Johnson & Johnson received FDA emergency use authorization late Saturday for its coronavirus vaccine, which is recommended in a single dose for adults aged 18 years and older. Not only is the need for a booster injection eliminated, but the new vaccine also will not have to remain frozen until use.

New analyses by FDA and Johnson & Johnson demonstrate that the company's single-dose vaccine has overall efficacy of 72% against COVID-19 in the United States and 86% efficacy against severe cases of the disease. Efficacy was slightly lower in South Africa, which is in the grips of a mutated strain of the virus.

FDA said Monday that it will expedite efforts to gauge the efficacy of coronavirus vaccines against emerging strains.

New data from CDC indicate that vaccination rates among Medicare beneficiaries declined during the COVID-19 public health emergency starting in March 2020.

While still hopeful that the country will return to some level of normalcy by the end of 2020, President Biden conceded Friday that the emergence of new coronavirus strains and continued logistical hurdles could push the timeline back.