Skip to main content

ALERT: KPBS 89.5FM is undergoing scheduled upgrade work which may result in a temporary signal outage. Click here to listen on our radio stream.

LATEST UPDATES: Tracking COVID-19 | Vaccines | Racial Justice

Expert Says COVID-19 Booster Shots May Be Recommended By Winter

A patient gets vaccinated against COVID-19 at Border View Family YMCA in Otay...

Photo by Matt Hoffman

Above: A patient gets vaccinated against COVID-19 at Border View Family YMCA in Otay Mesa, Calif. Feb. 24, 2021.

Just under two million San Diegans have been given their first dose of the COVID-19 vaccine, but it remains unclear if a third booster shot will be needed in the near future.

"The less the virus circulates, the less critical boosters are," said Shane Crotty, an infectious disease expert and professor at the La Jolla Institute for Immunology.

Listen to this story by Matt Hoffman

Crotty's research is known nationwide, and has been used by federal health officials during congressional hearings. When it comes to booster shots, Crotty said drug makers like Moderna have already been developing and testing them.

"And the booster shots did work and they also had a variant booster shot and that worked too," Crotty said.

RELATED: COVID-19 Vaccine Makers’ Booster Shots Aim At A Moving Target: Coronavirus Variants

So, booster shots will likely be available, the question is when or if they will be needed. Crotty said it comes down to two things: how long the immunity from vaccines lasts and the unknown with variants.

"Several of these variants of concern are more worrisome than the original strain and some of them escape immunity to some degree," Crotty said. "So, essentially the variants are tougher to stop than the original virus so the vaccine might not last as long against the variants. Trying to assess those two main situations is where we are."

Crotty estimates there is a 50-50 chance booster shots will be recommended by the winter of this year, but they might not be for everyone right away.

"It's entirely plausible that there will be an in-between kind of answer — that it may be that there's a risk assessment that says, 'OK, if you’re over 65 you should get a booster immunization at this point and if you’re under 65 you can wait longer,' maybe another year or something," Crotty said. "It doesn't have to be a one-size fits all solution."

He said the best case scenario is that the vaccines last a couple of years, but we do not know that yet.

"Basically, we just need more time," Crotty said. "We just don't have a clear historical reference point for saying, 'Oh, here’s how long immunity lasts after you've had an RNA vaccine.' We’re having to measure that and watch that every month as times goes by and try and extrapolate from now until when in the future do you need the booster."

RELATED: More Than Half Of Eligible San Diegans Receive First Dose Of COVID-19 Vaccine

Booster shots could also depend on local infection rates. Crotty added that for now, COVID-19 is likely to stick around in communities.

"SARS-CoV-2 is not going to be eradicated — it’s just it’s too widespread and too easily spread from person to person," he said.

Crotty says some areas will likely not get to herd immunity and continue to see pockets of outbreaks, but he said it is a key way to stop the virus, especially in internationally-traveled areas like San Diego.

"Herd immunity also isn’t just this line you suddenly cross like nothing happens before it, then everything happens after you cross it," Crotty said. "There’s a progression there and I think most people think we’re in a range where herd immunity should be having an effect now and it should get better and better the more people you can get vaccinated."

San Diego County is nearly three quarters of the way to having everyone ages 12 and over vaccinated. The state is set to fully reopen and lift nearly all COVID-19 restrictions on June 15.


San Diego News Now podcast branding

San Diego news; when you want it, where you want it. Get local stories on politics, education, health, environment, the border and more. New episodes are ready weekday mornings. Hosted by Anica Colbert and produced by KPBS, San Diego and the Imperial County's NPR and PBS station.

  • Need help keeping up with the news that matters most? Get the day's top news — ranging from local to international — straight to your inbox each weekday morning.

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

Photo of Matt Hoffman

Matt Hoffman
Health Reporter

opening quote marksclosing quote marksI am a general assignment reporter for KPBS. In addition to covering the latest news and issues that are relevant to the San Diego community, I like to dig deeper to find the voices and perspectives that other media often miss.

Want more KPBS news?
Find us on Twitter and Facebook, or sign up for our newsletters.

To view PDF documents, Download Acrobat Reader.