Lack of glove modifications at COVID-19 testing facilities in Belgium led to main cross-contamination of samples and a excessive fee of false optimistic outcomes, analysis being offered at this yr’s European Congress of Scientific Microbiology & Infectious Illnesses (ECCMID) in Lisbon, Portugal, (23-26 April) has discovered.
The introduction of large-scale PCR testing for COVID-19 offered numerous logistical challenges, together with a shortage of personnel adequately educated to do nasopharyngeal swabbing.
Analysis from a government-funded lab in Belgium has recognized insufficient PPE administration in testing facilities as a supply of main cross-contamination.
Scientists on the COVID-19 Federal Platform, Division of Laboratory Medication UZ Leuven, Leuven, Belgium have been alerted to the issue in September 2021 once they seen that 70% of samples taken that day at a testing heart in Flemish Brabant, Flanders, had examined optimistic for COVID-19. The typical positivity fee on the time was round 5-10%.
90% of the optimistic samples had a really low viral load, which hinted that they’d been contaminated with the SARS-CoV-2 virus, reasonably than being true positives.
The sufferers’ outcomes have been instantly withheld and a root-cause evaluation (an investigation into the reason for the spike in optimistic samples) carried out.
After excluding lab contamination we organized the outcomes from that day in chronological order by time of pattern assortment.
We noticed that nobody had examined damaging after a pattern was collected from a affected person with a really excessive viral load and instantly contacted the take a look at heart.
This led to lack of glove-changing, together with high-paced pattern assortment by a brand new swabber and the breaking of a swab within the tube, being recognized because the doubtless supply of the contamination.
Protocols at this take a look at heart have been sharpened in a single day and all of the sufferers whose outcomes have been withheld have been recalled for a brand new pattern the subsequent day. 100% of them have been damaging.”
Bram Slechten, Lead Researcher
To evaluate the size of the issue, Mr Slechten and colleagues then retrospectively checked 4 months of outcomes (June-Sept 2021) of PCR exams from 11 testing facilities for false positives.
A suspected collection of contaminated samples was outlined at least of three weak optimistic samples (low viral load, <104 copies RNA/mL) after one optimistic pattern with a excessive viral load (>106 copies RNA/mL).
Additionally they visited the websites to evaluate the personnel.
The evaluation recognized potential cross-contamination occasions in 73% (8/11) of the take a look at facilities. The proportion of samples suspected of being wrongly reported as optimistic broadly diversified per day and per heart. The four-month common ranged from 0% to three.4% per testing heart.
The best variety of false positives at one testing heart on a single day was 77 (out of 382 exams) − 20% of individuals examined that day. (All of those sufferers got the chance to retest.)
Web site visits recognized lack of glove modifications between sufferers are being the supply of cross-contamination.
“If the employees did not change gloves between every affected person, it was virtually sure that contamination would happen,” says Mr Slechten. “We recognized 4 the reason why altering of gloves did not occur: it was merely not within the protocol; right protocol was in place but it surely was not adopted attributable to lack of coaching of latest members of employees; not having the precise dimension of glove accessible; work stress, some swabbers needed to pattern one affected person each two minutes.”
Extra rigorous PPE insurance policies have been put in place in any respect 11 testing facilities from the tip of October 2021, in response to the research’s outcomes.
This included managers being tasked with telling each employees member who swabbed sufferers in regards to the significance of glove altering and take a look at facilities being contacted if there was a spike of their false optimistic fee.
Observe-up of 1 take a look at heart revealed the affect. Earlier than the intervention, it had a day by day positivity fee of 11% and a median false positivity fee of three.4%. However often, the false optimistic fee rose to twenty%. After the intervention, the false optimistic fee fell to virtually zero.
The group at UZ-Leuven is constant to observe charges of false positives, to detect any remoted cross-contamination occasions.
As well as, Sciensano (the Belgian scientific institute for public well being) alerted all labs in Belgium to the difficulty in October 2021.
The researchers say that the majority of instances of cross-contamination have been detected in time to withhold the outcomes and recall the sufferers, that means the faulty outcomes weren’t given out. Some instances, nonetheless, went undetected, that means that on some days, a whole lot of sufferers obtained a mistaken outcome.
Mr Slechten says: “Nasopharyngeal sampling includes shut contact between the hand of the well being skilled, the affected person and pattern tube. Due to this fact, it’s important to vary gloves between every affected person.
“Within the context of high-throughput sampling, insufficiently educated employees needed to pattern excessive numbers of sufferers in a restricted time. This case led to a excessive stage of cross-contamination which had gone largely unrecognized, leading to false positives and other people self-isolating and taking break day work unnecessarily.
“Moreover, every false optimistic generates high-risk contacts who may additionally have to be examined, growing the burden for labs, testing facilities and contact tracing.”
He believes the false positives artificially inflated the COVID-19 case numbers for Belgium. He says: “It’s onerous to place a quantity on, nonetheless, as a result of we noticed a whole lot of variations between the take a look at facilities we studied. As well as, we solely checked out take a look at centres in a single a part of Belgium, making it onerous to get the entire image.
“It is rather possible that this additionally occurred in different international locations.
“Whereas I haven’t got detailed information of the protocols in testing facilities in different international locations, the main target is usually on potential occasions throughout the lab atmosphere. Nonetheless, our analysis gives an ideal instance of the significance of trying past the lab and keeping track of the whole testing chain.”
