Differential Diagnosis for a 10-year-old Boy with Cough, Congestion, and Vomiting after COVID-19 Recovery

Single Most Likely Diagnosis

• Viral upper respiratory infection (post-COVID-19 secondary infection): This is likely due to the recent COVID-19 infection, which can predispose individuals to secondary infections, especially viral upper respiratory infections. The symptoms of cough, congestion, and vomiting are consistent with this diagnosis, and the normal lab results with no significant increase in white blood cell count support a viral etiology.

Other Likely Diagnoses

• Asthma exacerbation: Given the cough and congestion, if the boy has a history of asthma, an exacerbation could be a likely diagnosis, especially if triggered by the recent viral infection.
• Allergic rhinitis: Seasonal allergies could cause similar symptoms, and the recent COVID-19 infection might not be directly related but could exacerbate underlying allergies.
• Gastroenteritis: Although the primary symptoms are respiratory, the vomiting could indicate a gastrointestinal involvement, possibly due to a viral gastroenteritis, which is common in children.

Do Not Miss Diagnoses

• Bacterial pneumonia: Although less likely given the normal lab results, bacterial pneumonia is a serious condition that requires prompt antibiotic treatment. The recent COVID-19 infection could increase susceptibility to bacterial superinfections.
• Influenza or other viral pneumonias: Co-infection or superinfection with influenza or other respiratory viruses could present similarly and has significant implications for treatment and prognosis.
• Mycoplasma pneumonia: This atypical pneumonia can present with mild symptoms and normal initial lab results but requires specific antibiotic treatment.

Rare Diagnoses

• COVID-19 relapse or prolonged infection: Although rare, some individuals can experience a relapse of COVID-19 symptoms or have a prolonged course of the illness.
• Immunological complications post-COVID-19: Rare immunological reactions or complications following COVID-19 infection, such as multisystem inflammatory syndrome in children (MIS-C), although the timing and symptoms might not perfectly align, it's crucial to consider given the recent COVID-19 infection.
• Other rare infections: Such as pertussis (whooping cough) or less common viral infections that could present with similar symptoms.