Emerging evidence suggests a small decline in the effectiveness of vaccines against severe COVID-19 disease and death and a decline in preventing mild disease or infection, the head of the World Health Organization (WHO) said on Tuesday.
"The emergence of Omicron has prompted some countries to roll out COVID-19 booster programs for their entire adult populations, even while we lack evidence for the effectiveness of boosters against this variant," WHO Director-General Tedros Adhanom Ghebreyesus also told an online briefing.
"WHO is concerned that such programs will repeat the COVID-19 vaccine hoarding we saw this year, and exacerbate inequity. It's clear that as we move forward, boosters could play an important role, especially for those at highest risk of severe disease death," he added.