Southern California's Orange County Health Department this month declared a local health emergency over concerns around the rising number of pediatric cases of Respiratory Syncytial Virus (RSV).

County officials also declared a Proclamation of Local Emergency, allowing them to access state and federal resources in response to the spread of RSV.

The news came amid media warnings of a looming "tripledemic" of RSV, influenza and COVID-19 and news that Pfizer and GlaxoSmithKline (GSK) are close to securing regulatory approval for their RSV vaccine candidates — including Pfizer's RSV vaccine for pregnant women.

RSV was first identified in 1956, and frequently affects children, with a majority of childhood cases occurring before age 2. For most children, symptoms are similar to those of the common cold, according to the Centers for Disease Control and Prevention (CDC).

It can, however, cause serious symptoms in the very young and the elderly, although childhood deaths are infrequent, according to CDC data.