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Review 1: "Validation of the Panbio COVID-19 Antigen Rapid Test (Abbott) to screen for SARS-CoV-2 infection in Sint Maarten: a diagnostic accuracy study"

Published onMar 25, 2022
Review 1: "Validation of the Panbio COVID-19 Antigen Rapid Test (Abbott) to screen for SARS-CoV-2 infection in Sint Maarten: a diagnostic accuracy study"
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key-enterThis Pub is a Review of
Validation of the Panbio™ COVID-19 Antigen Rapid Test (Abbott) to screen for SARS-CoV-2 infection in Sint Maarten: a diagnostic accuracy study

AbstractObjectivesControl of the pandemic has required countries to look for other forms of tests besides the gold standard real-time polymerase chain reaction (RT-PCR). Rapid antigen tests (RAT), though less sensitive than RT-PCR, offer the possibility of rapid, inexpensive and early detection of the most infectious COVID-19 cases. Only very few studies have assessed the performance of the Abbott Panbio COVID-19 RAT among asymptomatic people or in Latin America. This study set out to validate this test among people attending the public test street in Sint Maarten, Dutch Caribbean.MethodsPeople of all ages were recruited from the public COVID-19 test street regardless of COVID-19 symptoms. They received a nasopharyngeal swab for the Abbott Panbio COVID-19 RAT and the RT-PCR Qtower. Diagnostic accuracy of the RAT was compared to the RT-PCR among the overall study population and for subgroups with/without symptoms, with/without close contact and different Ct values.ResultsUsing a RT-PCR Ct cut-off value of <33, 119 out of 1,411 people (8.4%) tested positive for SARS-CoV-2. Most were asymptomatic (59%). The overall sensitivity and specificity of the RAT was 84% (95% CI 76.2-90.1) and 99.9% (95% CI 99.6-100) respectively. The sensitivity reduced to 67.6% (95% CI: 49.5%, 82.6%) among people without symptoms, regardless of whether they were in close contact with a known COVID-19 case. Sensitivity reduced considerably with a Ct cut-off value of <35.ConclusionsThe Abbott Panbio RAT is a valid and cheaper alternative to RT-PCR when used on symptomatic individuals among the general population. However, among asymptomatic people it should not be used as a stand-alone test and negative results should be confirmed with RT-PCR.

RR:C19 Evidence Scale rating by reviewer:

  • Reliable. The main study claims are generally justified by its methods and data. The results and conclusions are likely to be similar to the hypothetical ideal study. There are some minor caveats or limitations, but they would/do not change the major claims of the study. The study provides sufficient strength of evidence on its own that its main claims should be considered actionable, with some room for future revision.



The authors evaluated the performance of the Panbio Abbott COVID-19 Rapid Antigen Test (RAT) to detect COVID-19 cases. COVID-19 cases were defined by RT-PCR.

The study was well-planned. It showed that the sensitivity of RAT to detect COVID-19 cases was higher in symptomatic individuals than asymptomatic individuals. However, the manuscript can be improved further.

This review was divided into two parts. The first part was the review of the manuscript, the second part was the recommendations of the manuscript.

1.        Review of the manuscript

1.1 Aims of the study

Existing method: RT-PCR was used to detect SARS-CoV-2 among symptomatic individuals. Asymptomatic individuals were also tested for contact cases and cases through contact tracing.

Suggested method: To assess if RAT can reduce the workloads on laboratories in Sint Maarten.

1.2 Methods

A statistics test was used to assess the minimum sample size needed. All ages of individuals irrespective of symptoms were recruited. The study period was from 11 Jan 2021 to 26 Feb 2021. One nasopharyngeal (NP) swab was for RAT while another NP swab was for RT-PCR. Three groups of data were collected and analyzed: (1) demographics, (2) clinical information, (3) test results. 

1.3 Results 

Among the 1411 individuals tested having Ct values, the prevalence of COVID-19 cases were 8.4% and 9.6% when Ct values cut-off were <33 and <35 respectively. Variables of having COVID-19 were assessed thoroughly to see if they were statistically significant.

Regarding RAT performance, when Ct values cut-off was <33, the sensitivity of RAT were 84.0%, 90.5%, 67.7% for overall, symptomatic and asymptomatic individuals respectively. The specificity was high, ≥99.9 among the three groups of individuals. 

1.4 Discussion

The diagnostic accuracy of the RAT found in the study was compared and discussed with other studies using the same RAT kit.

Limitations of the study were recognized.

The proposed usage of RAT based on the findings of the study was recommended.

2.        Recommendations of the manuscript 

2.1 Aims of the study

The aims of the study were clearly defined.

2.2 Methods

The sample size calculation of this study was based on the 5% of prevalence of COVID-19. The authors are recommended to justify this estimation.

The following technical operations of this study should be elaborated:

  • The place where respiratory specimens collected

  • If RAT was performed on-site

  • Was NP swab kept in viral transport medium tube for RT-PCR?

  • The conditions of temporary storage of NP swabs

  • Was there same-day transportation of NP swabs to St Maarten Laboratory for RT-PCR

  • Were RT-PCRs performed daily without freeze and thaw

  • The exact amplification cycles (e.g. 40 or 45) of the SARS-CoV-2 RT-PCR assay

  • COVID-19 positive cases should be defined using the same criteria as the routine practice, Ct<35

2.3 Results

COVID-19 positive cases in Tables 1-3 were based on different Ct cut-off values. Table 1 was defined as Ct<35 while Tables 2-3 were defined as Ct<33. COVID-19 positive cases should be presented and reported using the same criteria. 

The authors were right to present the performance of RAT on different viral load samples (Table 4).

An additional table can be prepared to present the distributions of different viral load samples (i.e. Ct<35, <30, <25) for symptomatic individuals and asymptomatic individuals.

2.4 Discussion

It is not necessary to adjust the Ct values to fit the guidelines or share concordant results with other studies. On the contrary, it is better to discuss the underlining reasons for finding discordant results.

The authors can also discuss the performance of RAT will be different when the prevalence of COVID-19 is changed. When prevalence increases, the sensitivity of RAT increases since the probability of having a positive case is increased. Conversely, when prevalence decreases, the specificity of RAT decreases since the probability of having a positive case is reduced [1]. This issue of discussion should be concordant with the findings based on the new table recommended in section 2.3.

3.        Conflicts of interest


4.        References

1. WHO. SARS-CoV-2 antigen-detecting rapid diagnostic tests: An implementation guide, 21 December 2020. Available at: (Accessed: 11 October 2021).


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