COVID-19 Tests: What’s the Difference?

Helping you Make an Informed Decision About Your Coronavirus Testing Strategy

| By E&I Cooperative Services

Strategically testing for COVID-19 is crucial in the fight against this pandemic. Even with increasing vaccine availability on the horizon, this is especially true for educational institutions as they continue to focus on safeguarding the health and safety of students in the coming months.

A recent NPR analysis of data collected on 1,400 institutions by the College Crisis Initiative at Davidson College revealed that more than two-thirds have no clear testing plan, or are only testing at-risk individuals when they feel sick or have confirmed contact with someone who has tested positive.

According to the analysis, “Of colleges with in-person classes and more than 5,000 undergraduates, only 25% are conducting mass screening or random ‘surveillance’ testing of students. Only 6% are routinely testing all of their students. Most, instead, are relying on only diagnostic testing of symptomatic students, which many experts say comes too late to control outbreaks and understates the true number of cases.”

With experts insisting that widespread testing for COVID-19 is a necessity, it’s imperative for decision-makers at educational institutions to understand the types of tests available to make an informed decision about their institution’s testing strategy.

The three main methods of testing for the coronavirus are molecular, antigen, and antibody tests. Medline has recently released an infographic detailing how each test is administered, how they work, and the advantages and limitations of each. The summary of this infographic is outlined below.

Three Main Methods of COVID Testing

Molecular Test

  • What is it?
    Molecular testing detects the presence of the SARS-CoV-2 virus RNA. A positive test result can be an indicator that the patient has an active COVID infection.
  • How are samples collected?
    A deep nasal swab collects virus particles.
  • If infected, how does the testing work?
    If a patient is infected, when tested using this method, the RNA derived from the sample is transcribed into DNA and amplified. This results in a positive test result.
  • What are the advantages?
    Molecular testing indicates if the patient is currently infected. It can also detect early infections and provides highly sensitive and specific results.
  • What are the limitations?
    Molecular testing is unable to detect those who’ve been infected and later recovered. This results in the possibility of a false negative if a patient has been recently infected.

Antigen Test

  • What is it?
    Antigen testing detects the presence of the SARS-CoV-2 virus particles. A positive test result can be an indicator that the patient has an active COVID infection.
  • How are samples collected?
    A deep nasal swab collects virus particles.
  • If infected, how does the testing work?
    As the infection progresses, viral particles can be measured using immunoassay techniques.
  • What are the advantages?
    Antigen testing indicates if the patient is currently infected. It can also detect early infections, and its simple designs lead to rapid results. Antigen tests are more suited to test large numbers of people.
  • What are the limitations?
    Antigen testing is unable to detect those who’ve been infected and later recovered. This results in the possibility of a false negative if a patient has been recently infected.

Antibody Test

  • What is it?
    Antibody/Serology testing detects antibodies to the SARS-CoV-2 virus. A positive test result can be an indicator that the patient has mounted an immune response to the virus.
  • How are samples collected?
    A blood draw collects antibodies produced by immune cells.
  • If infected, how does the testing work?
    After two days, IgM antibodies are produced to attack the virus. After 9-11 days, tailored antibodies called IgG are produced. These antibodies are then measured using immunoassay techniques to determine if a patient had been infected.
  • What are the advantages?
    Antibody tests reliably detect an immune response to the virus. Their simple design leads to rapid results and is more suited to test large numbers of people.
  • What are the limitations?
    Antibody tests cannot distinguish if a patient is contagious or if an infection is still present. There is also the possibility of false negatives if a patient has been recently infected or has a delayed immune response. It is unknown if the presence of antibodies confers immunity.

Selecting a Test to Fit Your Needs

When determining which testing method applies for your institution, there are several considerations that come into play, such as your geographic location (which affects levels of community transmission), student and staff population, funding, campus housing, and commuting.

The Centers for Disease Control and Prevention recommends institutions work collaboratively with health department officials to determine the nature and implementation of any screening or testing strategy. This strategy also needs to be done as part of your larger COVID-19 plan, which should consider the implementation of testing strategies and what actions are to be taken based on test results.


About Medline

Medline is is the largest privately-held manufacturer and distributor of medical and surgical supplies in the U.S. The ability to deal directly with a manufacturer and distributor of top brands provides members with access to an extensive product offering, as well as the added value of expedited support and controlled costs.

Find out more about E&I’s competitively solicited Medline contract.


< Previous: Why Your School Should Recycle Your Old Batteries & Light Bulbs
> Next: Supplier Spotlight: VWR, part of Avantor

Share this:
0 comments

Leave a Reply