In-Depth: When we'll need a COVID-19 booster shot

Posted at 4:51 PM, Jun 18, 2021
and last updated 2021-06-22 01:45:12-04

SAN DIEGO (KGTV) -- There’s a growing consensus that Americans will eventually need a COVID-19 booster shot. The question is, when?

In recent weeks, the CEOs of Pfizer and Moderna said they believe boosters will be needed within a year of immunization, potentially as early as September for those who were first in line for their initial doses.

Dr. Anthony Fauci, the nation’s top infectious disease physician and the chief medical adviser to the president, said it’s still too soon to forecast a timeline.

“The determination is not made by drug companies. The determination is made by the public health need,” he said at a briefing Thursday.

“That could be a year. That could be 18 months. That could be much longer. We're going to have to follow it,” he added.

San Diego researchers studying the durability of the COVID vaccines say boosters are not yet a foregone conclusion.

“Will booster shots be required? I put it at a 50-50 chance currently,” said Dr. Shane Crotty of the La Jolla Institute for Immunology.

There are two factors that will determine if boosters are needed: whether variants can escape our protection, and how long the vaccines last inside the body.

So far, the data on variants looks great, Dr. Crotty said.

“If you’ve got two immunizations with the mRNA vaccines, you’re very highly protected against any of these variants,” he said.

How long the vaccines keep will working inside the body is difficult to project because there haven’t been licensed mRNA vaccines before, he said.

Research by led by Crotty and LJI’s Dr. Alessandro Sette shows that in about 90 percent of people, protective immune cells remain strong for at least six to eight months. They’ll release another update on the one-year mark soon, but other research suggests protection remains strong.

Studies on other coronaviruses suggest immunity does gradually fade, allowing people to be reinfected. Not “within a few months or even within a year or two,” said epidemiologist Dr. Emily Martin of the University of Michigan, “But over years, you do get coronaviruses over and over again and so that to me suggests that eventually, we may need to think about updating the vaccine.”

Even though the science on boosters is still working itself out, preparations by vaccine-makers are well underway. This week, Moderna announced it will sell another 200 million doses to the U.S. government that could be used as boosters or initial shots for young children who don’t currently qualify for vaccination.

More than half of the doses will begin arriving between October and December, with the remainder in the first quarter of 2022. This latest agreement brings Moderna’s overall commitment in the U.S. to 500 million doses.

Pfizer’s CEO predicted people may need a booster just 8 to 12 months after their second dose. That means the first group of healthcare workers immunized last December might need a booster in September.

In an interview this week with ABC 10News, San Diego Board of Supervisors Chair Nathan Fletcher said he thought boosters are likely this fall.

“But when you get that booster, it will be much more similar to how you go get a flu shot,” he said.

If and when boosters arrive, the county does not plan to run mass vaccination “superstations,” he said. Instead, private healthcare providers will largely distribute the shots.

The county might offer boosters at smaller vaccine “pods,” similar to the way it distributes flu vaccines, he said.