42 CFR § 493.919 - Virology.
(a) Program content and frequency of challenge. To be approved for proficiency testing for virology, a program must provide a minimum of five samples per testing event. There must be at least three testing events at approximately equal intervals per year. The samples may be provided to the laboratory through mailed shipments. The specific organisms included in the samples may vary from year to year.
(1) The annual program must include, as applicable, samples for:
(i) Viral antigen detection; and
(ii) Detection and identification of viruses.
(2) An approved program must furnish HHS and its agents with a description of the samples it plans to include in its annual program no later than 6 months before each calendar year. The program must include other important emerging viruses and viruses commonly occurring in patient specimens.
(3) The content of an approved program must vary over time, as appropriate. If appropriate for the sample sources, the types of viruses included annually must be representative of the following major groups of medically important viruses:
(i) Respiratory viruses;
(ii) Herpes viruses;
(iii) Enterovirus; and
(iv) Intestinal viruses.
(b) Evaluation of laboratory's performance. HHS approves only those programs that assess the accuracy of a laboratory's response in accordance with paragraphs (b)(1) through (6) of this section.
(1) The program determines the viruses to be reported by direct viral antigen detection, and detection and identification of viruses. To determine the accuracy of a laboratory's response, the program must compare each response with the response which reflects agreement of either 80 percent or more of 10 or more referee laboratories or 80 percent or more of all participating laboratories. Both methods must be attempted before the program can choose to not grade a PT sample.
(2) A laboratory must detect and identify the viruses to the highest level that the laboratory reports results on patient specimens.
(3) A laboratory's performance will be evaluated on the basis of the average of its scores for paragraphs (b)(4) through (5) of this section as determined in paragraph (b)(6) of this section.
(4) The performance criterion viral antigen detection is the presence or absence of the viral antigen. The score is the number of correct responses divided by the number of samples to be tested, multiplied by 100.
(5) The performance criterion for the detection and identification of viruses is the total number of correct responses for viral detection and identification submitted by the laboratory divided by the number of viruses present plus the number of incorrect virus reported by the laboratory multiplied by 100 to establish a score for each sample in each testing event. Since laboratories may incorrectly report the presence of viruses in addition to the correctly identified principal organism(s), the scoring system must provide a means of deducting credit for additional erroneous organisms that are reported. For example, if a sample contained one principal organism and the laboratory reported it correctly but reported the presence of an additional organism, which was not considered reportable, the sample grade would be 1/(1+1) × 100 = 50 percent.
(6) The score for a testing event is the average of the sample scores as determined under paragraphs (b)(4) and (5) of this section.