Washington DC - Covid vaccine booster shots hopefully will be strong enough that supplemental shots aren’t needed every six to 12 months, the top US infectious disease expert said on Sunday.

Booster shots were authorized by the Food and Drug Administration on Friday for every American 18 and older who has received a Pfizer-BioNTech or Moderna vaccine. Recipients of the Johnson & Johnson vaccine already had been cleared for boosters.

"We would hope, and this is something that we’re looking at very carefully, that that third shot... not only boosts you way up, but increases the durability so that you will not necessarily need it every six months or a year," Fauci said on ABC’s This Week. "We’re hoping it pushes it out more."

Prior to Friday’s announcement from the feds, a number of states had begun offering boosters for adults. The governors of Connecticut and New Mexico recently said they wouldn’t consider people fully vaccinated unless they had gotten boosters.

Fauci, the chief medical adviser to President Joe Biden, wasn’t willing to take it that far.

"Fully vaccinated right now by definition is the original two doses with… Pfizer and Moderna, and a single dose with J&J," he said.

More people in the U.S. have died of Covid-19 so far this year than in all of 2020, according to a Wall Street Journal report.

The country’s total number of Covid-19 fatalities from this year and last year surpassed 770,800 on Saturday, according to the Journal, which cited data from the federal government and Johns Hopkins University. There were 385,343 fatalities last year.

Fauci blamed the highly infectious Delta variant of the virus for the sobering numbers.

"We’re dealing with a Delta variant right now, which is very, very different from the original variants that we were dealing with before," he said. "This is a virus that is highly, highly transmissible."

"The more people that get infected, the more people that are going to get hospitalized. The more people that get hospitalized, the more people that are going to die," he said.

With the holiday season approaching, concerns about a possible surge in the virus are high, and Fauci cautioned Americans to get vaccinated, with boosters if possible, and play it safe.

"If you’re vaccinated, and hopefully you’ll be boosted too and your family is, you can enjoy a typical Thanksgiving meal, Thanksgiving holiday with your family," Fauci said. "There’s no reason not to do that."