COVID-19 Resource Center

COVID-19 Resource Center

Perspective from Amesh A. Adalja, MD

Press conference.

Disclosures: Murthy, Nanduri, Rosenberg, Ryan, Swaminathan, Tedros, Tenforde and Zients report no relevant financial disclosures. Please see the studies for all other authors’ relevant financial disclosures.
August 18, 2021
3 min read

US to offer booster shots to fully vaccinated Americans starting Sept. 20

Perspective from Amesh A. Adalja, MD

Press conference.

Disclosures: Murthy, Nanduri, Rosenberg, Ryan, Swaminathan, Tedros, Tenforde and Zients report no relevant financial disclosures. Please see the studies for all other authors’ relevant financial disclosures.
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The United States will begin offering third doses of COVID-19 vaccine to fully vaccinated Americans beginning Sept. 20, Biden administration officials announced Wednesday.

People will be able to receive a third dose of the Pfizer-BioNTech or Moderna messenger RNA vaccines beginning 8 months after the date they received their second shot.

COVID vaccine stock image
Source: Adobe Stock.

The plan, which comes amid a surge in cases caused by the delta variant and some evidence of waning protection from the vaccines, is contingent on the FDA authorizing booster doses and the CDC signing off on recommendations for their use, U.S. Surgeon General Vivek H. Murthy, MD, said during a press briefing.

“It will be just as easy and convenient to get a booster shot as it is to get a first shot today,” White House COVID-19 response coordinator Jeff Zients said.

Murthy said data are still forthcoming on the Johnson & Johnson vaccine but that people who received that shot are also expected to need a booster.

Rochelle P. Walensky
Anthony S. Fauci

CDC Director Rochelle P. Walensky, MD, MPH, and National Institute of Allergy and Infectious Diseases Director Anthony S. Fauci, MD, described the U.S. data that influenced the booster plan, including three new MMWR reports that were released during the press briefing.

“Vaccine effectiveness is generally decreased against the delta variant,” Walensky said.

‘The haves and have-nots’
The U.S. booster plan has taken shape just weeks after WHO Director-General Tedros Adhanom Ghebreyesus, PhD, MSc, called for a moratorium on booster shots in wealthy countries until at the least the end of September to improve global vaccine equity.

World health leaders reiterated that appeal with even stronger language on Wednesday, a day after details of the U.S. plan leaked in the media.

“We’re planning to hand out extra life jackets to people who already have life jackets while we’re leaving other people to drown without a single life jacket,” Mike Ryan, MD, MPH, director of WHO’s Health Emergencies Program, said during a press briefing.

Tedros Adhanom Ghebreyesus

Tedros said 10 countries have used 75% of the global COVID-19 vaccine supply, whereas just 2% of people living in low-income countries have been vaccinated. Lower income countries, he said, “have not even been able to vaccinate their health care workers and at-risk communities and are now experiencing large spikes.”

Although he noted that the U.S. is the largest sharer of vaccine doses globally — 115 million doses to 80 countries, according to Zients — Tedros reiterated his disapproval of the kind of booster program now being planned by the Biden administration.

“The divide between the haves and have-nots will only grow larger if manufacturers and leaders prioritize booster shots over supply to low- and middle-income countries,” he said during the briefing. “The virus is evolving and it’s not in the best interest of leaders just to focus on narrow nationalistic goals when we live in an interconnected world and the virus is mutating quickly.”

He also said he was “stunned” by a New York Times report that Johnson & Johnson vaccine doses packaged in South Africa are being shipped to Europe, “where virtually all adults have been offered vaccines at this point,” and urged the drug maker to distribute the vaccines in Africa first.

“To overcome these fragile times, we must do better at sharing resources and health tools,” he said. “Our mutual resilience is only as strong as our weakest bond. Vaccine injustice is a shame on all humanity, and if we don’t tackle it together, we will prolong the acute stage of this pandemic for years when it could be over in a matter of months.”

Decreased protection against delta
Data reported by Eli S. Rosenberg, PhD, an associate professor of epidemiology and biostatistics at the University of Albany, and colleagues in one of the new MMWR reports showed a decrease in the overall age-adjusted vaccine effectiveness for adults in the state of New York from 91.7% to 79.8% during a 12-week period from May 3 to July 25 in which the proportion of cases in the region caused by the delta variant increased from less than 2% to over 80%.

However, data also showed that the overall age-adjusted effectiveness against hospitalization among vaccinated adults in the state was “relatively stable” at between 91.9% and 95.3%, Rosenberg and colleagues reported.

In another report, Mark W. Tenforde, MD, PhD, MPH, a medical epidemiologist at the CDC on the CDC COVID-19 Response Team, and colleagues assessed the duration of vaccine effectiveness among 3,089 adults hospitalized in 18 states from March 11 through July 14.

Among those who received an mRNA vaccine, effectiveness against COVID-19 hospitalization was 86% (95% CI, 82%-88%) overall and 90% (95% CI, 87%-92%) among adults who are not immunocompromised during the entire surveillance period, Tenforde and colleagues reported.

Vaccine effectiveness declined from 86% (95% CI, 82%-90%) 2 to 12 weeks after receiving the second dose to 84% (95% CI, 77%-90%) 13 to 24 weeks later.

“These data confirm that while protection against infection may decrease over time, protection against severe disease and hospitalization is currently holding up pretty well,” Walensky said during the briefing.

The analysis by Tenforde and colleagues also found that vaccine effectiveness against COVID-19 hospitalization among patients with immunocompromising conditions was much lower at 63% (95% CI = 44%-76%). This population has already been authorized to receive a third COVID-19 vaccine shot.

Another analysis of mRNA vaccine effectiveness by CDC epidemiologist Srinivas Nanduri, MD, and colleagues from the CDC COVID-19 Response Team showed a decline in vaccine effectiveness among nursing home residents from 74.7% (95% CI, 70%-78.8%) in a period stretching from March through May to 53.1% (95% CI, 49.1%-56.7%) in June and July, when the delta variant predominated.

“This represents a substantial decline in vaccine effectiveness against infection among those who are most vulnerable,” Walensky said. 


Nanduri S, et al. MMWR Morbid Mortal Wkly Rep. 2021;doi:10.15585/mmwr.mm7034e3.

Robbins R, Miller M. COVID vaccines produced in Africa are being exported to Europe. The New York Times. Accessed August 18, 2022.

Rosenberg ES, et al. MMWR Morbid Mortal Wkly Rep. 2021;doi:10.15585/mmwr.mm7034e1.

Tenforde MW, et al. MMWR Morbid Mortal Wkly Rep. 2021;doi:10.15585/mmwr.mm7034e2.