Many Americans who have received Pfizer vaccines are already preparing for a booster shot. Millions of people who have received the Moderna and Johnson vaccines wait eagerly to find out when their turn comes.

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 another week.

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 between experts and agencies. Documents released by FDA Tuesday indicate that this week’s decisions could be just as difficult.

The CDC advisory panel last month supported Pfizer boosters at six months for seniors, residents of nursing homes, and those with underlying health issues. However, Dr. Rochelle Walensky, Director of the CDC, ruled against her advisors and decided 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 limiting the public’s efforts to convince the unvaccinated to receive their first shots. They fear that talk of boosters could lead people to misunderstand the effectiveness of vaccines.

Experts will debate whether a third Moderna shot should only contain half of the original dose or if it’s best to give a single shot of J&J vaccine.

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.

Tim Anderson was a U.S. History teacher at a high-school outside Louisville, Kentucky. He had already received his Moderna shots several months before he contracted COVID-19. Although his symptoms were “like a sledgehammer”, he believes that the vaccine saved him and his girlfriend from more serious complications of the disease.

They are currently awaiting the Moderna booster shot.

Anderson, 58, stated that until we have enough immunity in our own bodies and as a whole, we will not be able to do what is necessary.

These FDA meetings are occurring as U.S. vaccines rise to above 1 million per hour on average. This is an increase of over 50% in the past two weeks. This rise is primarily due to Pfizer boosters, and employer mandates for vaccines.

Although the FDA and CDC have so far approved Pfizer boosters only for certain groups, Biden administration officials, Dr. Anthony Fauci included, suggested that additional shots would eventually be recommended to most Americans.

The FDA didn’t indicate Tuesday that it was aiming to clear the booster in a review of Moderna data. It stated that vaccines made in the U.S. provide protection and raised concerns about some Moderna’s data.

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 submitted data to FDA regarding different options for J&J vaccine recipients. One was a booster shot at 2 months, and the other at 6 months. In its FDA submission, the company stated that a six-month booster was recommended. However, in certain situations, a second dose may be administered at two months.

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 not yet released patient data for a six-month booster vaccine, early tests of virus-fighting antibodies indicate 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.