Monthly increases in sudden infant death syndrome (SIDS) in 2021 coincided with seasonal outbreaks of respiratory viruses, particularly respiratory syncytial virus (RSV), suggesting that changes in SIDS rates may be related to changes in infectious disease transmission, reports Penn State Health News.

The researchers published their findings in the journal JAMA Network Open.

In 2022, approximately 3,700 infants died unexpectedly in the United States, according to the Centers for Disease Control and Prevention (CDC). SUID is an umbrella term for unexpected death of an infant under the age of one year from known and unknown causes.

The research team examined the rate of both SUID and SIDS during the COVID-19 pandemic and compared it to the immediate period prior to the pandemic. Between March 1, 2018, and December 31, 2021, there were 14,308 cases of SUID, based on national data on mortality provided by the CDC.

The research team found that the risk of SUID and SIDS increased during the pandemic when they compared monthly cases to the pre-pandemic period. The greatest increase was observed in 2021 when rates for SUID and SIDS increased 9% and 10%, respectively, compared to the pre-pandemic period.

There was a notable shift in SUID rates from June to December 2021, when the monthly rate of SUID increased between 10% and 14% compared to pre-pandemic levels.