我听说过 2019 冠状病毒病（COVID-19）的抗体检测。什么是抗体检测？是否与诊断 2019 冠状病毒病（COVID-19）的检测相同？
回答 William F. Marshall, III M.D.
2019 冠状病毒病（COVID-19）检测引发了广泛的讨论，使得人们对各种检测及其之间的区别感到困惑。抗体检测可确定您过去是否患过 COVID-19，以及当前是否有 COVID-19 病毒的抗体。COVID-19 诊断检测可确定您目前是否携带 COVID-19 致病病毒。以下是您需要了解的检测事项。
何时进行抗体检测？该项检测为何如此重要？
抗体检测，也称为血清学检测，通常在 COVID-19 完全康复后进行。检测的资格可能会有所不同，具体取决于检测的供应量。专业医务人员会采集血液样本，通常是通过手指采血或从手臂上的静脉抽血。然后，会对样本进行检测，以确定您是否对 COVID-19 致病病毒产生了抗体。免疫系统会产生抗体，一种在对抗和清除病毒方面发挥重要作用的蛋白质。
如果检测结果显示您有抗体，则表明您可能在过去某个时间感染了 COVID-19 病毒，或您在接种疫苗后产生了抗体。这也可能意味着您有免疫力。但是，拥有抗体，不一定意味着您可避免再次感染 COVID-19。不过，抗体有助于预防重病。目前还不清楚免疫的效力和持续时间，相关研究仍在进行之中。
抗体检测的时机和类型会影响准确性。如果感染过程中过早检测，身体尚在建立免疫反应，抗体检测可能无法检测到抗体。因此，建议在开始出现症状后至少 2 至 3 周再进行抗体检测。美国食品药品管理局（FDA）已批准某些抗体检测，但市场上部分检测仍存在准确性问题。
准确抗体检测的另一益处是，从 COVID-19 中痊愈的人群可获得捐献血浆的资格。血浆是其血液的一部分。这种血浆可用于治疗其他重症患者，增强其对抗病毒的能力。医生称之为恢复期血浆。
诊断 2019 冠状病毒病（COVID-19）有哪些检测方法？
FDA 已批准将以下检测用于诊断 COVID-19：
RT-PCR 检测。该 COVID-19 检测也称为分子检测，使用反转录聚合酶链式反应这一实验室技术来检测病毒的遗传物质。可使用鼻拭子或咽拭子采集体液样本，也可通过将唾液吐入试管中以产生唾液样本。
如果进行现场分析，则可能需要几分钟时间就能拿到结果，如果对延迟的检测结果进行分析，则可能在几天内得到结果。如果发送到外部实验室，则需要更长的时间。如果由专业医务人员正确进行 RT-PCR 检测，则检测结果会非常准确，但快速检测可能漏掉病例。
抗原检测。该项 COVID-19 检测可检测病毒中的某些蛋白质。抗原检测是利用鼻拭子获取体液样本，可在数分钟内得出结果。其他可能被送往实验室进行分析。
只要仔细遵循说明书，阳性抗原检测结果非常准确。但出现假阴性的几率却很大，也即是说，患者有可能已感染病毒，但检测结果呈阴性。根据情况，医务人员可能会建议进行 RT-PCR 检测，以验证阴性的抗原检测结果。
FDA 批准部分家用 COVID-19 检测试剂盒可供紧急使用，其中包括一种可同时检测 COVID-19 和流感的试剂盒。您可在家中自行采集鼻液或唾液样本，然后送到实验室进行快速分析。其中一些检测需要医生开处方。
有些 COVID-19 检测无需将样本送往实验室，在家中即可快速得出结果。一些非处方抗原检测试剂盒无需处方即可购买。但普遍认为抗原检测的可靠性不及 PCR 检测。如果检测结果为阴性，请再做一次检测，以确保检测结果的准确性。
这些检测的准确度各异。阴性检测结果并不能完全排除没有 COVID-19 病毒。请只进行经 FDA 授权或经当地卫生部门批准的家用检测试剂盒。
如果我想进行 COVID-19 诊断检测或抗体检测，该怎么办？
您可以致电联系所在州或当地卫生部门，或者访问其网站了解相关检测信息。如果您出现 COVID-19 症状或接触过 COVID-19 患者，应接受检测。如果您出现 COVID-19 症状，请联系医务人员以评估症状，并在询问检测事宜后再前往，便于工作人员为您的就诊做好准备。
能否进行这两种检测，取决于您住在何处、检测试剂盒的供应量以及您是否符合资格。
诊断和抗体检测如何帮助减少 COVID-19 传播？
开展 COVID-19 诊断检测后，检测结果呈阳性且有症状的患者可更早得到治疗。可尽早开始自我隔离或检疫隔离，以帮助阻止 COVID-19 病毒的传播。
但是，没有任何一种 COVID-19 检测是 100% 准确。很有可能检测结果为阴性，但实际上却已被感染（假阴性结果），或者检测结果为阳性，但实际上并未被感染（假阳性结果）。因此，请务必继续采取 COVID-19 预防措施，例如定期洗手、远离拥挤人群和视情况佩戴口罩。如果感觉不舒服，请待在家里并避免接触他人。
抗体检测的结果可显示感染 COVID-19 并康复的患者人数，包括无症状感染者。另外，还有助于确定哪些人可能有免疫力，但目前尚不清楚免疫效力和免疫时间。
With
William F. Marshall, III M.D.
June 11, 2022
- AskMayoExpert. COVID-19: Testing. Mayo Clinic; 2022.
- Patel R, et al. Report from the American Society for Microbiology COVID-19 International Summit, 23 March 2020: Value of diagnostic testing for SARS-CoV-2/COVID-19. MBio. 2020; doi:10.1128/mBio.00722-20.
- Overview of testing for SARS-CoV-2, the virus that causes COVID-19. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/hcp/testing-overview.html. Accessed Jan. 25, 2022.
- EUA authorized serology test performance. U.S. Food and Drug Administration. https:// www.fda.gov/medical-devices/coronavirus-disease-2019-covid-19-emergency-use-authorizations-medical-devices/eua-authorized-serology-test-performance. Accessed Jan. 25, 2022.
- Beware of fraudulent coronavirus tests, vaccines and treatments. U.S. Food & Drug Administration. https://www.fda.gov/consumers/consumer-updates/beware-fraudulent-coronavirus-tests-vaccines-and-treatments. Accessed Oct. 29, 2020.
- West CP, et al. COVID-19 testing: The threat of false-negative results. Mayo Clinic Proceedings. 2020; doi:10.1016/j.mayocp.2020.04.004.
- Coronavirus (COVID-19) update: Serological tests. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-serological-tests. Accessed April 16, 2020.
- Coronavirus (COVID-19) update: FDA authorizes additional OTC home test to increase access to rapid testing for consumers. U.S. Food and Drug Administration. https:// www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-additional-otc-home-test-increase-access-rapid-testing. Accessed Jan. 25, 2022.
- Abbasi J. The promise and peril of antibody testing for COVID-19. JAMA. 2020; doi:10.1001/jama.2020.6170.
- Coronavirus (COVID-19) update: Serological test validation and education efforts. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-serological-test-validation-and-education-efforts. Accessed April 28, 2020.
- COVID-19 natural immunity. World Health Organization. https://www.who.int/publications/i/item/WHO-2019-nCoV-Sci_Brief-Natural_immunity-2021.1. Accessed Jan. 25, 2022.
- IDSA COVID-19 antibody testing primer. Infectious Diseases Society of America. https://www.idsociety.org/globalassets/idsa/public-health/covid-19/idsa-covid-19-antibody-testing-primer.pdf. Accessed Oct. 30, 2020.
- Coronavirus (COVID-19) update: FDA authorizes first test for patient at-home sample collection. U.S. Food and Drug Administration. https:// www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-first-diagnostic-test-using-home-collection-saliva. Accessed April 29, 2020.
- Coronavirus testing basics. U.S. Food and Drug Administration. https:// www.fda.gov/consumers/consumer-updates/coronavirus-disease-2019-testing-basics. Accessed Jan. 25, 2022.
- COVID-19 testing: What you need to know. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/testing.html. Accessed Jan. 25, 2022.
- Coronavirus (COVID-19) update: FDA authorizes first diagnostic test using at-home collection of saliva specimens. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-first-diagnostic-test-using-home-collection-saliva. Accessed May 12, 2020.
- Coronavirus (COVID-19) update: FAQs on Testing for SARS-CoV-2. What is the difference between the types of tests available for SARS-CoV-2? U.S. Food and Drug Administration. https://www.fda.gov/medical-devices/emergency-situations-medical-devices/faqs-testing-sars-cov-2#5eb3418a8c19f. Accessed Oct. 27, 2020.
- Coronavirus (COVID-19) update: FDA authorizes first antigen test to help in the rapid detection of the virus that causes COVID-19 in patients. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-first-antigen-test-help-rapid-detection-virus-causes. Accessed May 14, 2020.
- Marshall, WF III (expert opinion). Mayo Clinic. Aug. 15, 2020.
- Coronavirus (COVID-19) update: FDA posts new template for at-home and over-the-counter diagnostic tests for use in non-lab settings, such as homes, offices or schools. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-posts-new-template-home-and-over-counter-diagnostic-tests-use-non. Accessed Aug. 11, 2020.
- Potential for false positive results with antigen tests for rapid detection of SARS-CoV-2 — Letter to clinical laboratory staff and health care providers. U.S. Food and Drug Administration. https://www.fda.gov/medical-devices/letters-health-care-providers/potential-false-positive-results-antigen-tests-rapid-detection-sars-cov-2-letter-clinical-laboratory. Accessed Nov. 4, 2020.
- Using antibody tests for COVID-19. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antibody-tests.html. Accessed Jan. 25, 2022.
- AskMayoExpert. COVID-19: Testing — Serologic antibody testing. Mayo Clinic; 2021.
- COVID-19 nasal swab type now determined at time of collection and may limit test "add-on" options: IP nurses will still complete the NP swab. Physical Medicine and Rehabilitation Newsletter — RST. Mayo Clinic. Nov. 18, 2020.
- Coronavirus (COVID-19) update: FDA authorizes first COVID-19 test for self-testing at home. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/coronavirus-covid-19-update-fda-authorizes-first-covid-19-test-self-testing-home. Accessed Nov. 19, 2020.
- Interim guidance for antigen testing for SARS-CoV-2. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antigen-tests-guidelines.html. Accessed Jan. 25, 2022.