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In medicine, the window period for a test designed to detect a specific disease (particularly infectious disease) is the time between first infection and when the test can reliably detect that infection. In antibody-based testing, the window period is dependent on the time taken for seroconversion.

The window period is important to epidemiology and safe sex strategies, and in blood and organ donation, because during this time, an infected person or animal cannot be detected as infected but may still be able to infect others. For this reason, the most effective disease-prevention strategies combine testing with a waiting period longer than the test's window period.

Examples

HIV

The window period for HIV may be up to three months, depending on the test method and other factors. RNA based HIV tests has the lowest window period. Modern and accurate testing abilities can cut this period to 25 days, 16 days, or even as low as 12 days, again, depending on the type of test and the quality of its administration and interpretation.^[1]^[2]

Hepatitis B

Two periods may be referred to as window period in hepatitis B infection: ^{[citation needed]}

(1) the period that elapses during HBsAg to HBsAb seroconversion, i.e. between the disappearance of surface antigen (HBsAg) from serum and the appearance of HBsAb (anti-HBs), and

(2) the period between infection and appearance of HBsAg.

During the window of HBsAg to HBsAb seroconversion, IgM anti-core (HBc-IgM) is the only detectable antibody. HBV DNA may be positive as well. This window period does not occur in persons who develop chronic hepatitis B, i.e. who continue to have detectable HBV DNA for greater than 6 months (HbsAg remains positive), or in people who develop isolated HBcAb positivity, i.e. who lose HBsAg, but do not develop HBsAb (HBV DNA may or may not remain positive).^[3]

References

^ "HIV/AIDS Facts". Centers for Disease Control and Prevention. Retrieved 15 June 2014.
^ "HIV Test Window Periods". San Francisco AIDS Foundation. Retrieved 15 June 2014.
^ Lok, AS (2007). "Chronic Hepatitis B" (PDF). Hepatology. 45 (2): 507–39. doi:10.1002/hep.21513. hdl:2027.42/55941. PMID 17256718. S2CID 8713169.

[1] "HIV/AIDS Facts". Centers for Disease Control and Prevention. Retrieved 15 June 2014.

[2] "HIV Test Window Periods". San Francisco AIDS Foundation. Retrieved 15 June 2014.

[3] Lok, AS (2007). "Chronic Hepatitis B" (PDF). Hepatology. 45 (2): 507–39. doi:10.1002/hep.21513. hdl:2027.42/55941. PMID 17256718. S2CID 8713169.

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+{{short description|Period when an infection is not yet detectable for a given test}}
 In medicine, the '''window period''' for a test designed to detect a specific [[disease]] (particularly infectious disease) is the time between first [[infection]] and when the test can reliably detect that infection. In [[antibody]]-based testing, the window period is dependent on the time taken for [[seroconversion]].
@@ Line 4: / Line 5: @@
 == Examples ==
+===HIV===
-* '''HIV [[AIDS]]''': [http://aids.gov/hiv-aids-basics/prevention/your-hiv-status/testing-window-period/ U.S. Government site www.AIDS.gov] informs: "The timeframe between when you are exposed to HIV to the time you test positive for HIV antibodies can be up to 3-6 months. This period of time is called a “window period” for HIV testing. On average, you may need to wait 2 to 8 weeks from the time of possible exposure to get an accurate test result, because it takes at least that long for the immune system to develop enough HIV antibodies to be detectable."<ref>http://aids.gov/hiv-aids-basics/prevention/your-hiv-status/testing-window-period/ Government site www.AIDS.gov, "Testing Window Period"</ref>
+[[HIV test#Window period|The window period for HIV]] may be up to three months, depending on the test method and other factors. [[RNA]] based [[HIV]] tests has the lowest window period. Modern and accurate testing abilities can cut this period to 25 days, 16 days, or even as low as 12 days, again, depending on the type of test and the quality of its administration and interpretation.<ref>{{cite web|url=http://hivtest.cdc.gov/stronger/hiv/index.html|title=HIV/AIDS Facts|work=[[Centers for Disease Control and Prevention]]|access-date=15 June 2014}}</ref><ref>{{cite web|url=http://www.sfaf.org/hiv-info/testing/hiv-test-window-periods.html|title=HIV Test Window Periods|publisher=[[San Francisco AIDS Foundation]]|access-date=15 June 2014}}</ref>
+===Hepatitis B===
-[[HIV test#Window period|Related Wikipedia article]] informs:
+Two periods may be referred to as window period in [[hepatitis B]] infection: {{cn|date=January 2021}}
-"Antibody tests may give false negative (no antibodies were detected despite HIV being present) results during the window period, an interval of three weeks to six months between the time of HIV infection and the production of measurable antibodies to HIV seroconversion. Most people develop detectable antibodies approximately 30 days after infection, although some seroconvert later. The vast majority of people (97%) have detectable antibodies by three months after HIV infection; a six-month window is extremely rare with modern antibody testing. During the window period, an infected person can transmit HIV to others although their HIV infection may not be detectable with an antibody test. Antiretroviral therapy during the window period can delay the formation of antibodies and extend the window period beyond 12 months. This was not the case with patients that underwent treatment with post exposure prophylaxis (PEP). Those patients must take ELISA tests at various intervals after the usual 28 day course of treatment, sometimes extending outside of the conservative window period of 6 months. Antibody tests may also yield false negative results in patients with X-linked agammaglobulinemia; other diagnostic tests should be used in such patients."
+:(1) the period that elapses during HBsAg to HBsAb seroconversion, i.e. between the disappearance of surface antigen (HBsAg) from serum and the appearance of HBsAb (anti-HBs), and
+:(2) the period between infection and appearance of HBsAg.
-* '''Hepatitis B''': During the window period (or equivalence zone) of [[Hepatitis B]], both serological markers HBsAg (Hepatitis B surface antigen) and Anti-HBs ([[antibody]] against HBsAg) are negative (which is due to the fact that, although there are Anti-HBs antibodies present, they are actively bound to the HBsAg).  Other serological markers, IgM (antibody) against HBc can be positive at this point.<ref>p. 168, "Hepatitis serologic markers", {{cite book |author=Le, Tao, Bhushan, Vikas, Rao Deepak |title=First Aid for the USMLE STEP 1|publisher=McGraw Hill Medical |location=New York |year= 2008|pages= |isbn=978-0-07-149868-5 |oclc= |doi=}}, p.1943 "Harrison's Principles of Internal Medicine ed.17th"</ref>
+During the window of HBsAg to HBsAb seroconversion, IgM anti-core (HBc-IgM) is the only detectable antibody. HBV DNA may be positive as well. This window period does not occur in persons who develop chronic hepatitis B, i.e. who continue to have detectable HBV DNA for greater than 6 months (HbsAg remains positive), or in people who develop isolated [[HBcAb]] positivity, i.e. who lose HBsAg, but do not develop HBsAb (HBV DNA may or may not remain positive).<ref>{{Cite journal|last=Lok|first=AS|date=2007|title=Chronic Hepatitis B|journal=Hepatology|volume=45|issue=2|pages=507–39|pmid=17256718|doi=10.1002/hep.21513|hdl=2027.42/55941|s2cid=8713169|url=https://deepblue.lib.umich.edu/bitstream/2027.42/55941/1/21513_ftp.pdf|hdl-access=free}}</ref>
 ==See also==
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 {{DEFAULTSORT:Window Period}}
+{{Concepts in infectious disease}}
 [[Category:HIV/AIDS]]
 [[Category:Serology]]