Click here to read about Buccal swabs alone insufficient to screen for SARS-CoV-2 in children.

Saliva is not a useful specimen for diagnosing COVID-19 in children, a review1 by KK Women’s and Children’s Hospital (KKH) has found.

 

​Key findings:

  • Laboratory RT-PCR testing of nasopharyngeal and saliva specimens from 18 children with COVID-19 revealed a peak saliva sensitivity of 52.9% compared to nasopharyngeal swabs.
  • In five patients, saliva specimens persistently tested negative for SARS-CoV-2. In another five patients, saliva that initially tested negative on days one to three, turned positive on days four to seven.
  • Saliva had a generally higher cycle threshold value compared to nasopharyngeal swabs. This may indicate that saliva specimens contain a lower amount of viral RNA than nasopharyngeal swabs
  • While saliva specimens have shown promise for diagnosing COVID-19 in adults, with some studies showing a peak sensitivity of 96%, the utility of saliva specimens in children is low. Saliva is not a useful specimen for diagnosing COVID-19 in children

 

Low Sensitivity of Saliva Specimens in Children

Paired nasopharyngeal and saliva specimens were taken from 18 children with laboratory-confirmed SARS-CoV-2, the virus that causes COVID-19. Laboratory testing via real-time reverse transcription-polymerase chain reaction (RT-PCR) revealed a peak saliva sensitivity of 52.9 per cent compared to nasopharyngeal swabs.

A previous KKH study on buccal swab specimens measured a peak sensitivity of 71.4 per cent.

“While saliva specimens have shown promise for diagnosing COVID-19 in adults, with some studies showing a peak sensitivity of 96 per cent, the utility of saliva specimens in children is low, with a peak sensitivity of only 52.9 per cent,” shares corresponding author, Associate Professor Chong Chia Yin, Senior Consultant, Infectious Disease Service, KKH.

In five patients, saliva specimens persistently tested negative for SARS-CoV-2. In another five patients, saliva that initially tested negative on days one to three, turned positive on days four to seven.

“Interestingly, the laboratory RT-PCR tests showed that saliva had a generally higher cycle threshold value compared to nasopharyngeal swabs. This may indicate that saliva specimens contain a lower amount of viral RNA than nasopharyngeal swabs,” adds Assoc Prof Chong.

Within the patient cohort, while there were no age or cycle threshold differences between symptomatic (12) and asymptomatic (8) patients, male patients had higher saliva cycle threshold values on days one to three, compared to female patients.

Read the full study here.

 

​Reference:

  1. Chong CY, Kam KQ, Li JH, et al. Saliva is not a useful diagnostic specimen in children with Coronavirus Disease 2019, Clinical Infectious Diseases, ciaa1376, https://doi.org/10.1093/cid/ciaa1376

 

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