This standard EN14675 tests virucidal activity efficacy outlines the evaluation of product that are used in the veterinary area.
THE PROFICIENCY TESTING PROCEDURE IN THE VIRUCIDAL ACTIVITY
- The first step is to read deeply the protocol to test virucidal activity of the product sent together with the sample where we including the test conditions (contact time, concentrations testing (if applicable), interfering substance, target virus, etc.)
- Second step involves preparing a suspension of the target virus (Bovine enterovirus 1 type (ECBO) ATCC VR-248. The interfering substance is included to mimic real-world suspension conditions and challenge the disinfectant’s efficacy in the presence of organic matter.
- A sample of the disinfectant product being tested is added to the prepared test suspension containing the virus and interfering substance. This mixture simulates the conditions where the disinfectant would come into contact with the viruses on a veterinary area.
- After the designated contact time (mentioned in the protocol), the suspension is neutralizer solution. The neutralizer halts the action of the disinfectant to prevent it from continuing to kill or inactivate the virus beyond the prescribed contact time.
- A sample of the neutralizer solution that was in contact with the treated suspension is collected. This sample contains the neutralized disinfectant and any residual viruses that might have survived the disinfection process.
- The collected sample is then plated onto appropriate growth media and incubate under suitable conditions. This step allows any remaining viable viruses to replicate and form colonies if they have survived the disinfection process.
- After the incubation period, the number of viral colonies or absence thereof is counted and compared to the control samples. This comparison helps determine the virucidal efficacy of the disinfectant against the specific virus under test conditions.
This rigorous testing procedure helps assess the virucidal efficacy of the disinfectant according to EN14675 standard, providing valuable information about your technical competence in developing this standardized methodology.
- Al results should be including into the data sheet results collection sent together with the protocol and must be sent to us to study your results together with the others participant.
PARTICIPATION PERFORMANCE IN THE VIRUCIDAL ACTIVITY
The objective of proficiency testing is to perform an evaluation of laboratory performance by comparing results. For the analysis of the data, assumptions were considered to draw consistent conclusions from the results.
The statistical treatment was performed according to ISO 13528:2015. “Statistical methods for use in proficiency testing by interlaboratory comparisons“.
The method for estimating the assigned value was defined and approved by the specialized commission.
Just before the statistical treatment, an exploratory data analysis was performed according to the following criteria:
- Traceability of the provided result (checking of the sample identification number).
- Integrity (through scheduled Audit Trail logging).
- Visual (expression of the result, data input error).
- Technical (according to EN 14675 virucidal activity in veterinary area (Test method and requirements, phase 2/step 1).
- Statistical analysis (hypothesis testing, observed distributions, outliers’ detection).
DETERMINATION OF THE ASSIGNED VALUE
We used the Algorithm A described in Appendix C of ISO 13528 was used to obtain robust estimators of the mean and standard deviation. This robust mean was the reference value used to calculate the score of the laboratories. For this purpose, a slightly modified version of the algA() function from the metRology package (Ellison. 2018) of R was used. The validity of this function was tested in two ways:
- The source code of this function executes the algorithm in the Standard (with more precise calculations).
- The estimates made with the function on the data of example E.3 of the standard match with those indicated in the example itself.
The function returns the estimates of x^*=x_pt and s^*=σ_pt, and the uncertainty u(x_pt) was calculated following section 7.7.3 of ISO 13528, as the assigned value is derived from a robust estimator:
u(x_pt )=1,25⋅s^*/√p,
where p is the number of laboratories. The extended uncertainty is U(x_pt )=2u(x_pt ).
Z-SCORE EVALUATION
The Z-scores were also calculated for each laboratory using the following formula:
z_i=(x_i-x_pt)/σ_pt ,
where x_pt y σ_pt are the assigned values estimated previously with algorithm A (see section 7.1). According to the standard, values beyond 3 indicate unsatisfactory performance and values between 2 and 3 would be considered an alarm signal due to questionable performances.
It should be noted that for phase II, when participant’s results were logR < X or logR > X, the value of X was used for the calculation of reference values and Z-scores.
✅ Z-score ≤ 2.0 indicates satisfactory performance and generates no signal.
🤔 2.0 < Z-score < 3.0 indicates questionable performance and generates a warning signal.
❗ Z-score ≥ 3.0 indicates unsatisfactory performance and generates an action signal.
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