COVID Resource Center

Learn More About Testing and Vaccine

How is COVID-19 diagnosed?

In the United States, diagnostic testing for COVID-19 involves testing for the presence of the virus in specimens obtained from patients. Almost all diagnostic testing for COVID-19 is done using PCR-based methods, which look for the genetic material of the SARS-CoV-2 virus, which causes COVID-19. These methods can only diagnose someone with COVID-19 if they are actively infected. Currently, most diagnostic tests for COVID-19 test nasopharyngeal or oropharyngeal specimens (nose or throat swabs). Recently, the FDA granted Emergency Use Authorization to a laboratory to test patients’ saliva.

What are limitations to COVID-19 diagnostic tests?

With any diagnostic test, there is the potential for false negatives or false positives. For existing COVID-19 tests in the U.S., there have been reports of false negative tests in some patients. False negative tests can occur if a specimen was not properly obtained or if a patient was tested too early or too late in their infection. Laboratory error is also a possible cause of false negative test results. Conversely, false positive reports are less common.

Who should be tested for COVID-19?

Individuals who have symptoms of COVID-19 should be tested for the SARS-CoV-2 virus so that they will know to isolate themselves from others so as not to spread the disease. In certain cases, such as outbreak investigation, testing of people without symptoms is also indicated. However, current limitations in testing capacity have restricted who may be tested for COVID-19.

Recommendations regarding who should and can be tested differ by state. Some states that have experienced large numbers of COVID-19 cases have requested that individuals who are experiencing symptoms of COVID-19 assume that they are positive and avoid health facilities unless they experience severe symptoms.

What are the difference test types for Covid 19?

There are two main types of diagnostic tests: Molecular tests are the most accurate but usually must be analyzed by lab technicians. Antigen tests are fast and inexpensive but less accurate.

What they have in common:

  • Both are collected by throat and nasal swabs
  • Both issue a positive or negative result
  • While these tests can measure viral load, they can’t tell you how “serious” a course of illness you might have
  • Both have rapid point-of-care options—which don’t require specialized lab work

Molecular tests look for the virus’s genetic material and are the current standard for diagnosing COVID-19.

Method: Nasal or throat swab, and for some tests, saliva

Turnaround: Varies by type of test

  • Most testing sites use polymerase chain reaction (PCR) tests, which are very accurate but are usually performed in large certified labs and require skilled lab workers. Results can take several days to come back. These tests are required by some larger industries and some airlines.
  • Rapid point-of-care molecular tests, such as Abbott’s ID NOW, can provide results within 13 minutes.
  • Both the PCR test and Rapid Covid Test are available at OneSource in our Drive Thru testing area. Appointments are required. Learn More.

How long does it take to get test results?

Timely test results are important to inform clinical care and to support public health measures to control COVID-19. The sooner patients receive test results, the sooner infected individuals can be isolated, before they transmit their infection to others. And, the contacts of infected individuals can be traced and monitored so that they, too, can take preventive measures to avoid spreading the disease.

Currently, the time it takes to get testing results in the U.S. can vary based on several factors. Different testing technologies produce results in different time frames. For example, some testing machines promise results in <30 minutes, whereas some laboratory methods can take hours. At OneSource Healthcare, we offer the Rapid COVID test and the results are available within 30 minutes. The PCR test can take several days for results.

Do patients have to pay to get tested?

In March 2020, the U.S. Congress passed and the President signed into law the Families First Coronavirus Response Act, which requires governmental and private insurance plans to cover the cost of COVID-19 testing. The law does not protect against out-of-network charges or charges for visits for possible coronavirus infection that do not result in testing. While Congress set aside funds to test the uninsured, it is possible that some people without insurance will nonetheless be billed. The law does not cover the cost of COVID-19 treatment.

Most frequently asked questions on COVID-19 vaccines


How do vaccines work?

Vaccines stimulate the human body’s own protective immune responses so that, if a person is infected with a pathogen, the immune system can quickly prevent the infection from spreading within the body and causing disease. In this way, vaccines mimic natural infection but without actually causing the person to become sick.

For SARS-CoV-2, antibodies that bind to and block the spike protein on the virus’s surface are thought to be most important for protection from disease because the spike protein is what attaches to human cells, allowing the virus to enter our cells. Blocking this entrance prevents infection.

Not all people who are infected with SARS-CoV-2 develop disease (Covid-19 is the disease caused by the virus SARS-CoV-2). These people have asymptomatic infection but can still transmit the virus to others. Most vaccines do not completely prevent infection but do prevent the infection from spreading within the body and from causing disease. Many vaccines can also prevent transmission, potentially leading to herd protection whereby unvaccinated people are protected from infection by the vaccinated people around them because they have less chance of exposure to the virus.

How will we know if a vaccine is safe and effective?

The safety and efficacy of a vaccine is determined through clinical trials. Clinical trials are studies that are typically conducted in three phases to assess the safety and efficacy of vaccines in increasingly larger numbers of volunteers.

Phase 1 clinical trials assess the safety and dosage of a vaccine in a small number of people, typically a dozen to several dozen healthy volunteers. Whether a vaccine stimulates immune responses is often assessed in a phase 1 study but this is better assessed in phase 2 studies, which typically involve hundreds of people including some special groups such as children, people with pre-existing conditions such as heart disease, and older adults. Vaccine safety is also assessed in phase 2 studies, in which adverse events not detected in phase 1 trials may be identified because a larger and more diverse group of people receive the vaccine. However, only in much larger phase 3 clinical trials can it be demonstrated whether a vaccine is actually protective against disease and safety is more fully assessed.

Phase 3 clinical trials often include thousands of volunteers, and for Covid-19 vaccines will involve tens of thousands (30,000 to 45,000 people in some of the ongoing phase 3 trials). In phase 3 trials, participants are randomized to receive either the viral vaccine or a placebo vaccine (sometimes a vaccine against another disease or a harmless substance like saline). Randomization is a process to determine who receives the vaccine and who receives the placebo without any bias, like flipping a coin. To further prevent any bias in interpreting the study data, participants and most of the investigators will not know if an individual received the vaccine or placebo. The participants are then followed to see how many in each group get the disease. If the vaccine is efficacious, many fewer people who received the viral vaccine will get the disease compared to those who received the placebo vaccine. It takes time for cases of disease to accumulate so that we can be confident there is a true difference between the two groups, and this is why these phase 3 trials often take a long time. Assessing safety is also a major goal of phase 3 trials, both short-term safety (e.g. fever, tenderness, muscle aches) and long-term safety (e.g. autoimmune conditions or enhanced disease following infection).

After a vaccine is approved and in more widespread use, it is critically important to continue to monitor for both safety and effectiveness. Some very rare side effects may only be detectable when large numbers of people have been vaccinated. Safety concerns that are discovered at this late stage could lead a licensed vaccine to be withdrawn from use, although this is very rare.

Should I get the vaccine for influenza (flu shot)?

Yes, it is very important to get the influenza vaccine, particularly this season when both influenza viruses and SARS-CoV-2 will infect people. We still do not know how these two viruses will interact but people can get infected with both viruses and this will likely cause more severe disease and possibly death. Reducing the number of people who get severe influenza and require hospitalization will also help ensure that the health care system, hospitals and intensive care units will not be overwhelmed should there be an increase in Covid-19 cases this fall and winter. Flu shots are free with most insurance.

Attribution: Johns Hopkins University of Medicine/Coronavirus Resource Center/2020