What we know about Covid-19 vaccine booster shots

(ABC 6 News) – As the Delta variant spreads, we are learning Covid vaccines become less effective over time. Health experts say the answer is an additional dose of vaccine, often called a booster shot.

A new study released Wednesday showed, if administered six months after the original dose, Johnson and Johnson’s booster shot leads to an immune response that is nine times greater than an immune response without a booster.

There is a lot we do not yet know about Covid vaccine booster shots. The data is limited, and it’s too soon to make recommendations for entire populations, but we do know a lot about booster shots in general.

"Over time — and it does take a long time– six to eight months or more, immunity people achieve from the Covid vaccine does start to wane," Dr. Melanie Swift with Mayo Clinic’s COVID-19 Vaccine Allocation and Distribution Group said.

Like most vaccines, the Covid vaccine is only effective for so long. This is the same reason we get a new flu shot every year.

MercyOne’s chief medical officer, Dr. Paul Manternach, said there are too many moving pieces right now for experts to start suggesting everyone get booster shots for Covid.

"There are three vaccines with different characteristics and every individual has their own unique immune response. I think that will determine if every individual will need a booster shot," Dr. Manternach said.

While we do know booster shots increase immunity, health experts say not everyone should be rushing to get their booster shot.

"While we have an adequate vaccine supply to meet this current booster recommendation, we don’t have a limitless supply of vaccine," Dr. Swift said.

Mayo Clinic recommends immunocompromised people get their boosters much sooner than six to eight months.

"So really we want to get your immune system reminded and moving a little bit faster," Dr. Manternach said.

Mayo Clinic experts say we can expect booster shots to roll out in late September.

For the Johnson and Johnson vaccine, that would mean getting a second shot. For Moderna and Pfizer, the booster will be the third shot.