* pediatric patients, t * hose who tested negative for sars-cov-2 by the rt-pcr method at the time of recruitment or at the time of first oral fluid and saliva collection; * those who exhibit oral ulcerations and other erosive lesions in the oral mucosa, which contraindicate the use of cetylpyridinium; * patients who have bleeding in the oral cavity which prevents sample collections; patients who report history of allergy, irritations or other side effects derived from the use of these substances; * patients who do not adhere to oral care protocols or those in whom it was not possible to perform these procedures.

* pediatric patients, t * hose who tested negative for sars-cov-2 by the rt-pcr method at the time of recruitment or at the time of first oral fluid and saliva collection; * those who exhibit oral ulcerations and other erosive lesions in the oral mucosa, which contraindicate the use of cetylpyridinium; * patients who have bleeding in the oral cavity which prevents sample collections; patients who report history of allergy, irritations or other side effects derived from the use of these substances; * patients who do not adhere to oral care protocols or those in whom it was not possible to perform these procedures.

- pediatric patients, t - hose who tested negative for sars-cov-2 by the rt-pcr method at the time of recruitment or at the time of first oral fluid and saliva collection; - those who exhibit oral ulcerations and other erosive lesions in the oral mucosa, which contraindicate the use of cetylpyridinium; - patients who have bleeding in the oral cavity which prevents sample collections; patients who report history of allergy, irritations or other side effects derived from the use of these substances; - patients who do not adhere to oral care protocols or those in whom it was not possible to perform these procedures.

- pediatric patients, t - hose who tested negative for sars-cov-2 by the rt-pcr method at the time of recruitment or at the time of first oral fluid and saliva collection; - those who exhibit oral ulcerations and other erosive lesions in the oral mucosa, which contraindicate the use of cetylpyridinium; - patients who have bleeding in the oral cavity which prevents sample collections; patients who report history of allergy, irritations or other side effects derived from the use of these substances; - patients who do not adhere to oral care protocols or those in whom it was not possible to perform these procedures.

- pediatric patients, those who tested negative for sars-cov-2 by the rt-pcr method at the time of recruitment or at the time of first oral fluid and saliva collection; those who exhibit oral ulcerations and other erosive lesions in the oral mucosa, which contraindicate the use of cetylpyridinium; patients who have bleeding in the oral cavity which prevents sample collections; patients who report history of allergy, irritations or other side effects derived from the use of these substances; patients who do not adhere to oral care protocols or those in whom it was not possible to perform these procedures.

- pediatric patients, those who tested negative for sars-cov-2 by the rt-pcr method at the time of recruitment or at the time of first oral fluid and saliva collection; those who exhibit oral ulcerations and other erosive lesions in the oral mucosa, which contraindicate the use of cetylpyridinium; patients who have bleeding in the oral cavity which prevents sample collections; patients who report history of allergy, irritations or other side effects derived from the use of these substances; patients who do not adhere to oral care protocols or those in whom it was not possible to perform these procedures.