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Table 2 Summary and synthesis of algorithms for balancing missed cases and NAAT volumea

From: Quantitative comparison of SARS-CoV-2 nucleic acid amplification test and antigen testing algorithms: a decision analysis simulation model

Algorithmsa to Consider

Prosb

Consb

Synthesis

Impact of Prevalence

(C) NAAT for Sx/Ag-neg & Asx/Ag-pos

1. Moderate missed cases

2. Low NAAT volume

3. Low false positives

1. Moderate unneeded quarantine while waiting for results

2. High Ag volume

NAATs have the greatest accuracy but also greatest requirements in cost, time, personnel, and infrastructure. Programs often need to balance accuracy (case detection) and cost (NAAT volume).

(D) results in no missed cases and saves between 4% NAAT test volume (at 5% prevalence) and 15% NAAT test volume (at 20% prevalence) relative to (A).

(C) results in more missed cases but greatly reduces NAAT test volume (by 66%) compared to (A). This will save between 93 (at 5% prevalence) and 93 (at 20% prevalence) NAATs for each additional case missed.

(E) eliminates NAAT entirely but substantially increases missed cases (23% compared to (A)). This will save between 87 (at 5% prevalence) and 22 (at 20% prevalence) NAATs for each additional case missed.

At low prevalence, cases are rare and many NAATs are needed for each case detected in (C), (D) and (E).

As prevalence increases, cases increase more than NAAT volume increases and fewer NAATs are needed for each case detected in (C), (D) and (E). Absolute numbers of missed cases increase more and (E) than (C) (and remain 0 for (A) and (D)).

As prevalence increases, the efficiency of (C), (D), and (E) becomes more favorable, while the negative consequences of (C) and (E) become less favorable.

(D) NAAT for Ag-neg

1. No missed cases

1. High false-positives

2. High NAAT volume

3. High Ag volume

4. High unneeded quarantine while waiting for results

(E) Repeat Ag for Ag-neg

1. No NAAT infrastructure required

2. No unneeded quarantine while waiting for results

1. High missed cases

2. Highest false-positives

3. Highest Ag volume

(A) NAAT Only

1. No missed cases

2. No false positives

3. No need for Ag testing infrastructure

1. Highest NAAT volume

2. Highest unneeded quarantine while waiting for results

  1. a See Supplementary Table S3 for summary and synthesis of algorithms for other programmatic priorities
  2. bSee Methods and Fig. 1 for full descriptions of each algorithm evaluated. Algorithms are listed in order of favorability for balancing missed cases and NAAT volume. Algorithm (B), which does not implement NAATs, is excluded
  3. § Except where stated otherwise, numerical results are simplified by rank order for summary as follows: Highest refers to the algorithm for which the outcome is the highest number (compared to all other algorithms, across prevalence levels); High refers to algorithms which result in the second- or third-highest level outcome of algorithms evaluated; Moderate refers to the middle level of outcome (when outcomes from multiple algorithms are equal); Low refers to algorithms with result in the second- or third-lowest level of outcome; Lowest refers to the algorithm for which the outcome is lowest (when this lowest level is zero, this is stated as, e.g., “No missed cases”). See Results and Fig. 2 for exact numerical results
  4. Abbreviations: NAAT – nucleic acid amplification tests (such as RT-PCR); Ag – antigen; Ag-pos - positive antigen result; Ag-neg - negative antigen result
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BMC Public Health

ISSN: 1471-2458

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