We read with interest the article published by De la Matta et al.,1 who concluded that the value of indiscriminate preoperative reverse transcription-polymerase chain reaction (RT-PCR) screening for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is questionable in identifying asymptomatic carriers. Although this conclusion is based on evidence that none of the 4520 preoperative RT-PCR tests performed at the local level yielded a positive result, several additional aspects should be considered when interpreting negative RT-PCR test results. Firstly, in contradiction to the authors who stated that the diagnostic sensitivity of RT-PCR is up to 95% in diagnosing SARS-CoV-2 infection, lines of evidence confirm that the rate of positive results from a single RT-PCR test by nasopharyngeal swab is around 85%, increasing to more than 95% when the sample is collected and tested a third time.2 An additional source of uncertainty is the high risk of false negative RT-PCR tests during the early stage of SARS-CoV-2 infection (typically 3–5 days after exposure to the virus), which can be as high as 50%.3 Inadequate secretion collection due to poor technique may also mean swabs fail to reach the nasopharynx, thereby increasing false negative rates and underestimating the prevalence of SARS-CoV-2 infection.4 The above factors could result in a significant number of patients being erroneously considered "negative" and subsequently developing active SARS-CoV-2 infection, with a high potential to spread the virus and thus generate in-hospital outbreaks. Finally, the diagnostic yield of molecular tests is considerably lower in presymptomatic/asymptomatic patients than in symptomatic patients, with a decrease in sensitivity from 96% to 70%, thus magnifying the risk of false negative tests in subjects infected with SARS-CoV-2 in the presymptomatic stage or in asymptomatic carriers. Since De la Matta et al. did not undertake any follow-up testing after the initial test, it seems unrealistic to conclude that the proportion of asymptomatic carriers among surgical patients would be "<1/2722", as they claim.1
Although we agree that widespread screening for SARS-CoV-2 in asymptomatic populations is unnecessary, and perhaps unwarranted for a variety of social, economic, and diagnostic reasons,5 we disagree with the conclusion that the rate of asymptomatic surgical patients is always negligible in low prevalence scenarios, especially when combined with a highly vulnerable setting. Efficient testing protocols are essential to reduce in-hospital outbreaks and protect the most vulnerable patients (i.e., the immunocompromised and elderly), and may be critical given the rapid spread of new SARS-CoV-2 variants of concern (VOC).
Conflict of interestsThe authors have no conflict of interests to declare.
