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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.

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.