The omicron surge has peaked and appears to be on a double-black-diamond downslope. Three major metro Denver counties dropped mask mandates in early February. Statewide hospitalizations from this omicron-driven coronavirus wave peaked at 1,676 in mid-January and stood at 1,012 as of Feb. 8, a number the Colorado COVID-19 Modeling Group expects to fall to below 500 by the end of February.
Vaccination is a big part of the story: 68% of the state’s residents are “fully” vaccinated, which is among the top one-third nationally. Those quotation marks are there because, with a coronavirus variant as contagious as omicron, it’s really about the COVID-19 vaccine booster, and only about 48% of residents have had that third shot.
Perhaps a bigger part of the story is just how many of us have been infected with omicron and how many more of us will soon join them. The aforementioned modeling group estimated that, as of Jan. 25, about 42% of Colorado residents had already gotten omicron. Despite cases having peaked, the ride back down will take about a month, during which that figure will rise to 65% by late February, the group estimates. By midmonth, they estimate, 80% of residents will, through SARS-CoV-2 exposure, vaccination, or both, be immune to the variant. The end of the coronavirus pandemic feels near.
The end of coronavirus felt near after the widespread introduction of vaccines a year ago, too, and then came the delta variant, and then omicron. Two years into the coronavirus pandemic, we have learned not to declare victory over this cursed microscopic foot-massager. So where are we, and where might the coronavirus pandemic be headed? To find out, UCHealth Today talked to three UCHealth and University of Colorado School of Medicine experts: Dr. Jonathan Samet, dean of the Colorado School of Public Health and leader of the Colorado COVID-19 Modeling Group; Dr. David Beckham, a CU School of Medicine virologist and infectious disease specialist; and Ross Kedl, PhD, a CU School of Medicine immunologist and vaccine specialist. All work and do research on the Anschutz Medical Campus.
Will COVID ever end or go away?
“If ‘go away’ means permanently gone, I think that the answer is no,” Samet said. “We already have routinely circulating coronaviruses that contribute to the common cold, and SARS-CoV-2 now has animal reservoirs like influenza does.”
Samet added, though, that near-universal immunization with vaccines capable of conferring prolonged immunity could change that.
Speaking of animal reservoirs, with the coronavirus’s spread in animal populations – in mink farms and among hamsters and deer, for example – is there a risk of it mutating among animals and jumping back to humans?
It’s a low risk, Beckham says, and others agree. SARS-CoV-2 was attuned to invading human cells and skirting the human immune system’s defenses from the beginning, and it’s gotten better at it since.
“The likelihood of this same virus jumping back from an animal reservoir is pretty low,” Beckham said. “I think it’s just going to continue to circulate in people. It’s become a people virus.”
With the rapid spread of the omicron variant, you hear about the coronavirus transitioning from a pandemic to an endemic phase. What does that mean?
While “there is no particular quantitative definition,” Samet says, “endemic means that the virus is with us and causing sporadic cases and outbreaks but not the surging wave of an epidemic.”
Epidemiologists consider “endemic” to mean the rate of infection in a population is neither increasing or decreasing over time, Beckham says. “You basically have a reproductive rate, or R0, of one,” he says. “It’s just maintaining itself.”
While that sounds better than “pandemic” (which is a border-spanning epidemic), endemic doesn’t always equate to benign, he says. Ebola, dengue, and malaria are endemic diseases, and malaria alone infected 241 million people and killed 627,000 in 2020 alone.
Kedl says another difference between an epidemic/pandemic and endemic disease has to do with control.
“An epidemic is one that we really have little control over. It’s rising and falling at rates that we can’t really pull the dial on,” he says. “With endemic disease, we have some degree of control, or a significant degree, such that all you really expect are limited outbreaks that don’t go rampant across the population in an uncontrolled fashion. And that essentially describes the flu, right? It doesn’t rage out of control, with the exception of something like the 1918 version.”
Will immunity from omicron, delta, alpha, the original strain, and so on protect us from future variants?
Another way to phrase that is whether there’s a broadly neutralizing immune response that tunes into different coronavirus variants, Beckham says. The science so far shows that while such a cross-reactive immune response happens with the coronavirus, its strength depends on how one was exposed.
Those who recovered from severe disease “developed a nice, robust, long-lasting immune response that was protective,” he said.
But those who had mild or even moderate disease saw a more variable immune response, meaning that protection dropped off after just a few months.
“That variability is the reason why, after infection, we still recommend that people get vaccinated, because the vaccine does result in a long, durable kind of immune response,” Beckham says. “Natural immunity does not equal protection. There’s a lot of variability there. So, going out, getting COVID, and thinking you’re done with it is probably not the way to think about this, because we definitely know people with milder infections don’t develop great immune responses, and a vaccine is definitely protective for those people.”
That vaccines developed for a now-extinct SARS-CoV-2 variant still work so well is an indication that immunity to one coronavirus strain extends protection to others, Kedl adds. Those infected with omicron may enjoy a strong immune boost, he adds. Its many mutations – 30 on the spike protein alone – suggest that “It went in a number of different potential variant directions at once.”
“And so whichever direction the virus goes next, we may already be partly down that road to some degree in terms of our immunity,” Kedl said. “So omicron may have given us some potential advantages, even for the next variants. Time will tell whether that’s true or not.”
How does immunity differ among those who were vaccinated versus those who’ve recovered from a coronavirus infection?
The original doses of the vaccines or a severe infection offer about 50% protection from repeat infection, and vaccines are highly effective at keeping people from getting sick enough to be hospitalized, Beckham says. While omicron is contagious enough to make repeat or breakthrough infections more common – remnant antibodies aren’t bountiful enough in the nose and throat to stop the virus from gaining a foothold – the more durable T-cell and memory B cell responses remain robust and appear to be preventing serious disease in those who aren’t immunocompromised “for months and months, even against omicron, especially after boosting.”
Kedl says the combination of vaccination and infection “is incredibly potent, and not only elevating your level of immunity, but also the breadth of your immunity because it’s influenced both by the vaccine, which was for the original strain of virus we haven’t seen for two years, and whatever strain you got infected with, so it broadens your immune response.”
Such hybrid immunity (in technical terms, a heterologous prime boost), he says, “is a really, really powerful way of elevating your immunity.”
Kedl adds that vaccine effectiveness should be measured in terms of preventing severe disease – not in preventing infection.
“The primary goal behind vaccination is to protect you from the most severe consequences of infection, independent of whether it stops you from getting infected or not,” Kedl said. “Using this more appropriate definition of efficacy, the vaccines have been amazingly protective, no matter what strain you look at. That said, studies have shown that fully vaccinated and boosted individuals are also highly protected against any infection at all, even from Omicron. That’s just icing on the cake.”
Let’s say you had the initial two-shot course of the Pfizer or Moderna vaccine, skipped the booster shot, and then came down with Omicron. Should you get a booster now?
Yes, Kedl says.
“If you hadn’t been boosted and got a breakthrough infection, I’d get another shot and kick that immunity up as high as possible, because the virus is not leaving.”
Will we ever stop wearing masks on airplanes? More generally, will wearing masks ever become a distant memory?
“I can’t speak to forever, but for now, using a respiratory protective device in crowded settings is reasonable,” says Samet, who wears an N95 respirator when he travels to protect himself and others.
Beckham says it’s about calculating risk. Are you inside in close quarters? Are virus levels high? (In Colorado at the moment, that’s the case: Samet’s modeling group estimates that one in 19 people are infected with omicron.) Are you at high risk of severe outcomes due to age, immune status, or vaccination status? Then consider a mask. If not, perhaps not.
“Maybe there will be periods where we don’t need masks, but I think you have to be flexible with the masking, depending on what’s going on in the population,” he said.
Kedl agrees with Beckham on the importance of evaluating one’s own risk.
“Show me where in the data it indicates any serious risk for a vaccinated and boosted person under 65 years of age who is in good health and with no risk factors,” Kedl said. “I’ll save you the time: There isn’t any.”
But, he adds, if you’re a 79-year-old with type 2 diabetes visiting a busy indoor place, masking may be the right choice even if you are vaccinated and boosted.
“We have been outsourcing decisions about masking up,” Kedl said. “Those decisions now need to be attended to by each and every one of us, and I think we need to be considerate with each other as we work through those decisions.”
What’s next for the coronavirus? There will be new variants. Is there any way to predict what new variants might bring as far as transmissibility and disease severity?
“The natural direction for viruses to head is in a more contagious, less virulent direction,” Kedl said.
While there’s no reason that the next strain couldn’t be more virulent (that is, causing more severe disease), the coronavirus doesn’t gain anything by mutating in that direction.
“These viruses, they honestly don’t care if they make you sick,” Beckham says. “They don’t care if you’re in the hospital. What they’re trying to do is infect you and then spread within the first five to seven days of that infection. That’s where the selection pressure is.”
Samet agrees: “Transmissibility and immune escape give advantage to a variant, not virulence,” he said.
The coronavirus has followed the natural direction Kedl describes. Delta was twice as transmissible but no less virulent than alpha; omicron is twice as transmissible and less virulent than delta; and the BA.2 omicron subvariant is perhaps half again as transmissible as omicron but does not appear to cause more severe disease.
“It’s always possible, of course, to spin out a really dangerous variant. It’s just not very likely,” Kedl says. “The less virulent they are, and the more contagious they are, the more likely they are to spread and to take over. And as a result, the immunity you develop against those are likely to make you resistant to a more virulent and/or less contagious strain. Those will just lose based on math.”
Looking ahead, how do you think vaccinations will happen? Will they be like childhood vaccines? In the same syringe as the flu shot? Will we need vaccines at all?
The need for repeated vaccination will depend on how long-lasting protection against serious disease lasts, Beckham says.
As the coronavirus becomes endemic, severe disease – not just case counts – becomes the key metric.
“It may just be that you’re really well protected against severe disease and we never need another booster,” Beckham said. “We just don’t have that data yet.”
Kedl’s best guess is that SARS-CoV-2 will turn into another of the four current seasonal coronaviruses that cause common colds, and that vaccination will be along the lines of what we do for seasonal flu. Vaccination approaches will also depend on the nature of variants and the illnesses they cause.
“The rate of variant generation is really, in my view, what will guide the frequency of boosting from here on out,” Kedl said. “My bet is that, for the next 10 years, every couple of years, there’ll be a new variant booster that you can get. And so, I would think, you would couple that with your flu vaccine, and you’re good to go.”