Nearly every vaccinated Michigan adult will likely be able to get a booster as soon as this week after a decision Wednesday by the U.S. Food and Drug Administration cleared the use of boosters for Moderna and Johnson & Johnson COVID vaccines.

The FDA also authorized medical providers to mix-and-match vaccines, allowing vaccinated people to receive a different vaccine as a booster than what they originally received — a clear sign the FDA has faith in the early science that suggests that doing so is safe and can even provide better immunity against the coronavirus.

The debate now shifts to the Centers for Disease Control and Prevention’s advisory committee, which is expected to take up the recommendations Thursday. If, as expected, the CDC signs off on the plans, boosters for all three U.S.-approved vaccines should be broadly available by the end of the week.

Boosters for the Pfizer vaccine were approved in September for adults 65 and older and people in high-risk groups.

The FDA Wednesday greatly expanded the ability for more boosters, announcing:

• Moderna boosters may be given at least six months after the initial two-dose series to anyone 65 and older as well as adults at high risk of severe COVID-19 or with “frequent institutional or occupational exposure to SARS-CoV-2.”
• The J & J booster may be given to people aged 18 and older at least two months after their initial vaccines.
• Each of the three vaccines — Pfizer, Moderna and J & J — may be offered as a heterologous vaccine, meaning that boosters don’t have to match the manufacturer of the first shots.

The ability to mix vaccines is good news for several reasons, said Dr. Juan Marquez, medical director at Washtenaw County Health Department.

Until now, CDC guidelines generally forced individuals getting second doses, third doses (for immunocompromised people), or boosters, to receive vaccines from the same manufacturer. In rare instances, individuals in the early days of the vaccine rollout may have had two different vaccines.

But new and growing research suggests that a mix-and-match approach to the COVID vaccine works better, essentially teaching the body to respond to different stimuli to mounting a defense against an invading coronavirus.

“With a different route of exposure for the same virus, you essentially may alert other parts of your immune system,” he said.

A study released last week suggested that people who originally received the single-dose J & J vaccine and then took a Moderna booster saw a 76-fold increase in protective antibodies, compared to just a four-fold increase for those who received both initial and booster doses of J & J.

The results from the study, involving 458 people, are preliminary and must be peer reviewed.

The ability to change up which manufacturer’s vaccine is taken is likely to also mean less waste for health departments and other providers, Marquez said.

When vaccines were in short supply earlier this year, the focus was on zero-waste of the sought-after vaccines as the state worked toward a 70 percent vaccine rate. Some providers handed out doses at the end of the day to passersby to avoid having to throw out unused doses.

Now, vaccine shortages have largely disappeared. Those eager to get them have generally received them, as a sizable minority of residents continues to balk. Just 60 percent of the state’s residents 16 and older — 4.8 million — have been fully vaccinated, mostly with Moderna and Pfizer vaccines, according to state data.

“If someone comes in at the end of the day, we’ll crack open a new vial if we have to,” Marquez said. “Everyone involved with the effort cringes when we have to waste doses, but it’s critical to have as many folks vaccinated as possible. It’s a trade-off.”

With the ability to offer a booster dose from a different manufacturer, that end-of-the-day vaccine recipient may be able to get a dose from an opened vaccine dial, even if its manufacturer doesn’t match that of their first doses, he said.

“And we can be confident in saying, ‘Yes, this is just as efficacious,” he said.

Eligibility? An honor system

While the three boosters have restrictions on who is eligible to receive them, there is mounting evidence that Michigan providers are not asking a lot of questions of costumes seeking them.

For example, the Pfizer boosters are supposed to be limited to people 65-and-older and those who were immunocompromised or at higher health risks. They have been given out based on the honor system.

But with abundant supplies available across the state, several health departments told Bridge Michigan this week they aren’t asking for proof of a person’s high risk or turning anyone away if they seek a booster.

“We’re following guidelines, but we do take folks at their word,” said Nick Derusha, health officer for the LMAS Health Department in the eastern Upper Peninsula and president of the Michigan Association for Local Public Health, which represents the state’s 45 local health departments.

When vaccines were more scarce, said Washtenaw County’s Marquez, staff tried to do “a little more vetting, but operationally, really it’s impossible.”

Nearly 348,000 additional or booster doses had been given out as of Wednesday, according to state data.

Next up: Vaccines for little ones

Federal panels are next scheduled to take up the question of whether to approve COVID vaccines for 5 to 11-year-olds.

The same FDA panel that last week made recommendations about boosters is set to take up Pfizer’s request to authorize vaccines for children 5 to 11 years old at its meeting Oct. 26. The CDC’s Advisory Committee of Immunization Practices, which determines who will be eligible for vaccines and when, is scheduled to meet Nov. 2.