1. World Health Organization. WHO coronavirus (COVID-19) dashboard. Available from: https://covid19.who.int Last accessed: July 18, 2022.
2. Waning antibody responses in asymptomatic and symptomatic SARS-CoV-2 infection;Choe;Emerg Infect Dis,2021
3. Centres for Disease Control and Prevention. COVID-19 Risks and Vaccine Information for Older Adults. Available from: https://www.cdc.gov/aging/covid19/index.html Last accessed: September 25, 2023.
4. The vaccine efficacy against the Sars-Cov-2 Omicron: A systemic review and meta-analysis;Zou;Front Public Health,2022
5. UK Health Security Agency. COVID-19 vaccine surveillance report Week 16. Available from: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1070356/Vaccine-surveillance-report-week-16.pdf Last accessed: September 30, 2022.