shorter hospital stays than those who tested negative for COVID-19 but positive for other respiratory illnesses.

The results of the study are consistent with recent data published by the Centers for Disease Control and Prevention (CDC), showing very few hospitalizations among infants under 6 months of age, with the greatest number of hospitalizations occurring when the Omicron variant was the dominant SARS-CoV-2 strain. In its numbers, the CDC included any child who tested positive for SARS-CoV-2 within 14 days before or during hospitalization—meaning a child could be included in COVID-19 hospitalization data even if they were asymptomatic or hospitalized for a reason unrelated to COVID-19.

The CDC uses this data to justify maternal vaccination policies even though original and current formulations were not assessed for safety or efficacy in pregnant women during clinical trials.