Multisystem Inflammatory Syndrome (MIS-C) Clinical Pathway — Emergency, ICU and Inpatient

Talking Points for Serologic Testing for COVID-19 for Families Requesting Testing

Monitor Clinical Response

Explain what an antibody is to get the conversation started –
- Antibodies are specific proteins made in response to infections.
- Antibodies can be found in the blood, usually within 1-2 weeks after infection and show that people have had an immune response to the infection.
- Antibodies usually remain present for months or even years.
What do we know about antibodies that result from COVID-19 infection?
- We are still learning about this. Some labs and companies have developed tests that can show if you have had a recent infection, whether you had symptoms or not. The accuracy of these tests, however, can vary.
Will having antibodies to COVID-19 protect me from getting infected in the future?
- Unfortunately, we don’t know if the antibodies that result from COVID-19 infection will prevent a future infection or, if they do provide protection, how long it will last.
When will we know?
- The CDC and researchers around the world are working hard to study antibody responses to COVID-19 in children and adults who have been infected to better understand how many people have been infected, if antibodies will protect against future infections, and how antibody tests can be used for the general population. This might take several months.

Serologic Testing FAQs For Providers

Can antibody tests be used to diagnose a current COVID-19 infection?
- No. A positive antibody would suggest exposure to SARS-CoV-2, not necessarily active infection at the time of testing.
If an antibody test is positive, does it mean the patient has previously been infected with SARS-CoV-2?
- Not necessarily. The positive test may be a false positive, particularly if the local prevalence of SARS-CoV-2 is low and/or the patient is at low risk for having been exposed. SARS-CoV-2. SARS-CoV-2 antibody tests may also cross react with some other types of coronaviruses.
If an antibody test is positive, does it mean the patient is immune to SARS-CoV-2?
- No. Antibody titers are not measured in commercially available assays and the titer required for protective immunity is not yet known, nor is the duration of immunity. Relying on antibody tests in this way risks providing false reassurance to patients, providers, and family and is one key reason that testing for this reason is not indicated.
Should testing for IgG, IgM and IgA be obtained?
- Serum IgG or total antibody testing is recommended; if being used to detect prior infection, a test 3-4 weeks after symptom onset is recommended.
- Unlike many other viral infections, IgM to SARS-CoV-2 does not increase early on after infection and appears to remain relatively low, unlike IgG. IgM testing is therefore not sufficiently sensitive for diagnosis, such that routine use of this test is not recommended.
- IgA testing appears less specific than IgG testing and is therefore not routinely recommended.

When SHOULD Serologic Testing be Considered?

As part of a research study (vaccine development, public health surveillance study)
As part of a vaccine clinical trial
Hospitalized children presenting with clinical syndromes consistent with Multisystem Inflammatory Syndrome in Children (MIS-C), in consultation with Infectious Disease
To determine whether a patient >18 years old may be a candidate for convalescent plasma donation
Outside of these scenarios, sending serologic testing is generally not appropriate. In particular, serologic testing should not be used to screen for prior infection, to determine if a previous compatible illness was attributable to SARS-CoV-2, or for children with febrile illness not compatible with the criteria for MIS-C set forth in this guidance.
Inappropriate serologic testing may result in misinformation given the risk of false positive, especially in low likelihood/prevalence settings, and further, may be misinterpreted by patients/families as evidence of immunity.
For all of these reasons, approval from infectious diseases is needed when sending serologic testing.

References

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The clinical pathways are based upon publicly available medical evidence and/or a consensus of medical practitioners at The Children’s Hospital of Philadelphia (“CHOP”) and are current at the time of publication. These clinical pathways are intended to be a guide for practitioners and may need to be adapted for each specific patient based on the practitioner’s professional judgment, consideration of any unique circumstances, the needs of each patient and their family, and/or the availability of various resources at the health care institution where the patient is located.

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