By Mike Hellgren

BALTIMORE (WJZ) — The FDA is expected to give the green light this week to booster shots for those already vaccinated with Moderna and Johnson and Johnson—a huge step in protecting against breakthrough infections and waning immunity.

The agency is also expected to allow the mixing and matching of different vaccines.

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Dr. Kathy Neuzil is with the University of Maryland School of Medicine, which assisted with a study that showed J&J recipients given a J&J booster dose increased their antibodies by 4 times. Those given a Moderna booster saw their antibodies increase by 76 times after 15 days.

“Don’t panic. We are seeing some evidence of waning effectiveness of these vaccines, but it’s waning relatively slowly and the protection against hospitalization and death is holding strong,” Dr. Neuzil told WJZ Investigator Mike Hellgren. “The good news is these vaccines were quite well tolerated—whether you give the same type of booster or a different type of booster. We saw local reactions, some arm pain, what you would expect to see but no red flags from the safety standpoint for mixing and matching.”

Some want to receive boosters because of concerns about breakthrough infections among the fully vaccinated. Such breakthrough infections have made up almost 13 percent of cases in Maryland since January.

Former Secretary of State Colin Powell died this week in Maryland of Covid-19 complications. He was fully vaccinated but suffered from a rare blood cancer that increased his risk of severe illness.

“It’s not that the vaccine didn’t work. His immune system didn’t work to be able to make him a potent enough immune response to protect him,” said CBS News Medical Contributor Dr. David Agus.

Seventy-year-old Bernard Brown is fully vaccinated and told Hellgren he plans to get the additional dose. “Covid-19 is killing people minute by minute. If there’s a possibility of some type of extra vaccine that’s going to keep me alive, I’m all for it.”

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The FDA is expected to recommend Moderna and J&J boosters for people 65 and older and those 18 and older with certain jobs or medical conditions that put them at high risk.

Local health officials say they are prepared to give out more boosters once the federal government gives the approval. “We’ll be ready to provide those as will others. We have the supplies on hand,” said Anne Arundel County’s Health Officer Dr. Nilesh Kalyanaraman.

Many people in Maryland who have received Pfizer are already eligible for a Pfizer booster. You can read the current guidance here.

Dr. Neuzil said the priority is still convincing the unvaccinated to get the shot.

“We can’t forget about the unvaccinated. We need the unvaccinated to get their primary series of vaccines or this virus is going to be able to keep circulating,” she said.

This comes as some local governments are trying to get employees to comply with vaccine mandates.

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Baltimore City’s mandate went into effect Monday. As of Tuesday morning, 53 percent of employees had uploaded their proof of vaccination.