CLEVELAND (WJW) — The CEO of drug company Moderna announced this week that they will make a third booster shot for the two-dose vaccine available by the fall.

Studies show their vaccine is more than 90-percent effective against COVID six months after the second shot, but it’s still unclear how long immunity will last.

“MRNA vaccines are incredibly flexible and it’s very easy to change them,” said Cleveland University Hospitals infectious disease specialist Dr. Amy Edwards. 

She says she appreciates the fact Moderna is looking ahead to have a booster ready. “But I hope very much that in making the booster they’re not inhibiting their ability to make the primary vaccine which I think at this point needs to be their primary focus.”

Pfizer’s CEO, whose vaccine is just as effective, announced Thursday people will likely need a booster of their shot within a year.

Edwards believes boosters will become necessary but says the timeline is hard to say for certain. 

“There’s no data to support that at the current moment,” she said. “The study is only six months old and at six months there was still 90 percent efficacy.”

Ohio’s Summit County Health Commissioner Donna Skoda says they have been ready to eventually administer a booster since day one.

“What we have prepared is many of the strategies that we use now, vaccine trailers, mobile units, larger drive-thrus, we would just then use that for the booster.”

She says that could help public health pull double duty against the flu. “Then we could do the booster and the flu shot, you know, and try to get folks at a higher vaccination level.”

Edwards says the vaccine efficacy is high enough to eliminate COVID in the United States. “But given the amount of vaccine hesitancy that’s out there I think a lot of us anticipate that we probably won’t see eradication, so there will be these flares.”

Both in medicine and public health, there are a lot of questions that still remain unanswered. “Viruses mutate a lot and that’s how they survive. And so it’s hard to make the perfect vaccine right out of the gate.”