Coronavirus boosters for fully vaccinated are coming soon for everyone. Why?

The answer is data from here and abroad.
Aug. 23, 2021
A man in a convertible gets his vaccine at a drive-thru mass vaccination at Coors Field.
Scientists have been racing to keep up with the coronavirus, particularly since the emergence of the delta variant. They now have enough data to see that booster shots can help protect those already fully vaccinated from COVID-19, but the story is complicated. Photo: Cyrus McCrimmon, for UCHealth.

COVID-19 vaccine booster shots for everyone are coming soon.

At the same time, the latest research – including a study co-authored by UCHealth emergency medicine specialist Dr. Adit Ginde – is showing the vaccines to be excellent at protecting people from getting severe infections that require hospitalization.

This may look like a contradiction. It’s just science.

Federal health officials on Aug. 18 announced plans to offer booster shots to fully vaccinated people starting in September. UCHealth patients who are 70 and older and health care workers may now schedule appointments for booster shots if they finished their initial vaccination series at least six months ago.

Those who received both doses of Pfizer or Moderna mRNA vaccines will be eligible. (Johnson & Johnson and AstraZeneca vaccine recipients can expect the same, but those vaccinations started later and vaccine experts still are reviewing data.)

Vaccine appointments at UCHealth can be made by going to My Health Connection and clicking on Schedule Appointment, or by using he UCHealth mobile app.

Concensus developing on booster shots

Uncertainty has been a constant throughout the pandemic. We wore (or didn’t wear) masks to protect others before we learned that they protect us, too. We thought hydroxychloroquine might help coronavirus patients until we learned it didn’t. We thought COVID-19 came and went until “Long COVID” bared its teeth. We thought vaccines would take years to develop and they took months. All this – and, now, the rapidly slowly crystallizing consensus regarding who needs coronavirus vaccine boosters and when – comes down to the simple fact that, even when running at its fastest clip, solid science can’t keep up with a recurring wildfire of a global pandemic.

Studies must be conceived, designed, approved, and funded; data must be collected, vetted, and analyzed; reports must be written, peer-reviewed, and accepted for publication. Considering all that, the publication of a study involving more than 3,000 patients in 21 hospitals in 18 states just a month after collecting its last data might be considered a true feat.

Tough race

Ginde, who is also vice chair for research in the department of emergency medicine at the University of Colorado School of Medicine, is a key member of the IVY Network team that delivered those results to the CDC and continues to track coronavirus hospitalizations and deaths. Its goal is to deliver hard data on real-world vaccine effectiveness to policymakers and the public. Ginde and his CU Anschutz team enrolled more than 500 of the study’s patients – the most of any participating institution – at UCHealth University of Colorado Hospital on the Anschutz Medical Campus. He says many months would normally pass before such a study’s results came to light. But even this frenetic pace – the group has managed to report on its ongoing work roughly once a month – they can’t catch the coronavirus.

Photo of Dr. Andit Ginde
Dr. Adit Ginde

“The data we published through July already seems old now,” Ginde said.

The world’s least-favorite Greek letter – delta, as in the now-dominant SARS-CoV-2 variant – is to blame. When Ginde and colleagues’ latest study window closed on July 14, delta comprised 7.3% of the cases among the 400 positives that the team had sent for whole-genome sequencing starting in late March. As of August 14, the CDC estimated that delta made up 86.1% of new cases nationally.

Even with delta, the numbers continue to support the view that the coronavirus is now a “pandemic of the unvaccinated.”

“The overwhelming majority of hospitalizations and deaths continue to occur among the unvaccinated,” U.S. Surgeon General Vivek Murthy said in the Aug. 18 press briefing announcing the booster policy.

But delta is six to seven times easier to catch than the original coronavirus, perhaps because it multiplies some 1,000 times more aggressively in the nose and throat early in the course of infection (and is thus easily expelled into the air).

In the briefing, CDC Director Dr. Rochelle Walensky cited a preprint study showing the Pfizer vaccine’s effectiveness against mild COVID-19 infection to plunge from 76% with the alpha (British) variant that was dominant in the late spring and summer to just 42% now, with Moderna’s dropping from 86% to 76% with delta. She also noted a new CDC-published study that found vaccinated patients in New York were protected 92% of the time when alpha was dominant and 80% by late July – and delta was still ramping up at that point. Then Walensky pointed to a study showing vaccine effectiveness in nursing homes to have fallen from 75% pre-delta to 53% with delta. She then brought up the IVY Network’s hospitalization study, focused on prevention of severe disease, and its conclusion that vaccines appeared protective against severe disease for at least six months.

Mounting evidence

But that was before delta, and pandemic policy is now all about delta. To underscore that point, Walensky cited CDC data from Aug. 6 showing 92% vaccine protection against symptomatic infection among health care workers, first responders and others prior to delta falling to just 64% with delta.

Studies from Israel and emerging U.S. data point to increasing numbers of breakthrough infections among the vaccinated – and, in Israel, hospitalizations, particularly among the aged who got shots soon after they became available to the general public in December 2020. Such infections among the fully vaccinated look to be caused by a combination of delta’s extreme transmissibility and vaccines’ waning effectiveness over time. Ginde anticipates that, within the next month or so, his group’s ongoing study will likely show decreasing vaccine effectiveness in prevention of severe COVID-19 and hospitalizations.

“We won’t know the results until we complete the data collection and analysis, but anecdotally, I think we’ll see some waning vaccine effectiveness. Likely it’ll still be quite high for the prevention of hospitalizations,” Ginde said.

Ginde says he suspects that encouraging but yet-unpublished data on the immune response to booster shots that Moderna and Pfizer have submitted to the FDA, along with the emerging epidemiological data, are probably informing the federal decision to move forward with booster shots for the general public.

“I fully support and anticipate that we are going to need booster shots this fall,” Ginde said. “We need a little bit more data to prove that boosters are needed to prevent hospitalization, but I think there’s already sufficient evidence to see that boosters can prevent symptomatic infection.”

Waning antibodies

In the press briefing, Dr. Anthony Fauci, President Biden’s chief medical adviser, cited new research concluding that higher antibody levels translate into greater vaccine protection, that mRNA-vaccine antibody levels fall over time, that it takes about two-and-a-half times more antibodies to neutralize delta than the original coronavirus variant, and that a Pfizer or Moderna vaccine booster shoots up antibody levels by a factor of 10 or much more.

“All of this supports the use of a third booster mRNA immunization to increase the overall level of protection,” Fauci said.

If the influence of Ginde and colleagues’ work related to vaccine effectiveness among the immunocompromised is any measure, the IVY Network’s results will carry weight in Washington.

In an earlier phase of its ongoing study, the team found full vaccination with Moderna or Pfizer to be about 91% protective against hospitalization with COVID-19 among adults, but just 63% effective among the immunocompromised – and that was before delta grew dominant. The week following publication, those findings fed into the federal policy announced Aug. 12 to authorize third shots for the roughly 3% of U.S. residents who are immunocompromised. UCHealth started providing 3rd doses of the mRNA vaccines for immunocompromised patients on Aug. 16.

Renae Jacob, 52, wasn’t – and won’t be – among them, but only because she’d already had her third shot. Her type-1 diabetes led to a kidney transplant and two islet-cell transplants over the past decade or so, and to avoid organ rejection, she’ll take immunosuppressant drugs twice a day the rest of her life, she says. The Denver resident got her second Moderna jab on April 1. She noticed that, unlike after past vaccinations, she felt no side effects. And indeed, an antibody test soon thereafter came up empty.

She was far from alone in seeking a third shot on her own, and she landed one at a public mass-vaccination site in late April. This time, fever, chills, and malaise she’d been hearing about creeped in, and an antibody test a month later showed that the third time was indeed a charm.

Perhaps it will be too for all the immunocompromised poised for their third shots – and for the rest of the vaccinated who line up for boosters come fall. But in the meantime, Jacob says, she hopes the roughly 40% of the U.S. population who have yet to receive a single vaccine dose rolls up their sleeves en masse.

“There are people out there who are vulnerable for whatever reason,” she said. “Kids under 12 are vulnerable. I just feel like it’s our duty as members of society to get vaccinated.”

Booster shots won’t end the contradictions of COVID-19 – not least of which is the ethics of giving third shots here when less than 20% of the global population has been fully vaccinated not due to hesitancy but rather availability. But barring a surprise as big as anything the coronavirus itself has foisted upon us, boosters are coming, and we’d be well-served to view the luxury of rolling up our sleeves again as a blessing as well as a duty.

About the author

Todd Neff has written hundreds of stories for University of Colorado Hospital and UCHealth. He covered science and the environment for the Daily Camera in Boulder, Colorado, and has taught narrative nonfiction at the University of Colorado, where he was a Ted Scripps Fellowship recipient in Environmental Journalism. He is author of “A Beard Cut Short,” a biography of a remarkable professor; “The Laser That’s Changing the World,” a history of lidar; and “From Jars to the Stars,” a history of Ball Aerospace.

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