The coronavirus isn’t done with us yet. It’s a good time to get your bivalent booster.

Oct. 26, 2022
mom with her son who is getting tested for COVID-19.
COVID-19 variants have come and gone in Colorado. The difference between the new boosters and those that came before them is that they’re bivalent, containing mRNA strands of the original coronavirus vaccine as well as those adjusted to match key mutations of omicron variants BA.4 and BA.5. Photo: Getty Images.

With geopolitical unrest, economic uncertainty, and the midterm elections dominating the headlines, it takes some scrolling to get to the latest on the coronavirus. Just because it’s out of sight doesn’t mean it should be out of mind – especially when it comes to getting the latest booster shot.

That shot, like the other mRNA vaccines before it, sends genetic instructions wrapped in fatty nanoparticles into your shoulder-muscle cells. Protein factories in those cells read the mRNA to produce proteins that look just like the spike protein of an actual coronavirus. The body recognizes these harmless, free-floating spike proteins as an invader, and the immune system takes note. When an actual coronavirus shows up, it has lost the element of surprise, reducing the chance of infection and sharply cutting the risk of serious illness.

The difference between these new boosters and those that came before them is that they’re bivalent, containing mRNA strands of the original coronavirus vaccine as well as those adjusted to match key mutations of omicron variants BA.4 and BA.5.

Because the U.S. Food and Drug Administration’s initial emergency authorization for the bivalent boosters only happened on Aug. 31, there’s not yet enough real-world data on the new vaccines’ effectiveness to prove their mettle against those two omicron variants or ones having emerged since (on Oct. 12, the U.S. Food and Drug Administration expanded its approval of the bivalent booster to children as young as 5).

But lab data from mRNA vaccine makers Moderna and Pfizer-BioNTech have shown an improved immune response to the newer omicron strains. That insight, combined with clinical results from a bivalent booster targeting the original BA.1 omicron strain – not to mention billions of vaccinations worldwide with the original mRNA vaccines – satisfied the FDA on the safety-and-effectiveness fronts.

Bivalent vaccine uptake remains low

Yet despite perhaps 80% of current COVID-19 cases in Colorado and nationwide being the BA.5 strain, bivalent vaccine uptake remains low. Just 8.5% of those eligible in Colorado have gotten the bivalent booster (by comparison, 70.3% completed the primary series). While Colorado is doing better than the nation as a whole – just 5.5% of the eligible population has received the bivalent booster – Colorado’s bivalent-booster numbers should be a lot higher, says Dr. Michelle Barron, UCHealth’s senior medical director of infection prevention and control. Among other reasons, she says, is that the holidays are fast approaching.

Dr. Michelle Barron

“It takes two weeks for these vaccines to be effective,” Barron said. “Thanksgiving is less than a month away, so you have two weeks, basically, to make sure you don’t bring something to Thanksgiving dinner.”

The combination of vaccination, widespread past infection, and improved treatments have brought hospitalization numbers way down from their peaks in early 2022, she says – all good news. But the pandemic continues to burn on. While recent nationally reported daily case counts of about 40,000 are just 5% of those of the mid-January peak, underreporting is likely, and the coronavirus is still killing close to 400 people a day around the country. That’s more than three times the pace of U.S. traffic accident deaths, and, extrapolated to annual totals, more than five times the mortality of a typical flu season.

“Even if your opinion is, ‘If I get sick, so what?’ the potential impact to others is huge,” Barron says.

Studies show bivalent booster helps against long COVID

Another reason to get the new bivalent booster is that studies have shown vaccine protection to cut the risk of long COVID. The U.S. government estimates that somewhere between 7 million and 23 million people in the United States have or have had long COVID, and that a million people remain out of work because of symptoms including breathlessness, heart palpitations, chest pain, and “brain fog,” among others. A new study of nearly 100,000 Scottish National Health System patients found that, six to 18 months after coronavirus infection, 6% had not recovered at all and 42% reported lingering symptoms. That study reported some vaccine protection from long COVID, and it also found that asymptomatic infections didn’t lead to long covid.

“We’re seeing, often, young, healthy people with these chronic conditions we don’t fully know how to treat, manage, or even diagnose,” Barron said. “If the vaccine can mitigate long covid, it’s one more reason to do it.”

Bivalent booster aids in continued population immunity

Add to that the inevitability of viral mutations. The most concerning among the current crop of emerging variants is all are children of omicron (unlike the case of omicron itself, which came from a different lineage entirely than the delta variant it abruptly supplanted in late 2021). A particular worry is one called BF.7 (a BA.5 subvariant), which in lab studies has shown a worrying knack for immune evasion. It now makes up about 5% of cases nationally, and its mutations lead Barron to suspect that “it’s like the love child of delta and omicron.”

Dr. Jonathan Samet

It remains to be seen whether, as was the case with delta, BF.7 causes more severe disease than omicron. If so, and if it were to become the dominant strain (it could stall, or other emerging strains could overtake it – one called BQ.1 is expanding quickly in Europe), we could see a nasty winter spike and hospitalizations on the order of those seen early this year, according to a new Colorado Covid-19 Modeling Group report.

“That’s not a surprise – a ‘bad’ variant will send the curve back up. Immune escape and virulence are key,” wrote Dr. Jonathan Samet, dean of the Colorado School of Public Health and leader of the Colorado COVID-19 Modeling Group, in an email.

Samet says the coronavirus pandemic’s path will depend on how the virus mutates and how those mutations spread. If BA.5 remains dominant, widespread immunity from prior infection and vaccination could render the coronavirus an endemic disease manageable like the annual flu. But, Samet says, “Experience to date suggests we will experience the consequences of the next variant(s) – but it’s not clear which one.”

“We are in a good place at the moment, with a high rate of population immunity,” he said. “We need to maintain it by achieving the highest possible level of boosters.”

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.