... a vaccination strategy based on repeated booster doses of the original vaccine composition is unlikely to be appropriate or sustainable.
WHO Originaltext
https://www.rt.com/news/545733-who-vaccines-boosters-experts/
https://www.who.int/news/item/11-01-2022-interim-statement-on-covid-19-vaccines-in-the-context-of-the-circulation-of-the-omicron-sars-cov-2-variant-from-the-who-technical-advisory-group-on-covid-19-vaccine-composition