What lab work is indicated for a patient experiencing recurrent Upper Respiratory Infections (URIs) followed by sinusitis after a severe Coronavirus Disease 2019 (COVID-19) infection?

From the Guidelines

For someone experiencing recurrent upper respiratory infections (URIs) and sinus infections following severe COVID-19, I strongly recommend comprehensive lab work including a complete blood count with differential, comprehensive metabolic panel, inflammatory markers (ESR, CRP), immunoglobulin levels (IgA, IgG, IgM, IgE), and specific antibody response testing, as suggested by recent guidelines 1. This approach is crucial because post-COVID syndrome can involve immune dysregulation that predisposes to recurrent infections. COVID-19 may damage respiratory epithelium and impair mucociliary clearance, creating vulnerability to secondary infections. Some patients develop post-viral immune deficiencies or reactivation of latent infections. Key tests to consider include:

• Complete blood count with differential to assess for any signs of infection or inflammation
• Comprehensive metabolic panel to evaluate overall health and detect any metabolic abnormalities
• Inflammatory markers (ESR, CRP) to gauge the level of inflammation in the body
• Immunoglobulin levels (IgA, IgG, IgM, IgE) to assess immune function and potential deficiencies
• Specific antibody response testing to determine the body's response to COVID-19 and other pathogens Additionally, requesting vitamin D levels, zinc, and other micronutrient testing is important, as deficiencies can impact immune function 1. Consideration of allergy testing (both blood IgE and skin testing) can help identify potential triggers for the recurrent infections. A sinus CT scan would be valuable to assess for structural abnormalities or chronic sinusitis, which could be contributing to the recurrent infections. The comprehensive lab work will help identify specific immune deficiencies, inflammatory patterns, or nutritional deficiencies that could be addressed with targeted treatments, potentially breaking the cycle of recurrent infections and improving quality of life. It's also important to note that the use of antimicrobial drugs should be restricted in mild-to-moderately ill patients with COVID-19 infection, especially in those with low, initial PCT levels (<0.25 ng/mL), as suggested by recent guidelines 1. Early de-escalation or discontinuation of antibiotics in COVID-19 patients with low PCT levels (<0.25 ng/mL) is also recommended 1. Serial PCT measurement in all patients during hospitalization, especially in critically ill or ICU patients under mechanical ventilation, can help guide antibiotic therapy 1.

From the Research

Lab Work for Post-COVID-19 Infections

Lab work for someone who has been constantly getting sick with URIs followed by sinus infections after a severe COVID-19 infection may involve several tests to determine the underlying cause of their symptoms.

• The patient's immune response to SARS-CoV-2 infection can be evaluated through various tests, including IgA, IgM, and IgG antibody tests 2.
• A study published in Nature Communications found that SARS-CoV-2-specific IgM, IgG, and IgA antibodies can be detected in respiratory tract and blood samples, and that receptor-binding domain (RBD)-specific IgM and IgG seroconversion is enhanced in respiratory specimens 3.
• Another study published in the International Journal of Environmental Research and Public Health found that primary SARS-CoV-2 infection provides some protection against reinfection and reduces the risk of symptomatic infection and severe illness 4.
• The patient's cytokine and chemokine levels can also be evaluated to assess their immune response and inflammation levels 3.
• A prospective multimodal evaluation of patients with long-term symptoms attributed to SARS-CoV-2 infection found that half of the patients lacked SARS-CoV-2 immunity, and that the presence or absence of immunity had no consequence on the clinical or biologic characteristics of post-acute COVID-19 syndrome patients 5.
• The Journal of Intensive Care Medicine published a study that discussed the evidence-based management of critically ill adults with SARS-CoV-2 infection, which may be relevant to patients who have experienced severe COVID-19 infection 6.

Possible Tests

Possible tests that may be ordered for this patient include:

• Complete Blood Count (CBC) to evaluate their white blood cell count and differential
• Erythrocyte Sedimentation Rate (ESR) or C-Reactive Protein (CRP) to assess their inflammation levels
• IgA, IgM, and IgG antibody tests to evaluate their immune response to SARS-CoV-2 infection
• Cytokine and chemokine panels to assess their immune response and inflammation levels
• SARS-CoV-2 serology tests to determine if they have developed immunity to the virus
• Imaging studies such as chest X-rays or CT scans to evaluate their lung function and rule out any underlying conditions that may be contributing to their symptoms.