Last week, the WHO has also announced a plan to end the COVID-19 pandemic by ensuring all people, everywhere, have access to vaccines.
The National Health Service said people in the high-risk categories have been quick to take up the offer of the booster jabs ahead of winter, with a total of 2.08 million 'top ups' administered so far
President Joe Biden got his first shot on December 21 and his second dose three weeks later, on January 11, along with his wife, Jill Biden.
The spike in demand -- expected following last week's federal recommendation on booster shots -- would be the first significant jump in months.
The booster plan marks an important shift in the nation's vaccination drive. Britain and Israel are already giving a third round of shots over strong objections from the World Health Organization
People can get the shot on condition a minimum six-month period has passed since they got fully vaccinated with the Pfizer or Moderna vaccine.
Study will provide data on level of immunity, interval between doses, necessity of booster dose
WHO calls for 'moratorium' on COVID boosters until at least Sept-end to address vaccination disparity
Ghebreyesus said ensuring increased vaccination coverage in low-income countries requires everyone's cooperation.
A booster shot will also be offered to anyone who received the two-dose AstraZeneca or single-dose Johnson & Johnson vaccines.
The plan also recommends promoting vaccination for those aged 12-17, which would go further than earlier guidance issued by the country's vaccine regulator.