To boost or not to boost? That is the big question surrounding COVID-19 vaccines. Based on recent data from the Centers for Disease Control and Prevention (CDC), the COVID shot’s effectiveness against infection has decreased over time. This information is behind the government’s push to offer a third, or booster dose, this fall to enhance immunity to those who have already been fully vaccinated.

According to Axios, one of the reasons efficacy fell is because the first two doses were given in three-or four-week intervals which didn’t allow the vaccines enough time to build immunity.

“When you make that decision to do a three- or four-week interval, it sacrifices length of protection and durability of protection,” explains Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine and a noted virologist. Hotez says that the initial interval was critical to saving lives but meant that a booster shot would likely be required.

Experts say that an eight-month gap between the second and third dose would offer significant protection, says Axios.

“That may be it for a while, we may not need annual boosters,” Hotez said. “This could be the third and done.”

His opinion was echoed by CDC director Dr. Rochelle Walensky who suggested that a third shot may sufficiently strengthen the long-term protection of the Pfizer and Moderna mRNA vaccines. Her sentiments came a day after U.S. health officials announced they are planning to offer the booster shot eight months after people have received their second COVID-19 vaccine, according to CNBC.

“The virus has been humbling, so I don’t want to say never, but we are not necessarily anticipating that you will need this annually,” Walensky said. Authorization for the booster must come from the Food and Drug Administration and the recommendation of the CDC vaccine advisory panel.

Dr. Scott Gottlieb, the former FDA chief, said that boosters can help head off the winter surge of COVID-19.

“The first two doses were administered so close together, they really qualify as a primer,” he said, in an interview on CNBC’s “Squawk Box.” “And this is the booster that’s hopefully going to induce a longer-term immunity, a more durable immunity.

For people who got the single dose Johnson & Johnson jab, the latest word from U.S. Surgeon General Vivek Murthy is that boosters “will likely be needed.” Data is still being gathered about the J & J vaccine’s efficacy partly because it was rolled out in March, months after the Pfizer and Moderna shots.

But many scientists and healthcare experts are up in arms about the proposed booster shot. They are confused and concerned over the Biden administration’s recommendation to promote booster shots prematurely, in their opinion. According to STAT, Anna Durbin, a vaccine expert at Johns Hopkins University, says the vaccines continue to be highly effective in doing what they were designed to do: prevent severe illness, hospitalization, and death.

She says that the decision to boost the vaccine right now isn’t based on science.

“I think there’s this tidal wave building that’s based on anxiety,” she told STAT. “And I don’t think it’s based on scientific evidence that a booster is needed.”

Dr. Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia and an adviser to the National Institutes of Health and the Food and Drug Administration, thinks boosters may eventually be needed, but adds that almost all evidence shows that protection against severe disease is still strong and could last for years.

“So, the notion that we are trying to get ahead of it by boosting after eight months is premature,” he said, according to STAT.