Children are commonly hospitalized because of community-acquired pneumonia. Despite the fact that many of these children have viral disease, a majority is treated with antibiotics. These antibiotics will not accelerate recovery in those with viral pneumonia and can cause harm. We are interested in exploring whether the MeMed BV - a composite biomarker assay - could be used to improve antibiotic prescribing in these children by identifying those who likely have viral disease. This proposal describes a feasibility randomized trial of this diagnostic intervention.

Inclusion Criteria:

• children with a history of fever who are hospitalized with CAP (ie. 'severe CAP') as per the clinical team and who have abnormal chest imaging (eg. radiograph, ultrasound) will be eligible. They must also have at least one of the following:

  1. documented tachypnoea (>60 bpm for age <1 y, >50 bpm for 1-2 y, >40 bpm for 2-4 y, and >30 bpm for >4 y);
  2. cough on exam or by history;
  3. increased work of breathing on exam; or
  4. auscultatory findings (eg. focal crackles, bronchial breathing) consistent with CAP.

Exclusion Criteria:

• Children will be excluded from if they have received >48h of intravenous antibiotics (eg. if transferred from another healthcare facility) or if they have a lobar consolidation that occupies the majority of a lobe on imaging, a pleural effusion that occupies more than ¼ of a lung field, or a positive blood culture for a bacterial pathogen (not a contaminant). Examples of CAP pathogens include S. pneumoniae, S. pyogenes (group A streptococcus), S. aureus, S. anginosus. Examples of contaminants that would be ignored include the coagulase-negative staphylococci and Bacillus spp. Children will also be excluded if they have any of the following: chronic lung disease, congenital heart disease (requiring treatment or with exercise restrictions), malignancy, immunodeficiency (primary, acquired, or iatrogenic), a separate episode of pneumonia previously diagnosed within the past 2 weeks, or lung abscess diagnosed within the past six months. Children will not be eligible to participate more than once.