Table 4 Characteristics of included studies

Gottsauner [23]

Inclusion criteria:

Positive covid19 infected patients within the last 72 h in a hospital

Exclusion criteria:

Patients who need intubation or mechanical ventilation or severe stomatitis

1 to 5 days (median 3 days)

12 patients (6 female and 6 male) had a median age of 55 years (range: 22–81 years). Two with neg. RT-PCR test

RT-PCR test of oropharyngeal specimens

Mohamed [24]

Inclusion criteria:

Adults older than 18 years, COVID-19 positive patients with no symptom, less than five days from diagnosis

Exclusion criteria:

Objects who cannot understand instructions, express symptoms of covid-19 infection such as fever or respiratory problems or, abnormal chest computed tomography, patients started treatments for covid-19, objects infected with SARS-CoV-2 again, thyroid dysfunction, allergy to povidone-iodine

Age range from 22–56 years old (16 male,4 female)

RT-PCR test was performed on nasopharyngeal and oropharyngeal swabs targeting the E gene and RNA-dependent RNA polymerase gene (RdRP) and provided with a cycle threshold (ct) value

Mukhtar [25]

Inclusion criteria:

Patients with positive PCR test for covid-19 through combined Nasopharyngeal Oropharyngeal swab who were hospitalized within 24 h

Exclusion criteria:

Objects under 18 years of age, mental or cognitive problems, pregnant women, head and neck injuries, patients who need intubation

The mean age was 49; the age range had no significant difference between the objects (P = 0.89). Number of males were higher (72 vs. 10)

Intervention group (n = 46):

1 non-COVID Pneumonia (NCP) Asymptomatic; 11 NCP mild symptoms; 24 MILD COVID Pneumonia (CP); 1 moderate CP; 9 severe CP

Control group (n = 46):

4 NCP Asymptomatic; 10 NCP mild symptoms; 18 mild CP; 3 moderate CP; 11 severe CP

RT-PCR test of nasopharyngeal and oropharyngeal swabs targeting the S, N and E-genes

Obtaining CT value > 30 in subsequent covid-19 RT-PCR test

Lamas [26]

Inclusion criteria:

Not mentioned

Exclusion criteria:

Not mentioned

74, 73, 43, 54 years old patients (28–41 days after positive nasopharyngeal positive test);

2 Males and 2 females

rRT-PCR assay which targeted E-gene, RdRP and N genes

Yoon [27]

Inclusion criteria:

Not mentioned

Exclusion criteria:

Not mentioned

Two hospitalized patients diagnosed with covid-19

rRT-PCR which targeted the E and RdRP genes of SARS-CoV-2

Cts were derived from supplementary tables

Seneviratne

[28]

Inclusion criteria:

Patients whos their nasal swabs were positive for rRt-PCR assay of SARS-COV-2 from a hospital in Singapore

Exclusion criteria:

thyroid problems, patients received radioactive iodine lately, under treatment with lithium, pregnant women, and renal failure 19 pts had negative PCR for saliva and one patient excluded due to non-compliance

All were males except 1 in control group

The in-house RT-PCR test of saliva samples targeting the E gene of SARS-CoV-2

[Fold changes in comparison to control group also are reported in the article but we omit them as not reported in other studies.]

Carrouel [29]

Inclusion criteria:

Adults aged 18to 85 years old with a clinical diagnosis of COVID-19 infection, asymptomatic or mild clinical symptoms that had been present for < 8 days

Exclusion criteria:

Pregnancy, breastfeeding, an inability to comply with the protocol, a lack of written agreement, mouthwash use on a regular basis (more than once a week), an inability to answer questions and a lack of cooperation

who had voluntarily presented at the hospital for a screening qualitative PCR test. Asymptomatic patients are defined as individuals without clinical signs whereas mild corresponds to outpatients and patients with clinical symptoms without pneumonia manifestations on image results

Quantitative RT-PCR

(Data are expressed in log10 copies/mL of saliva or in % for the % of variation calculated with values expressed in log10 copies/mL.)

Eduardo [30]

Inclusion criteria:

Age of 18–90 years

- Length of hospitalization up to 3 days

- Previously identified to be positive for SARS-CoV-2 as determined by nasal swabbing and qRT-PCR

- Adequate performance in the use of the different types of mouthwash

- Adequate performance of oral hygiene

Exclusion criteria:

No detection of SARS-CoV-2 by qRT-PCR at the time of recruitment

- Hospitalized in intensive care units

- Lesions in the oral mucosa

- Bleeding in the oral cavity that prevented the collection of samples

- History of allergy, irritations, or other side effects of the use of the test substances

- Use of the test substances or other oral antimicrobials 48 h before the baseline collection

- Non-adherence to the established protocol or inability to perform planned procedures

Patients hospitalized in negative-pressure rooms at the Hospital Israelita Albert Einstein (HIAE), Brazil, between June 2020 and July 2020,

Amplification of the SARS-CoV-2 N and ORF1ab genes was performed using a commercial COVID-19 qRT-PCR kit

Chaudhary [31]

Inclusion criteria:

Adults age 21–80 admitted to The Ohio State University Wexner Medical Center with a diagnosis of COVID-19 confirmed by Polymerase Chain Reaction (PCR) for symptomatic group and (2) absence of any COVID-19 screening symptoms (based on the ADA questionnaire and body temperature) for the asymptomatic, pre-symptomatic and post-symptomatic groups

Exclusion criteria:

(1) Allergy to any study mouth rinse, (2) active uncontrolled thyroid disease, (3) pregnancy and (4) patients undergoing radioactive iodine therapy

Patients categorized to 4 groups:

Asymptomatic, presymptomatic, post symptomatic

SARS-COV-2 N1, N2 genes were targeted