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This colorized image, taken from a scanning electron microscope, shows a cell (teal) infected with virus particles (orange) from the B.1.1.7 variant of the SARS-CoV-2 virus. The image was captured at the National Institute of Allergy and Infectious Diseases' Integrated Research Facility in Fort Detrick, Maryland. (Provided by NIAID)

Coronavirus vaccine booster shots are coming. But are they actually going to do any good?

The answer is a complicated mishmash of yes/no/maybe. Yes, they will likely give a little jolt to your immune system to better protect you in case you’re infected with the fast-spreading delta variant. No, they likely won’t do much to help us as a state reach herd immunity. Maybe they will make things better. Maybe they will make things a lot more complicated.

Here’s what you need to know.

Have booster shots been approved?


The federal Food and Drug Administration has authorized an additional dose of vaccine for people with certain health conditions that lead to a suppressed immune system. People who are eligible include:

  • Those who are receiving active treatment for tumors or cancers of the blood
  • Those who have received an organ transplant and are taking medicine to suppress their immune systems
  • Those who received a stem cell transplant in the past two years and are taking medicine to suppress their immune systems
  • Those who have moderate or severe primary immunodeficiency from conditions like DiGeorge syndrome or Wiskott-Aldrich syndrome
  • Those with an advanced or untreated HIV infection
  • Those receiving active treatment with high doses of corticosteroids or other medications that suppress the immune system

Boosters are authorized only for people who received the Pfizer or the Moderna coronavirus vaccine.

If you’re eligible for a booster, how do you get one?

You just sign up for a shot somewhere.

There’s no separate queue for people seeking booster shots. Any hospital, drug store, grocery store, doctor’s office, mobile clinic or pharmacy/soda fountain that is offering shots will do. You’re even eligible for a gift card.

The official recommendation is that you get the same brand of vaccine you got for your first two shots. But mixing and matching is allowed if, say, you’re in the Pfizer Gang, but there’s only Moderna available.

You don’t need a doctor’s note. The state Department of Public Health and Environment says people can “self-report” their immunosuppressed status and has ordered vaccine providers to give out booster shots based on peoples’ word.

Can I lie?

*Looks around nervously.* No, of course not!

OK, that’s already happening. Even Gov. Jared Polis sort of winkingly suggested at a news conference that people could take matters into their own hands and go get a booster under false pretenses. Then he stopped winking and explicitly told Axios Denver that he definitely meant to say that people can sneak a booster before it’s officially allowed.

Vaccine providers have the ability to check your record in the state immunization registry before they dispense your dose. They could deny you a shot if they see you’ve already had two and haven’t said you’re in the group authorized for a third. But it’s not like the booster police are going around checking cards.

A box containing the Johnson & Johnson/Janssen COVID-19 vaccine at the Lincoln County Fairgrounds in Hugo, Colorado, on March 19, 2021. The public health department administered 298 doses of the single-shot vaccine and had an additional 20 to give out at a future event. (Brian Malone, Special to The Colorado Sun)

What if I got the Johnson & Johnson vaccine?

No booster for you.

At least not yet. It’s a bit confusing. The FDA hasn’t authorized boosters for people who received the J&J vaccine. There’s not a lot of studies that address the effects. But other countries are allowing a booster dose of the Pfizer or Moderna vaccine for people who received a vaccine similar to J&J’s, the AstraZeneca vaccine.

So it’s unclear when U.S. authorities might make a decision on J&J boosters. In the meantime, people are again taking matters into their own hands.

Will the boosters work?

Yes. Probably. Hopefully.

The reason people with immunosuppression are first up for boosters is that their first two doses of vaccine might not have done very much for them. By definition, their immune systems are dialed down, so they were less likely to have developed good defenses after the first two doses.

In one small study of kidney transplant recipients, only about 10% of participants developed antibodies after two doses of vaccine. Other studies are a little more promising — including one that found a response rate of around 50% after two doses. But that’s still a lot of immunosuppressed people who got vaccinated and have no protection.

Dr. Lisa Miller, a professor of epidemiology at the Colorado School of Public Health, said booster shots can hopefully provide some protection for people who didn’t respond after their first two doses and bolster the protection for others.

“For those people, based on what data are available, it looks like a third dose isn’t harmful and it helps a sizable proportion of those people have a larger antibody response,” she said. “So that recommendation is pretty clear.”

What about for people without immunosuppression?

It will likely help a little.

There’s growing evidence that the immune response from the vaccines wanes over time in everyone. That’s especially concerning for older people who are most at risk for a severe coronavirus infection.

Miller wants to be clear: The vaccines all provide good protection against severe illness, hospitalization and death, even after a few months. But she said a booster might rev things up again, like downing an espresso at 3 p.m. to combat the afternoon droopies.

The federal government is expected to tell everybody who received the Pfizer or Moderna vaccines to go get a booster shot eight months after they received their last dose. Those shots could start sometime in September.

Is this a new vaccine formula?


It’s another dose of the same stuff as before. It’s not been reformulated to target specific coronavirus variants.

If it’s just another shot of the same vaccine, how does it protect against the delta variant?

Because delta’s superpower is how fast it moves. So your immune system might need the espresso-jolt of a booster shot to catch up.

Gregg Dean is a professor of microbiology and immunology at Colorado State University. (He’s also developing two coronavirus vaccines.)

Dean said early studies suggest that, once it’s weaseled its way inside you, the delta variant starts replicating days sooner than the original forms of the coronavirus. That means the variant can end up cranking out 1,000 times more virus than earlier forms, making people sicker more quickly and spewing more potentially infection-causing virus particles out into the world.

Gregg Dean, department head and professor of Microbiology Immunology and Pathology at Colorado State University, is working to develop a vaccine for the COVID-19 virus. Photographed March 31, 2020. (Provided by Colorado State University)

“When you think about it, that virus has a head start,” Dean said. “And we are in a race, as humans, against a virus like COVID-19. The virus is racing to replicate inside us. And our body is racing to develop an immune response.”

Your immune system has multiple ways to respond to an infection — there are antibodies and T cells and memory B cells. And it has a long memory, so even if your vaccine’s effectiveness wanes, it’s not like your immune system has forgotten what the coronavirus looks like.

But over time, Dean said, the number of antibodies circulating in your body following your vaccination will decline, meaning your immune system can’t respond as rapidly. And, against a fast foe like delta, that’s trouble.

So, a booster shot might be able to put more antibodies on patrol. Basically, it’s the difference between having firefighters hanging out at the station waiting for a call that your house is on fire and having firefighters suited up and waiting down the block in an idling firetruck.

“If we have antibodies there right when we’re exposed to the virus and those antibodies can coat that virus, that’s our earliest chance to prevent infection,” Dean said.

Will this help slow the spread of the delta variant?

Ehh, not very much.

Epidemiology math is tough and sometimes counterintuitive. Basically, with the delta variant being so transmissible, the incremental boost of vaccine effectiveness in already-immunized people isn’t going to be enough to move the needle significantly on a population-wide level.

One of the biggest advocates for this argument is a Boston University professor named Eleanor Murray. It’s possible Murray is the most famous epidemiologist in America; her @EpiEllie Twitter account has more than 85,000 followers. (For comparison, Dr. Anthony Fauci, the nation’s virus-fighter for all seasons, isn’t on Twitter, but the agency he leads, the National Institute of Allergy and Infectious Diseases, has 69,000 followers.)

In a tweet thread and, subsequently, in news commentaries, Murray laid out a case that booster shots will not save us as a society from delta-driven spikes in infections. It’s a lot of calculations involving measurements of a virus’ ability to spread and the impact vaccines and boosters would have on that. Fans of equations involving R0 (pronounced, for the uninitiated, “Arr-naught” like a pirate engaged in a name-calling contest) should click those links.

The upshot is this: The number of people who are vaccinated in America is too small, the increase in vaccine effectiveness is likely to be too insignificant and the delta variant is just too transmissible. Even more surprising: Considering the current vaccination rates in the country and jolting vaccine effectiveness through booster shots, the delta variant would still likely be able to spread faster than the original coronavirus did when it first arrived.

Miller, the CU epidemiologist, said Murray’s calculations check out, but she disagrees with Murray’s analysis. Even if they might not do much on a population-wide scale, boosters can still have benefit in better protecting individuals.

“It’s not the silver bullet, but it’s one of many things we can do,” Miller said. “It’s one more tool we can add to the toolbox. We need layered protections.”

What will slow down delta?

Vaccinate, vaccinate, vaccinate.

This is Murray’s counter-argument to booster shots. Mathematically, the best way to slow down delta isn’t to improve the protection of people who are already vaccinated. It’s to extend immune protection to more people who currently have none.

Miller believes it’s possible to do both — to make inroads with the unvaccinated while boosting the vaccinated.

“We certainly aren’t going to try to stop trying to get everyone vaccinated,” she said.

Critics of boosters, though, worry that will be hard to do. 

But there’s a lot of vaccine available. What’s the argument for not boosting?

There’s two reasons often given.

The first is that launching a booster campaign might undermine the regular vaccination campaign. Colorado’s efforts to reach unvaccinated people have become highly individualized — they’re about making sure you have clinics operating in places and at times that make it easy for people to decide to get a shot. Providers have been told never to miss an opportunity to vaccinate someone, even if that means letting doses leftover in a punctured vial go to waste.

But there are more than 3.2 million people in the state who are fully immunized — many of whom will likely be seeking booster shots in the coming months. So the state will again have to figure out how to balance demand for vaccines.

For what it’s worth, Polis showed no concern when asked about that this week.

“We can walk and chew gum at the same time,” he said.

The other reason is more global.

Looking worldwide, there actually isn’t that much vaccine available. In many of the world’s poorest countries, less than 5% of the population is vaccinated. In Africa, only about 2% of the continent’s population is vaccinated.

That’s why the World Health Organization has condemned plans by wealthy nations for booster shots — essentially tying up vaccine in places that are already much better protected. “They make a mockery of vaccine equity,” one WHO official said on Thursday.

But this isn’t just a humanitarian argument. Health officials concerned about global vaccine disparities fear it could boomerang back to also hurt the countries looking to run booster campaigns.

Why? Because if infection rates explode in vaccine-deprived nations, that could lead to new variants of the virus emerging. New variants that might be even worse than delta.  

Don’t say that!


This all really sucks.


Yes it does.

John Ingold is a co-founder of The Colorado Sun and a reporter currently specializing in health care coverage. Born and raised in Colorado Springs, John spent 18 years working at The Denver Post. Prior to that, he held internships at...