LOS ANGELES, May 23 (Xinhua) -- Pfizer and its German partner BioNTech said Monday that preliminary clinical data showed their three-dose COVID-19 vaccine regimen was 80 percent effective for children 6 months to 5 years old at preventing illness during the Omicron wave.

       The vaccine was found to elicit a strong immune response following a third dose, and was well tolerated by the kids with a majority of the side effects mild to moderate, according to the companies.

       The safety data for the Pfizer vaccine is based on 1,678 children under age 5 who received a third shot at least two months after the second dose when Omicron was the main variant in circulation.

       Kids under age 5 receive 3-microgram shots, one-tenth the dosage level for adults.

       "These topline safety, immunogenicity and efficacy data are encouraging, and we look forward to soon completing our submissions to regulators globally with the hope of making this vaccine available to younger children as quickly as possible, subject to regulatory authorization," said Pfizer Chairman and CEO Albert Bourla.

       Pfizer said it is preparing relevant documents and expect completing the submission process to the U.S. Food and Drug Administration this week.