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Throughout the COVID-19 pandemic we’ve seen new variants of  concern of SARS-CoV-2, the virus that causes COVID-19. The World Health Organization gives names to new versions of the virus that it
determines might have more of an impact on people, say by spreading more easily, causing more severe disease, or being better at getting around our body’s defenses. The latest variant making headlines is Omicron.

It was first identified in late November of 2021. But as is always the case with this pandemic, we’re still trying to learn about its effects, and what this new variant means for  the overall course of the pandemic. Here’s what we know right now.

Omicron is spreading quickly, and many experts predict it will overtake the Delta variant as the dominant variant of SARS-CoV-2 worldwide. You or your loved ones might have already been affected by it, given its rapid spread. Part of the reason for the rapid spread is that this version of the virus appears to be more infectious, meaning more likely to spread from person to person, than previous ones.

For example, data from the UK and Denmark suggest that Omicron is more likely than Delta to spread within a household, even in cases where all members of that household had been vaccinated and received booster shots. The Danish study is a preprint, meaning it has not been published or peer reviewed but has been uploaded to a pre-publication server. There’s no guarantee these preprints are correct, as they haven’t been through the usual process of scientific scrutiny, but they are a way to share potentially important information quickly.

We’ll be talking about a few other such studies today. With that out of the way, the reason for the heightened infectiousness might be because Omicron is more adept at dodging the antibody defenses that vaccines give us. Take one lab study, published in the journal Cell, which looked at people who had been fully, recently vaccinated with either the Moderna or Pfizer/BioNTech mRNA vaccines, or the Janssen viral vector vaccine.

Half the people who had been fully vaccinated, but not boosted, couldn’t mount an immune defense against Omicron. On top of that, preprint data out of South Africa suggests previous infection with a different variant of the virus also provides little immunity against Omicron. It also showed that people can become infected more than once.

However, other preprint data suggest that the Janssen vaccine does provide protection against hospitalization, so this one might need more time to untangle. Why? Well, most of these papers focused on the neutralizing antibodies our immune system produces in response to a vaccine or the virus, but that’s not all our immune system does.

So the vaccines may be helping our immune systems protect us from Omicron in other ways. Like the variants that came before it, Omicron has a number of mutations compared to earlier versions, including many that affect its spike protein. These may make it better at both infecting cells, and avoiding antibodies that target the spike.

It also seems to affect different parts of the body compared to previous variants. Preprints from Hong Kong and the UK have found that it’s up to 70 times better at replicating in the nose or upper airway than Delta, which hangs out more in the lungs. More virus particles in the nose and throat could mean it’s easier to sneeze or cough it out and help the virus spread.

Hanging out in the upper airway could also be why this variant seems to cause less severe disease. This also may be why the reported symptoms of Omicron are slightly different: more runny noses and sore throats, and more ear aches, because everything is congested up here. Now, there seem to be fewer hospitalizations around the world for Omicron than Delta, especially for vaccinated individuals.

And when those hospitalizations do happen, people tend to stay in the hospital for around 70% less time regardless of vaccination status, according to one preprint study out of California. Plus, a British report from December 2021 found that the risk of being hospitalized because of an Omicron infection was around a third of the risk for Delta. This was a pretty small study, though, so take the numbers with a statistical grain of salt.

But – and this is a big but – the number of hospitalizations is going up. And quickly. There’s still going to be a subset of people who become seriously ill, even if the variant is milder.

So if case numbers are high, that still represents a large overall number of people who will need hospital care, and who may develop the group of long-term symptoms known as long COVID. The question on a lot of people’s minds now is what Omicron means for the future of the pandemic. One of the big questions is how the virus will evolve.

As in, whether we’ll keep seeing not just new variants, but new variants that are dangerous. Researchers have warned that as the virus continues to spread around the world unchecked, that creates opportunities for new mutations that might turn into a variant of concern. So slowing transmission is as important as it’s ever been.

Fortunately, we’re not back to square 1. We know far more about this virus than we did in early 2020. We know that non-pharmaceutical public health interventions like social distancing, limiting the number of people in enclosed spaces, and testing and tracing policies will continue to play a role in our response.

Some people have predicted that COVID-19 will become an endemic disease. That is, one where the disease is always present in the community and causing infections on some level. However, many other experts point out that that’s not a good outcome, whether or not it’s likely.

Seasonal flu is an example of an endemic disease that still comes with a significant death toll every year. Endemism is also slightly different from herd immunity, which you may have heard discussed. That’s where most people have immunity and the disease can only spread within particular sub-populations who aren’t immune.

And that’s something that experts were never really banking on, despite public figures talking it up. Because this virus is just too good at shifting into new forms for the defenses we get from vaccines, or prior infection, to completely wall it off. It’s different from, say, measles, where vaccination is effective at preventing disease in most people.

But vaccination will still be a valuable tool. Expanding vaccination to as many people as possible worldwide will give the virus fewer opportunities to mutate into new variants, as overall infections decline. Plus, some scientists are using data from all of the known previous variants to try to build predictive models of what might be around the corner.

A recent study in Science Translational Medicine looked at what mutations have helped a particular virus variant spread in the past. The researchers analyzed what features of that mutation helped it spread, and developed a computer model that they used to retroactively predict which mutations have spread up to four months in advance. Now they hope to use the model as a starting point to help us prepare or screen for new variants.

So when it comes to Omicron, we’re not reliving March 2020. But there are also still lots of unknowns, and this is still a dangerous virus. So stay safe, everybody.

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