The approval of a Covid-19 vaccine by the end of the year should lead to much of the United States being vaccinated during the first half of 2021, according to Goldman Sachs.

On Thursday, the firm’s economic research team laid out a timeline for mass immunization with a successful vaccine, which included many high-risk individuals receiving their shots during the first quarter.

“While the path ahead is likely to be bumpy, we expect mass immunization to largely complete the reopening process and trigger a reacceleration next spring that will leave full-year growth well above expectations,” Goldman said in a note to clients.

The firm estimated that the first 45 million vaccines would go to the highest-risk individuals in the first three months of the year. Other older Americans and those with comorbidities would begin to be vaccinated in April, with the rest of the population, including younger people, being vaccinated in May and June.