12-phase flow (12)

1. 1FRAME
   Pediatric influenza spectrum: uncomplicated febrile ILI / influenza pneumonia (primary viral) / bacterial superinfection (S. aureus including MRSA + S. pneumoniae + S. pyogenes — biphasic illness pattern) / influenza-associated neurologic disease (IAND) / acute necrotizing encephalopathy (ANE) / myocarditis / MIS-C-like post-viral hyperinflammatory / otitis media overlay; age stratification (neonate / infant / toddler / preschool / school-age / adolescent); strain (H1N1 / H3N2 / B-Victoria / A-unsubtyped); host risk (< 5 yr, asthma, immunocompromised, CHD, neuromuscular, sickle cell, chronic metabolic, on long-term aspirin — Reye); severity tier; distinguished from adult id.influenza.core.v1 by pediatric dosing + Reye contraindication + peds-specific complications (AAP Red Book 2025-26; IDSA 2018 PMID 30566567; CDC peds 2025-26)
   inputs: age, symptom_onset_time
   advance: Pediatric influenza phenotype framed (uncomplicated / pneumonia / bacterial superinfection / ANE-IAND / myocarditis / MIS-C-like / otitis overlay) and host-risk + age + severity stratified
2. 2ENTRY
   Trigger: pediatric ILI presentation during influenza season + community influenza activity; positive rapid molecular flu PCR or multiplex; household or school / daycare outbreak exposure; respiratory failure features (SpO2 drop, retractions, age-specific tachypnea); altered mental status / seizures (ANE / IAND flag); chest pain + arrhythmia (myocarditis flag); biphasic illness pattern (bacterial superinfection flag); 2-6 wk post-influenza multi-organ inflammation (MIS-C-like flag); close contact within 48 h of confirmed case + high-risk host or < 5 yr (PEP eligible); annual vaccination eligible ≥ 6 mo per ACIP 2025-26
   advance: Entry trigger captured
3. 3CONTEXT
   Age + weight (for dosing) + comorbidities (asthma — zanamivir contraindicated; immunocompromised — extend oseltamivir to 10 d; CHD; neuromuscular / developmental affecting respiratory drive; sickle cell; chronic metabolic; on long-term aspirin — assess for discontinuation per Reye risk); influenza vaccination status (does NOT exclude diagnosis but attenuates severity); household + school / daycare contacts + community influenza activity level (peds peak season Dec-Mar Northern Hemisphere; secondary attack rate ~ 15-30% in unvaccinated household contacts); pregnancy in adolescents (cross-reference adult id.influenza.core.v1 for pregnant adolescent dosing)
   inputs: weight, peds_high_risk_conditions, long_term_aspirin_use_for_reye_risk, asthma_or_chronic_lung_disease, immunocompromise_status, influenza_vaccination_status
   advance: Pediatric host + exposure + comorbidity + vaccination context captured
4. 4RED_FLAGS
   Pediatric danger signs requiring immediate hospitalization or ICU consideration: (1) respiratory failure — SpO2 < 92% RA, retractions, grunting, age-specific tachypnea (RR ≥ 60 < 5 yr / ≥ 40 5-12 yr / ≥ 30 ≥ 12 yr) → admit + HFNC / CPAP / BiPAP / mechanical ventilation per PEWS; (2) altered mental status / seizures / focal neurological deficits → ANE / IAND concern → ICU + neurology + EEG + MRI + empiric IV acyclovir pending HSV PCR + continue oseltamivir; (3) chest pain + new ECG changes + elevated troponin → myocarditis → echo + cardiology + telemetry + continue oseltamivir; (4) biphasic illness pattern + new focal consolidation + procalcitonin > 0.25 → bacterial superinfection (S. aureus including MRSA + S. pneumoniae + S. pyogenes) → add empiric amoxicillin/clavulanate outpatient overlap OR ceftriaxone ± vancomycin inpatient; cross-route to peds.cap.v1; (5) dehydration with inability to maintain PO → IV fluids + admit; (6) age < 6 mo with significant febrile illness → febrile-infant pathway; (7) immunocompromised with progressive symptoms → extend oseltamivir + ID consult; (8) on long-term aspirin (juvenile RA, Kawasaki disease) — discontinue if possible during acute influenza per Reye risk (AAP Red Book 2025-26; CDC peds 2025-26; IDSA 2018 PMID 30566567)
   inputs: oxygen_saturation, pediatric_respiratory_rate_age_specific, altered_mental_status_or_seizures
   actions: flag:admit_if_spo2_lt_92_with_retractions (AAP Red Book 2025-26), flag:picu_if_ane_iand_or_myocarditis_features (Mizuguchi Brain Dev 1997 PMID 11057302; Steininger Clin Infect Dis 2003), flag:empiric_oseltamivir_age_weight_banded_do_not_wait_for_test_result_in_high_risk (AAP Red Book 2025-26; IDSA 2018 PMID 30566567), flag:no_aspirin_reye_syndrome_use_acetaminophen_or_ibuprofen (AAP Red Book 2025-26), flag:bacterial_superinfection_empirics_if_biphasic_illness_focal_consolidation_procalcitonin_high (IDSA 2018 PMID 30566567; IDSA/ATS CAP 2019)
   advance: Pediatric red flags assessed; empiric antiviral initiated; aspirin discontinued if applicable; admission disposition determined
5. 5INITIAL_WORKUP
   Pediatric influenza diagnostic testing: rapid molecular flu PCR (Xpert Xpress Flu, ID NOW) preferred over RIDT per IDSA 2018; multiplex flu/COVID/RSV PCR appropriate during respiratory season; RT-PCR gold standard for hospitalized + immunocompromised; CBC with differential (leukopenia + lymphopenia + thrombocytopenia common in severe; leukocytosis with neutrophil predominance disproportionate to influenza lymphopenia → bacterial superinfection); BMP for hydration + renal function; blood + sputum cultures if bacterial superinfection suspected (AAP Red Book 2025-26; CDC peds 2025-26; IDSA 2018 PMID 30566567)
   inputs: rapid_molecular_flu_pcr, cbc_with_differential, bmp_for_renal_function
   actions: panel.cbc, panel.renal, test:rapid_molecular_flu_pcr_or_multiplex (IDSA 2018 PMID 30566567; CDC peds 2025-26), lab:rt_pcr_gold_standard_if_hospitalized_or_immunocompromised (IDSA 2018 PMID 30566567)
   advance: Pediatric influenza testing ordered; initial labs obtained; empiric oseltamivir initiated if indicated
6. 6BRANCHING_WORKUP
   Evaluate pediatric complications: (1) primary viral pneumonia (bilateral ground-glass opacities on CXR, low procalcitonin) vs bacterial superinfection (focal consolidation, elevated procalcitonin > 0.25, leukocytosis disproportionate, biphasic illness — S. aureus including MRSA + S. pneumoniae + S. pyogenes) — cross-route to peds.cap.v1; (2) ANE / IAND — MRI brain (symmetric thalamic / brainstem / cerebellar lesions per Mizuguchi pattern), EEG, LP + CSF (rule out HSV — empiric IV acyclovir pending PCR per Tunkel IDSA encephalitis 2008), neurology consult; (3) myocarditis — ECG + troponin + BNP + echo + cardiology consult + telemetry; consider cardiac MRI if available; (4) MIS-C-like post-influenza hyperinflammatory (2-6 wk post-illness — multi-organ + Kawasaki-disease-like + elevated CRP/ferritin/ESR/D-dimer) — cardiac echo + inflammatory panel + ID + cardiology + rheum consult; (5) otitis media overlay — amoxicillin per AAP otitis media 2013; (6) rhabdomyolysis — CK; (7) status epilepticus — neurology + AED management (AAP Red Book 2025-26; Mizuguchi Brain Dev 1997 PMID 11057302; Steininger Clin Infect Dis 2003; Sun MMWR 2021)
   inputs: chest_xray_if_respiratory, procalcitonin_for_bacterial_superinfection, chest_pain_or_arrhythmia_in_peds_flu
   actions: panel.inflammation, imaging:cxr_if_hypoxia_dyspnea_or_persistent_fever (AAP Red Book 2025-26), lab:procalcitonin_to_guide_antibiotics (IDSA 2018 PMID 30566567; IDSA/ATS CAP 2019), lab:blood_cultures_sputum_culture_if_suspected_superinfection (IDSA 2018 PMID 30566567), imaging:mri_brain_eeg_if_encephalopathy_or_seizures (Mizuguchi Brain Dev 1997 PMID 11057302), lab:troponin_ecg_echo_if_chest_pain_or_arrhythmia (Steininger Clin Infect Dis 2003)
   advance: Pediatric complications evaluated or excluded; sub-specialty consults engaged as indicated
7. 7DIFFERENTIAL
   Pediatric influenza vs RSV bronchiolitis (< 2 yr — wheeze + retractions + crackles + URI prodrome — cross-route to peds.bronchiolitis.v1 — multiplex PCR distinguishes; can co-exist) vs SARS-CoV-2 (co-test recommended; cross-route to id.covid19.core.v1) vs peds CAP (bacterial — focal consolidation + procalcitonin; cross-route to peds.cap.v1) vs adenovirus (conjunctivitis + pharyngitis + cervical lymphadenopathy) vs croup (barking cough + inspiratory stridor — laryngotracheobronchitis; usually parainfluenza) vs pertussis (paroxysmal cough + post-tussive emesis + apnea infants < 6 mo — cross-route to id.pertussis.v1) vs strep pharyngitis (rapid strep + exudate + cervical lymphadenopathy + absent cough — Centor criteria) vs other viral URI (rhino, hMPV, parainfluenza) vs early sepsis (toxic appearance + perfusion abnormalities — cross-route to id.sepsis.peds.v1); multiplex respiratory PCR (flu + COVID + RSV + adeno + parainfluenza + hMPV + rhino) discriminates among viral etiologies (AAP Red Book 2025-26; CDC peds 2025-26; IDSA 2018 PMID 30566567)
   advance: Pediatric influenza confirmed or alternative diagnosis pursued; co-infection evaluated
8. 8RISK_STRATIFICATION
   Stratify pediatric severity + setting: (1) outpatient mild — ≥ 5 yr healthy + SpO2 ≥ 94% + tolerating PO + no high-risk host + no complications → symptomatic care + acetaminophen/ibuprofen + hydration + return precautions + shared-decision antiviral if ≤ 48 h onset; (2) outpatient high-risk — high-risk host (< 2 yr, asthma, immunocompromised, CHD, neuromuscular, sickle cell, chronic metabolic, on long-term aspirin) → empiric oseltamivir age/weight-banded × 5 d regardless of symptom-onset window per AAP Red Book 2025-26 + IDSA 2018; (3) inpatient moderate — SpO2 < 94% / dehydration / progressive symptoms / age < 6 mo with significant illness / failed outpatient management → admit + empiric oseltamivir + supportive care + complication surveillance; (4) PICU severe — respiratory failure (SpO2 < 92% with retractions + age-specific tachypnea, failing HFNC / CPAP) / ANE-IAND (altered MS, seizures, symmetric thalamic / brainstem MRI lesions) / myocarditis with hemodynamic compromise / leukostasis (WBC > 100 000) with pulmonary HTN features / multi-organ dysfunction → PICU + extended oseltamivir + sub-specialty consults; PEWS score for risk escalation per institutional protocol (AAP Red Book 2025-26; IDSA 2018 PMID 30566567; CDC peds 2025-26)
   inputs: peds_high_risk_conditions, oxygen_saturation, pediatric_respiratory_rate_age_specific
   advance: Pediatric severity tier + setting + complication phenotype assigned
9. 9TREATMENT
   Pediatric antiviral therapy: (1) oseltamivir age + weight-banded — first-line all ages including infants < 1 mo; term neonate 0-1 mo 3 mg/kg/dose PO BID × 5 d; 1-12 mo 3 mg/kg/dose PO BID × 5 d; ≥ 1 yr weight-banded ≤ 15 kg 30 mg BID / > 15-23 kg 45 mg BID / > 23-40 kg 60 mg BID / > 40 kg 75 mg BID × 5 d; extend to 10 d if ICU or immunocompromised with persistent viral shedding; (2) baloxavir ≥ 5 yr healthy / ≥ 12 yr high-risk — single dose 40 mg (< 80 kg) or 80 mg (≥ 80 kg) per CDC peds 2025-26 (FDA peds expansion to ≥ 5 yr in 2022 healthy children); (3) peramivir ≥ 6 mo IV single dose if PO not feasible — 12 mg/kg IV (max 600 mg) for ≥ 6 mo to < 13 yr; 600 mg IV ≥ 13 yr; (4) zanamivir ≥ 7 yr inhaled BID × 5 d — AVOID in asthma + chronic lung disease per bronchospasm risk. Supportive care: acetaminophen 10-15 mg/kg/dose PO q4-6h PRN (max 75 mg/kg/d), ibuprofen 5-10 mg/kg/dose PO q6-8h PRN (avoid < 6 mo and in dehydration); **NO ASPIRIN per Reye syndrome per AAP Red Book 2025-26**; hydration IV NS if poor PO or dehydration; supplemental O2 to SpO2 ≥ 94%; HFNC 1-2 L/kg/min for moderate-severe respiratory distress; CPAP/BiPAP/intubation for failure; ARDSnet ventilation if PaO2/FiO2 ≤ 200. Secondary bacterial coverage if pneumonia overlay (focal consolidation + procalcitonin > 0.25 + biphasic illness): amoxicillin/clavulanate (outpatient overlap — 80-90 mg/kg/d amoxicillin component PO divided BID × 7-10 d) OR ceftriaxone IV (inpatient — 50-100 mg/kg/d) ± vancomycin (15 mg/kg q6 h if anti-MRSA needed); cross-route to peds.cap.v1 for definitive CAP management. Empiric IV acyclovir pending HSV PCR if encephalopathy / seizures per Tunkel IDSA encephalitis 2008. PEP for high-risk close contacts: oseltamivir age/weight-banded daily × 7 d per CDC peds 2025-26 (AAP Red Book 2025-26; IDSA 2018 PMID 30566567; CDC peds 2025-26)
   inputs: age, weight
   advance: Pediatric antiviral initiated (age/weight-banded); supportive care ordered (acetaminophen/ibuprofen + hydration + oxygen); aspirin discontinued if applicable; secondary bacterial coverage if pneumonia overlay; sub-specialty consults engaged
10. 10DISPOSITION
    Outpatient: uncomplicated peds influenza ≥ 5 yr healthy + SpO2 ≥ 94% + tolerating PO + reliable family + return precautions in place. Admit: high-risk host with progressive symptoms, SpO2 < 94%, retractions, age-specific tachypnea, dehydration, age < 6 mo with significant illness, pneumonia overlay, otitis with parental-concern features. PICU: respiratory failure, ANE / IAND, myocarditis with hemodynamic compromise, leukostasis with pulmonary HTN, multi-organ dysfunction, sepsis. Discharge afebrile ≥ 24 h without antipyretics + tolerating PO + sustained SpO2 ≥ 94% RA + reliable follow-up + return precautions documented in caregiver-readable format (AAP Red Book 2025-26; IDSA 2018 PMID 30566567)
    advance: Pediatric setting + duration of care assigned; family education + return precautions delivered
11. 11MONITORING
    Outpatient: symptom resolution 5-7 days expected; biphasic illness pattern → return for bacterial superinfection eval; persistent fever > 3 d → reassess; return precautions on respiratory deterioration, dehydration, altered MS, chest pain. Inpatient: daily PEWS reassessment, respiratory status, SpO2, complication surveillance (neuro exam, cardiac auscultation, abdominal exam for hepatic involvement); clinical improvement expected day 3-5 on oseltamivir; if no improvement reassess for resistance + alternative diagnosis. PICU: continuous cardiopulmonary monitoring, daily neurological exam, serial troponin if myocarditis, ventilator management per ARDSnet, daily viral shedding assessment in immunocompromised. Aspirin reconciliation post-illness — resume if held for Reye risk only after illness resolution + clinician oversight per pediatric rheumatology / cardiology (AAP Red Book 2025-26)
    advance: Pediatric monitoring parameters + return precautions established; clinical improvement confirmed or escalation triggered
12. 12FOLLOWUP
    Post-influenza pediatric follow-up: annual influenza vaccination if unvaccinated this season + next season per ACIP 2025-26 (LAIV ≥ 2 yr healthy non-pregnant non-immunocompromised non-asthma; IIV otherwise; all ≥ 6 mo); household + school contact PEP for high-risk contacts (oseltamivir age/weight-banded × 7 d for high-risk within 48 h of exposure); school return when afebrile ≥ 24 h without antipyretics per CDC public health guidance; cardiology follow-up if myocarditis (echo at 3 + 6 mo; activity restriction per ACC/AHA peds myocarditis statement); neurology + neuropsych follow-up if ANE / IAND (serial imaging + functional assessment; mortality 30-50% in severe ANE per Mizuguchi 1997 PMID 11057302; long-term sequelae common); ID follow-up if immunocompromised; rheum + cardiology if MIS-C-like; public health reporting if institutional outbreak; aspirin reconciliation if held for Reye risk (AAP Red Book 2025-26; CDC peds 2025-26; ACIP 2025-26)
    advance: Pediatric follow-up + vaccination + sub-specialty referrals + return precautions delivered