Is SARSCoV-2 nasopharyngeal swab still a gold standard in children?

SARSCoV-2 is the virus responsible for the known world pandemic, which is worrying the highest international authorities [1], [2]. The SARSCoV-2 genome was sequenced very early in the outbreak [1], [2], [4], [3]. Currently, World Health Organization (WHO) recommends real-time reverse transcriptase–polymerase chain reaction (rRT-PCR) respiratory samples (i.e. nasopharyngeal and oropharyngeal swabs or sputum and/or endotracheal aspirate or bronchoalveolar lavage in patients) for suspicious cases [5].

However, in the adult the swab can give a false negative result if performed in the very early stages or in the late disease stage [6], [7], [8]. For the child nasopharyngeal and oropharyngeal swabs for suspicious cases is strongly in doubt and there are no evidences to support it as golden test.

The tests for IgG and IgM antibodies dosage are reliable and rapid tests, but they have limits of sensitivity and specificity that do not currently allow their use for disease diagnosis. Furthermore, because a new virus and in many respects still unknown, it is not certain known about the time needed to develop antibodies of the acute phase (IgM) [9].

We report the experience of our pediatric SARSCoV-2 center. From March 16th to May 16th, fifty-five children with suspected SARSCoV-2 or positive swab were hospitalized. The rRT-PCR nasopharyngeal swab used is with an analytical sensitivity of 100 copies/template. Among 55 children, six (10.9%) had been sent for positive nasopharyngeal swab performed for sudden fever and lack of appetite in positive family. Obtained informed consent, nasopharyngeal swab were collected after 24 h from previous one and resulted negative. In 5 of 6(83.3%), cough appeared and they underwent chest x-ray negative for pnumopathy. Subsequently for clinical worsening and dyspnea appearance a chest CT scan was performed which showed bilateral pneumonia compatible with SARSCoV2 (Fig. 1 ).

Fig. 1

Pediatric SARSCOV2 and rapid swab negativity.

These preliminary data support the suggestion that nasopharyngeal swab is not the gold standard for diagnosis in children. The low affinity and volatility of the virus to the little expressed ACE2 receptors in the child could explain the rapid negativity of the swab. An accurate, easy and quick test is needed, to identify infected subjects and especially asymptomatic carriers, such as children. The specific antibody dosage for the virus could be a good diagnostic choice. The SARSCoV-2 swab is effective in adults but not in children, probably for the above reasons of low susceptibility to the infection. To our knowledge, there are no studies regarding the low sensitivity and specificity of the nasopharyngeal swab in children. In conclusion, our study suggests that nasopharyngeal and/or oropharyngeal swab may not suitable to confirm SARSCoV-2 infection in children.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.