The immunogenicity of an extended dosing interval of BNT162b2 against SARS-CoV-2 Omicron variant among healthy school-aged children, a randomized controlled trial.

"Declaration of competing interest The authors have no competing interest to declare."

"Funding This study was supported by the National Vaccine Institute, Thailand (grant No. 2565.1/5). Vaccines used in this study were supported by the Department of Diseases Control, Ministry of Public Health, Thailand."

"This is an open-label, randomized clinical trial among healthy school-aged children. The study was conducted at six clinical research sites in Thailand: four sites in Bangkok (Chulalongkorn University, Ramathibodi Hospital, Siriraj Hospital Mahidol University, and Queen Sirikit National Institute of Child Health), one site in Khon Kaen (Khon Kaen University) and one site in Pathumthani (Thammasat University). The inclusion criteria were (i) healthy children aged 5-11 years and (ii) no history of COVID-19 vaccination. The exclusion criteria were participants who (ii) had a documented SARS-CoV-2 infection by anti-nucleocapsid (anti-N) test, (ii) have a history of anaphylaxis to any of the BNT162b2 vaccine components, (iii) received immunoglobulins or blood components within 3 months, and (iv) received inactivated vaccines 14 days or live attenuated vaccines 28 days before enrollment. Written informed consent was signed by the parents of all participants. Written assent was obtained from participants aged 7-11 years, and verbal assent was obtained from participants aged 5-<7 years. This study was registered at the Thai Clinical Trials Registry (TCTR20220125002) and ethically approved by the institutional review board (IRB) from each of the clinical research sites."