More fear than harm.
The 350 students from the Oisellerie de La Couronne high school, near Angoulême, will finally return to their classes on Monday.
The establishment had to close its doors on Tuesday for fear of an outbreak of contamination, but many results of antigenic tests turned out to be false positives.
The questions arose after a screening operation with these rapid tests which ended with an "atypical result" raising fears of a massive cluster, the Charente prefecture explained in a press release on Friday.
Of the 250 volunteers tested on March 9, 119 tested positive.
An abnormally high rate which, after verification, does not allow "to exclude the use of a stock of defective tests due to inadequate storage methods", specifies the prefecture.
The panic was therefore short-lived for the adolescents and their parents.
The students and teachers presumed positive were then led to carry out the reference nasopharyngeal test, by the RT-PCR method, and the first results confirm the “atypical nature” of the first session: out of the 73 tests already analyzed, 100 % are negative.
Unsuitable storage conditions?
Why such a lag?
An expertise was entrusted to the pharmacists of the Regional Health Agency (ARS) Nouvelle-Aquitaine to try to explain this high rate of "false positives".
While awaiting “conclusions”, the ARS “hypothesizes” that the storage conditions required by the manufacturer to keep the tests (“between 2 and 30 ° C”) are unsuitable.
“The storage temperatures in the high school gymnasium never dropped below 10 ° C and were therefore in line with what was requested.
It remains to be seen whether the recommended temperatures are the right ones, ”underlined Martine Liège, deputy director of ARS in Charente.
By way of comparison, she adds that "the same batch of tests was administered in another high school", this time without giving rise to abnormal results.
In December, the group of medical analysis laboratories Biogroup questioned the reliability of antigenic tests, deemed to be less sensitive than RT-PCR tests, stressing that their results included not only “false negatives” but also “false negatives”. positive ”.
Of 1327 presumed negative, 111 were in fact positive.
But above all, 214 of the 339 positive (or 63%) were negative, had found Biogroup in its study.
