A Guide to Diagnostic, Surveillance & At-Home COVID-19 Testing

Test­ing for COVID-19 has been a crit­i­cal way to con­trol the spread of the virus through­out 2020. COVID-19 test­ing is evolv­ing, and new infor­ma­tion seems to be shared every day. It’s impor­tant to under­stand the dif­fer­ence between tests, in terms of their intend­ed use and per­for­mance, so you can best pro­tect your­self and your loved ones dur­ing this pandemic. 

What is the dif­fer­ence between Diag­nos­tic and Sur­veil­lance Testing? 

Diag­nos­tic test­ing is used to detect the pres­ence or absence of dis­ease in an indi­vid­ual. These tests are per­formed when there is rea­son to sus­pect that a per­son may be infect­ed with COVID-19, such as recent expo­sure and/​or the per­son is exhibit­ing symp­toms. Results from a diag­nos­tic test will pro­vide a pos­i­tive or neg­a­tive out­come, diag­nos­ing you with COVID-19 or rul­ing out an active infection. 

The major­i­ty of COVID-19 diag­nos­tic test­ing with­in the Unit­ed States has been con­duct­ed via Poly­merase Chain Reac­tion (PCR) tests. These tests look for genet­ic mate­r­i­al of the virus and are the most sen­si­tive tests for detect­ing an active infec­tion. For these tests, a health care provider will col­lect mucus from deep with­in your nose or throat using a spe­cial­ized swab. PCR tests require spe­cif­ic equip­ment and chem­i­cals typ­i­cal­ly locat­ed at off­site labs to read the results. There are both rapid and tra­di­tion­al (non-rapid) PCR tests avail­able, but the rapid PCR tests are not as sen­si­tive in detec­tion as tra­di­tion­al PCR tests. Diag­nos­tic PCR test­ing is the type of test­ing you will find at DuPage Med­ical Group COVID-19 Test­ing Sites as well as most local health depart­ment test­ing facilities.

Sur­veil­lance test­ing is used to mon­i­tor the COVID-19 risk at the com­mu­ni­ty or pop­u­la­tion lev­el. This type of test­ing is used to mon­i­tor things like whether the virus is affect­ing some groups of peo­ple more than oth­ers, or if its preva­lence is increas­ing or decreas­ing. Most sur­veil­lance test­ing does not use diag­nos­tic PCR test­ing and is not intend­ed for indi­vid­u­als who are exhibit­ing symp­toms of COVID-19. Instead sur­veil­lance test­ing uses anti­gen test­ing which is a rapid test that detects spe­cif­ic pro­teins on the sur­face of the virus. These tests have high­er false pos­i­tive and neg­a­tive results. There­fore, results from anti­gen sur­veil­lance test­ing only pro­vide an indi­ca­tion that there is a clin­i­cal­ly sig­nif­i­cant find­ing and usu­al­ly requires fur­ther diag­nos­tic PCR test­ing to con­firm an active COVID-19 infection.

Why are some school dis­tricts and busi­ness­es imple­ment­ing sur­veil­lance test­ing for a return to in-per­son class­es or work? 

Sur­veil­lance test­ing is being approved in some school dis­tricts and busi­ness­es due to the prox­im­i­ty of peo­ple in a con­fined loca­tion like a class­room or office space. This type of test­ing is admin­is­tered on a reg­u­lar ongo­ing basis to indi­vid­u­als who are not expe­ri­enc­ing symp­toms as an added safe­guard to min­i­mize the spread of COVID-19 with­in large groups. This test­ing will ensure that poli­cies put in place such as hand wash­ing, mask-wear­ing and social dis­tanc­ing are being fol­lowed and are effec­tive. These fre­quent screen­ings will allow schools and busi­ness­es to slow­ly increase in-per­son learn­ing and in-office work safely.

What are sali­va tests?

Sali­va tests are a new­er form of test­ing that is less inva­sive than the tra­di­tion­al PCR swab test. These do not require chem­i­cal reagents to be read mak­ing them more wide­ly avail­able. Ini­tial stud­ies are show­ing that sali­va tests are about as reli­able as the tra­di­tion­al PCR test that require the nasal swabs. Sali­va tests also elim­i­nate the need for health­care work­ers to encounter peo­ple who might be infect­ed since these tests don’t always need to be admin­is­tered by a health­care worker. 

What is anti­body testing?

An anti­body test looks for the pres­ence of anti­bod­ies in your blood. Anti­bod­ies are spe­cif­ic pro­teins that your body makes in response to an infec­tion. Pres­ence of COVID-19 anti­bod­ies in your body indi­cate you had the viral infec­tion and may show an immune response to it, even if you nev­er expe­ri­enced any symptoms.

It is impor­tant to note that while these tests can deter­mine who had the virus, we are not yet cer­tain if anti­bod­ies cre­at­ed in response to the COVID-19 infec­tion will pro­vide immu­ni­ty and/​or how long any immu­ni­ty will last. The CDC con­tin­ues to con­duct stud­ies on COVID-19 immu­ni­ty to deter­mine the answers to these questions.

Anti­body test­ing is per­formed by a blood test, either through a blood draw or fin­ger prick. This dif­fers from the swab test per­formed to deter­mine active COVID-19 infec­tion cas­es. DuPage Med­ical Group uses the Roche COVID-19 anti­body test and is the first out­patient med­ical group to obtain this test nation­al­ly. The Roche test is the most accu­rate anti­body test avail­able, with a high sen­si­tiv­i­ty that approach­es 100% that pro­vides us with the best results pos­si­ble. Learn more about anti­body test­ing here. 

What are the at-home test options and how can they be used? 

Over the past few months, the only at-home tests that were avail­able were home col­lec­tion kits. These kits cost on aver­age $100-$150 and are avail­able now at major retail­ers and test­ing com­pa­nies. To use the col­lec­tion kits, indi­vid­u­als swab their nos­trils or spit sali­va into a vial and send the sam­ple for pro­cess­ing at a lab which takes 24 – 48 hours to get results. 

In the past few weeks, the Food and Drug Admin­is­tra­tion (FDA) has autho­rized three dif­fer­ent rapid at-home tests with over 90% accu­ra­cy[1]. Indi­vid­u­als will be able to swab their nos­trils, run the test at home and can get results in about 15 – 30 min­utes. Luci­ra was the first at home test approved by the FDA and is for indi­vid­u­als ages 14 years or old­er, Ellume is the sec­ond test that was approved for indi­vid­u­als ages 2 years or old­er and Abbott’s BinaxNOW was the third at home test to receive approval for indi­vid­u­als ages 15 years or old­er. These three tests will be avail­able to the gen­er­al pub­lic over the next few months. 

To learn more about how to sched­ule your COVID-19 test with DuPage Med­ical Group, please vis­it our COVID-19 Test­ing Page. If you have addi­tion­al ques­tions about diag­nos­tic, anti­body, sur­veil­lance and at home test­ing, you can reach out to your DuPage Med­ical Group provider for more information.


[1] https://​www​.wash​ing​ton​post​.com/​h​e​a​l​t​h​/​2​0​2​0​/​1​2​/​1​6​/​c​o​r​o​n​a​v​i​r​u​s​-​h​o​m​e​-​t​e​s​t​-​r​apid/