Query Helps Identify ED Visits After Vaccination


  • The development of multiple COVID-19 vaccines in 2020 highlighted the importance of safety monitoring systems to ensure benefits outweigh the risks.
  • State and local partners of the National Syndromic Surveillance Program (NSSP) expressed interest in using emergency department (ED) data to monitor safety.
  • NSSP developed and shared a query to identify mentions of adverse events after recent vaccination (VAE) during ED visits or in ambulatory health care settings.
Senior woman getting vaccinated

Full story

On Dec. 11, 2020, the Advisory Committee on Immunization Practices (ACIP) recommended the Pfizer-BioNTech COVID-19 vaccine for people 16 years of age and older in the United States. On Dec. 19, 2020, the ACIP recommended the Moderna COVID-19 vaccine for people 18 years of age and older.

To make sure the benefits outweigh the risks for people who get vaccinated, several vaccine safety monitoring systems are in place to watch for adverse events (possible side effects). To further support these systems, state and local partners of NSSP have expressed interest in exploring the use of ED data to monitor safety.

In response, CDC NSSP developed and shared the first version of this query: CDC Vaccine-Associated Adverse Events v1. This query (shown below) is designed to identify mentions of adverse events after recent vaccination (VAE) during ED visits or in ambulatory health care settings. The query (syndrome definition) can be found in the ESSENCE chief complaint and discharge diagnosis (CCDD) category field.

The query includes a broad combination of diagnosis codes (ICD-10, ICD-9, and SNOMED) and chief complaint terms to detect visits potentially related to an adverse reaction after recent vaccination (e.g., poisoning, anaphylactic reaction, infection, post-vaccination fever, meningoencephalitis). This query does not attempt to identify specific clinical outcomes.

Given that discharge diagnosis can lag after chief complaint and is occasionally less complete, the NSSP team included chief complaint terms to improve timeliness and provide detailed reason-for-visit information. The chief complaint terms are designed to be more sensitive than specific and could identify ED visits unrelated to a recent vaccination or associated adverse event.

Public health professionals can help work on queries‎

To join the group working on queries or to ask questions about applying these searches to ED data in your public health jurisdiction, e-mail nssp@cdc.gov.

CDC Vaccine-Associated Adverse Events v1 definition

Search CC field and also apply to DD field: (,(,^vaccin^,or,^immuniz^,or,(,^shot^,and,(,^ flu^,or,flu^,or,^influenza^,or,^shingles^,or,^pne^,or,^pna^,or,^tetn^,or,^tetanu^,or,^tdap^,or,^booster^,or,^td^,or,^hpv^,or,^mmr^,or,^covid^,or,^corona^,),),),and,(,^reaction^,or,^allerg^,or,^adverse^,or,^side effect^,or,^had^,or,^received^,or,^got^,or,^was given^,or,^after^,or,^post^,or,^last time^,or,^recent^,or,^since getting^,or,^since receiving^,or,^since yesterday^,),or,^shot^,AND,(,^Reaction^,or,^Allergic^,or,^Adverse^,),),andnot,(,^no vaccine^,or,^no immuniz^,or,^immunization not carried^,or,^[;/ ]Z28.21^,or,^[;/ ]Z2821^,or,^[;/ ]P55.1^,or,^[;/ ]P551^,or,^dog^,or,^cat^,or,^wound^,or,^up to date^,or,^ABO isoimmunization of newborn^,or,^well child^,or,^well visit^,or,^encounter for immunization^,or,^loss of consciousness^,or,^aftercare^,or,^UTD^,or,^up to date^,or,^bite^,or,^air vac^,or,^denies any previous adverse reaction^,or,^did not receive^,or,^poison ivy^,or,^allergic rhinitis^,or,^voiced no complaints^,),or,^[;/ ]T50[ABZ]^,or,^[;/ ]T50.[ABZ]^,or,^[;/ ]T80.52^,or,^[;/ ]T8052^,or,^[;/ ]T80.62^,or,^[;/ ]T8062^,or,^[;/ ]T88.[01]^,or,^[;/ ]T88[01]^,or,^[;/ ]R50.83^,or,^[;/ ]R5083^,or,^[;/ ]G04.32^,or,^[;/ ]G0432^,or,^[;/ ]G04.02^,or,^[;/ ]G0402^,or,^[;/ ]123471000119103[;/ ]^,or,^[;/ ]15920121000119100[;/ ]^,or,^[;/ ]219075006[;/ ]^,or,^[;/ ]219084006[;/ ]^,or,^[;/ ]293104008[;/ ]^,or,^[;/ ]293109003[;/ ]^,or,^[;/ ]293116002[;/ ]^,or,^[;/ ]293118001[;/ ]^,or,^[;/ ]293120003[;/ ]^,or,^[;/ ]293125008[;/ ]^,or,^[;/ ]31935007[;/ ]^,or,^[;/ ]408672009[;/ ]^,or,^[;/ ]47988006[;/ ]^,or,^[;/ ]219088009[;/ ]^,or,^[;/ ]293117006[;/ ]^,or,^[;/ ]420113004[;/ ]^,or,^[;/]97[89][;/ ]^,or,^[;/ ]97[89].[0-9][;/ ]^,or,^[;/ ]97[89][0-9][;/ ]^,or,^[;/ ]964.6[;/ ]^,or,^[;/ ]9646[;/ ]^,or,^[;/ ]999.0[;/ ]^,or,^[;/ ]9990[;/ ]^,or,^[;/ ]999.39[;/ ]^,or,^[;/ ]99939[;/ ]^,or,^[;/ ]999.[45]2[;/ ]^,or,^[;/ ]999[45]2[;/ ]^,or,^[;/ ]780.63[;/ ]^,or,^[;/ ]78063[;/ ]^,or,^[;/ ]323.5[;/ ]^,or,^[;/ ]323.5[12][;/ ]^,or,^[;/ ]3235[;/ ]^,or,^[;/ ]3235[12][;/ ]^

Date Created: 2020-12-10