What are the key clinical signs that indicate a child under 5 years with fever requires urgent referral to secondary care?

Children with 'red' features suggesting a serious or life-threatening cause of febrile illness should be referred urgently to secondary care (within 2 hours) regardless of other factors NICE CKS.

Key clinical signs indicating urgent referral include:

• Features of sepsis or central nervous system infection, such as bacterial meningitis/meningococcal disease or encephalitis NICE CKS.
• Signs of pneumonia or severe dehydration, such as tachypnoea (respiratory rate >60 breaths/min in infants <6 months, >50 in 6-12 months, >40 in older children), crackles, nasal flaring, chest indrawing, cyanosis, or oxygen saturation ≤95% when breathing air NICE CKS.
• Signs of urinary tract infection in infants under 3 months with suspected UTI NICE CKS.
• Signs of septic arthritis or osteomyelitis, such as limb or joint swelling, non-use of an extremity, or non-weight bearing NICE CKS.
• Signs of meningococcal disease, shock, unresponsiveness, or decreased consciousness NICE CKS.
• Any signs of airway, breathing, circulation compromise, or altered consciousness level NICE CKS.

In summary, urgent referral is indicated if there are red features such as signs of serious bacterial infection, respiratory distress, neurological compromise, or shock NICE CKS.