This week, federal regulators will begin to address this question.
The Food and Drug Administration will convene its independent advisors on Thursday and Friday to begin the process of deciding if additional doses of the vaccines should be given and, if yes, when and who. The final approval is not expected until at least one week later.
The FDA advisors will then make their recommendation and the agency will decide whether or not to authorize boosters. Next week, the Centers for Disease Control and Prevention convenes a panel to discuss who should receive them. The CDC director must approve the panel's decision.
This is a process to increase public trust in vaccines. However, it has already caused conflicts and disagreements between experts and agencies.
The CDC advisory panel supported Pfizer boosters last month at the six-month mark for seniors, residents of nursing homes, and those with underlying health issues. However, Dr. Rochelle Walensky , Director of the CDC, ruled that boosters should be available to people with high-risk jobs like teachers and health care workers. This added tens to millions to the already impressive list.
Some experts in health fear that the back-and forth deliberations could be affecting the public effort to persuade those who aren't vaccinated to get their shots. They fear that people will wrongly doubt vaccine effectiveness by talking about boosters.
The FDA panel is meeting to discuss the Moderna and J&J vaccinations. This time, the FDA panel will likely make more complex decisions. Experts are discussing whether a third Moderna shot should only contain half of the original dose or when the best time to give a second shot.
The panel will also examine the safety and effectiveness when different vaccine brands are mixed-and-matched. This is something that regulators have yet to endorse.
According to the CDC, an estimated 103 million Americans have been fully vaccinated using Pfizer's formula. 69 million are with Moderna's vaccine and 15 million with J&J. Because Pfizer submitted its data before other vaccine manufacturers, regulators took the Pfizer boosters question first.
Each of the two Moderna shots contains 100 micrograms each. The drugmaker claims that 50 micrograms should be sufficient to give a boost for healthy individuals.
According to a company study, 344 people received a 50-microgram shot six month after their second dose. Their levels of virus-fighting antibody increased by a whopping 12%. Moderna claimed that the booster caused a 42-fold increase in the amount of antibodies capable of targeting the extra-contagious Delta variant.
According to Moderna, side effects are similar to those that Moderna recipients experience after receiving their second regular shot.
The company provided data to FDA regarding the J&J vaccine. It offered two options for booster shots at two and six months. The company didn't indicate its preference.
J&J published data in September that showed that a booster administered at two months gave 94% protection against mild-to-severe COVID-19 infections. Although the company has yet to release patient data for a 6-month booster, early tests of virus-fighting antibodies suggest that it offers even greater protection.
J&J claims that the vaccine is still about 80% effective in preventing COVID-19 hospitalizations in America, even without a booster.
Scientists insist that all three vaccines in the U.S. offer strong protection against severe diseases and death from COVID-19. It is unclear how fast and how often protection against milder infections may decrease.
Researchers compared 14,000 people who received their Moderna vaccine one year ago to 11,000 who were vaccinated just eight months ago in a recent study. The rate of "breakthrough" infection in the newly vaccinated group was 36% lower than those who were vaccinated earlier.
Medical experts are still debating the science behind giving additional shots to people who have substantial protection.
In August , the White House and its top medical advisors announced broad plans to offer boosters for nearly all adults. They cited signs of declining protection and the rise in delta variant. Experts argued that there was no data to show that such widespread use would prevent breakthrough infections or alter the overall trend of cases.
Although the FDA and CDC eventually reduced Pfizer booster use, Biden administration officials, Dr. Anthony Fauci included, suggested that additional shots would be recommended for most Americans.
They point out data from Israel that shows lower rates of severe disease and infections among those who have received a third Pfizer shot.
These FDA meetings are occurring as U.S. vaccinations rise to above 1 million per hour on average, an increase more than half of the past two weeks. This rise is largely due to Pfizer boosters and employer vaccine mandates .