The research arm of Citigroup has assessed that the economic benefits of COVID-19 vaccinations may not begin to show until late 2021, when the start of "herd immunity" is expected.

Herd immunity occurs when enough people in a population develop protection against a disease that it can no longer spread easily.

Citi Research assumed that the vaccine candidates of Pfizer-BioNTech and Moderna, both with preliminary efficacy rates of around 95 percent, and that of Oxford-AstraZeneca at 70 percent, would receive emergency approvals between next month and January 2021.

The report forecast that vaccinations could raise global economic growth by point-seven percentage points in 2021, and three percentage points in 2022 as economic activity returns to normal.

While normalized activity will likely raise growth in developed markets by one-point-two and three-point-nine percentage points in 2021 and 2022, respectively, emerging markets are expected to see growth increase by point-one and two percentage points.

The report added that this was partly because some countries have already contained the virus and vaccine distribution may take longer to reach emerging countries.