Prescription mouthwash cuts viral load in saliva; mRNA vaccines cut risk of asymptomatic COVID-19

The following is a roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for COVID-19, the illness caused by the virus.

Prescription mouthwash cuts viral load in saliva

A commercially available prescription mouthwash can decrease the amount of the coronavirus in saliva in adults with asymptomatic or mild COVID-19, helping to reduce their contagiousness, researchers found.

They randomly assigned 154 volunteers, all of whom had been diagnosed within the past week, to rinse three times a day for seven days with a mouthwash containing antiviral beta-cyclodextrin and citrox or a placebo.

Four hours after the first use of the antiviral mouthwash, salivary viral load was already significantly reduced, the researchers reported on Wednesday in a paper posted on the preprint server Research Square ahead of peer review.

During seven days of treatment, the mouthwash had a particularly beneficial effect on reducing the amount of virus in saliva in patients with high or very high levels to start with, the authors said.

"A one-minute rinse with a beta-cyclodextrin and citrox mouthwash reduces the SARS-CoV-2 salivary viral load by 70%" in asymptomatic or mildly ill adults, said coauthor Dr. Florence Carrouel of University Lyon in France.

"Thus, this mouthwash is a barrier measure against the spread of COVID-19."

mRNA vaccines cut risk of asymptomatic COVID-19

Ten days after receiving a second dose of the messenger RNA (mRNA) vaccines from Pfizer/BioNTech or Moderna, people without COVID-19 symptoms are far less likely to be carrying the virus and unknowingly spreading it, compared with people who have not been vaccinated, according to Mayo Clinic doctors.

Their data, published on Wednesday in Clinical Infectious Diseases, come from 39,000 patients who were routinely tested for COVID-19 before undergoing various medical procedures.

More than 48,000 screening tests were performed, including 3,000 on patients who had received at least one dose of an mRNA vaccine.

Among individuals who had received a single dose of vaccine at least 10 days earlier, they saw a 72% reduction in the risk of a positive COVID-19 test.

After adjusting for a range of factors, they found an 80% risk reduction of testing positive for COVID-19 among people without symptoms who had gotten both doses.

The authors said their findings underscore the fact that messenger RNA vaccines for COVID-19 can help to significantly limit the spread of the virus by people without symptoms. -- Reuters