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Low detection rate of RT-PCR-confirmed COVID-19 using IgM/IgG rapid antibody tests in a large community sample in
Stephanie Law1,2, Marco A Tovar3,4, Molly F Franke1
1Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, USA.
Insights
Rapid antibody tests for COVID-19 showed low overall sensitivity, performing poorly compared to RT-PCR tests. Their utility is limited, especially in early symptom stages, necessitating better diagnostic access during pandemics.
Area of Science:
- Infectious Diseases
- Diagnostic Accuracy
- Public Health
Background:
- Rapid IgM/IgG antibody tests were widely used for COVID-19 detection in Lima, Peru.
- Their diagnostic utility was assessed against RT-PCR (reverse transcription-polymerase chain reaction) testing.
Purpose of the Study:
- To evaluate the sensitivity of rapid IgM/IgG antibody tests for COVID-19.
- To explore the relationship between symptom onset timing and antibody test sensitivity.
Main Methods:
- A community sample of 492 individuals underwent concurrent RT-PCR and rapid antibody testing.
- Sensitivity was estimated using segmented regression analysis based on weeks since symptom onset.
Main Results:
- Overall sensitivity of the rapid antibody test was 46.7%.
- For symptomatic individuals, sensitivity increased from 30.4% in week 1 to 83.3% in week 4 post-symptom onset.
- Sensitivity peaked around weeks 2-3 and then declined.
Conclusions:
- Rapid antibody tests are not a reliable substitute for RT-PCR testing.
- Equitable access to gold-standard diagnostics is crucial for future pandemic preparedness.
Background:
Rapid IgM/IgG antibody tests were largely used in lieu of RT-PCR tests as part of COVID-19 public health response activities in Lima, Peru. To assess their utility, we explored the relationship between the time since onset of several COVID-19-related symptoms and the sensitivity of a rapid combined IgM/IgG antibody test.
Methods:
We collected data from a community sample of individuals (n = 492) who received concurrent RT-PCR and rapid IgM/IgG antibody testing between May 2020 and March 2021. We estimated the sensitivity of the antibody test, against the RT-PCR test, by weeks since symptom onset via segmented regression analysis.
Results:
The overall sensitivity of the rapid IgM/IgG antibody test was 46.7% (95% CI, 42.4-51.2%). Among 372 (75.6%) participants who reported COVID-19-related symptoms, sensitivity increased from 30.4% (95% CI, 24.7-36.6%) in week 1 after symptom onset to 83.3% (95% CI, 41.6-98.4%) in week 4. The test sensitivity increased by 31.9% (95% CI, 24.8-39.0%) per week until week 2 to 3, then decreased by - 6.0% (95% CI, - 25.7-13.7%) per week thereafter.
Conclusion:
Rapid antibody tests are a poor substitute for RT-PCR testing, regardless of presenting symptoms. This highlights the need for future pandemic planning to include timely and equitable access to gold-standard diagnostics, treatment, and vaccination.
