at a press briefing August 18.
Those who received the Pfizer-BioNTech and Moderna vaccines would be eligible to get a booster shot 8 months after they received the second dose of those vaccines, officials said. Information on boosters for those who got the one-dose Johnson & Johnson vaccine will be forthcoming.
“We anticipate a booster will [also] likely be needed,” said U.S. Surgeon General Vivek Murthy, MD. The J&J vaccine was not available in the U.S. until March, he said, and ‘’we expect more data on J&J in the coming weeks, so that plan is coming.”
The plan for boosters for the two mRNA vaccines is pending the FDA’s conducting of an independent review and authorizing the third dose of the Moderna and Pfizer-BioNTech vaccines, as well as an advisory committee of the CDC making the recommendation.
“We know that even highly effective vaccines become less effective over time,” Dr. Murthy said. “Having reviewed the most current data, it is now our clinical judgment that the time to lay out a plan for the COVID-19 boosters is now.”
Research released Aug. 18 shows waning effectiveness of the two mRNA vaccines.
At the briefing, Dr. Murthy and others continually reassured listeners that while effectiveness against infection declines, the vaccines continue to protect against severe infections, hospitalizations, and death.
“If you are fully vaccinated, you still have a high degree of protection against the worst outcomes,” Dr. Murthy said.
Data driving the plan
CDC Director Rochelle Walensky, MD, cited three research studies published Aug. 18 in the CDC’s Morbidity and Mortality Weekly Report that helped to drive the decision to recommend boosters.
Analysis of nursing home COVID-19 data from the CDC’s National Healthcare Safety Network showed a significant decline in the effectiveness of the full mRNA vaccine against lab-confirmed COVID-19 infection, from 74.7% before the Delta variant (March 1-May 9, 2021) to 53% when the Delta variant became predominant in the United States. The analysis during the Delta dominant period included 85,000 weekly reports from nearly 15,000 facilities.
Another study looked at more than 10 million New York adults who had been fully vaccinated with either the Moderna, Pfizer, or J&J vaccine by July 25. During the period from May 3 to July 25, overall, the age-adjusted vaccine effectiveness against infection decreased from 91.7% to 79.8%.
Vaccine effectiveness against hospitalization remains high, another study found. An analysis of 1,129 patients who had gotten two doses of an mRNA vaccine showed vaccine effectiveness against hospitalization after 24 weeks. It was 86% at weeks 2-12 and 84% at weeks 13-24.
Immunologic facts
Immunologic information also points to the need for a booster, said Anthony Fauci, MD, the chief medical advisor to the president and director of the National Institute of Allergy and Infectious Diseases.
“Antibody levels decline over time,” he said, “and higher antibody levels are associated with higher efficacy of the vaccine. Higher levels of antibody may be needed to protect against Delta.”
A booster increased antibody levels by ‘’at least tenfold and possibly more,” he said. And higher levels of antibody may be required to protect against Delta. Taken together, he said, the data support the use of a booster to increase the overall level of protection.