What Are the Facts on Omicron? The Picture Is Getting Clearer

Omicron poses a serious threat, but we’re not back to square one

Dr. Tom Frieden
6 min readJan 24, 2022


Photo: Mat Napo / Unsplash

Omicron has quickly supplanted Delta to become the dominant variant in the United States after spreading widely in South Africa, the United Kingdom, and other parts of the world.

In the past couple of weeks, Covid cases have set records in the U.S. — reaching almost triple the number of infections of last January’s peak. Although it appears that we may have hit a peak nationally, there’s still A LOT of virus in the air, and in many places the deluge hasn’t yet crested.

The Omicron “wave” is more like a flash flood or tsunami. In my more than 30 years of experience in infectious diseases, I’ve never seen a virus THIS transmissible — but the good news is that it appears to be much less severe — on an individual basis — than previous variants, and vaccines continue to protect extremely well against hospitalization and death. The virus has adapted, so we must also adapt our response … to Omicron, and to whatever comes next, also.

As both cases and hospitalizations have risen in the U.S. throughout the past few weeks, I’ve addressed some of the most common questions concerning the variant, what it means for the U.S. health system, and ways we can mitigate spread of the virus.

What’s different about Omicron?

Omicron caused a lot of concern when it emerged because of the large number of mutations it contains, which have changed the way it behaves. The variant spreads faster and is better able to escape immunity — at least to infection if not severe disease — than previous variants.

For example, studies of household contacts find a higher risk of transmission — maybe as much as double — when a case is caused by Omicron compared with one caused by Delta, a striking finding.

Is Omicron milder?

Although Omicron is one of the most infectious viruses ever, the good news is that it appears to be significantly less dangerous than previous variants on an individual basis. Having said that, it’s important to be very clear that the speed of transmission and sheer number of infections pose an acute and serious threat to our healthcare system.

Based on what we know now, people who get infected with Omicron — especially vaccinated individuals — are far less likely to experience serious symptoms or require hospitalization. Data suggest that Omicron may be roughly as severe as influenza from a population perspective, and much less so for those who are up-to-date on vaccination.

It may be that the virus is encountering more population immunity than earlier in the pandemic — in many places, 90% or more people have already either been infected with Covid or vaccinated against the virus.

Unfortunately, because Omicron is so contagious, it is still a very serious threat to our healthcare system. Even though a smaller proportion of people infected with Omicron require hospitalization, the sheer number of people being infected with the variant is enough to inundate hospitals throughout the U.S. with a flood of patients.

And at the same time cases are at record levels, our health care system capacity is less because health workers are tired from years of emergency or aren’t able to work at all because they have Covid themselves. (And hey, how about cutting CDC a break from time to time. They saw this coming and quickly and appropriately adjusted recommendations for health care worker isolation and quarantine, shared the evidence for this, and disseminated it widely to health care providers.)

Do vaccines still work against Omicron?

Vaccines continue to provide excellent protection against severe disease from Covid, and that hasn’t changed much with Omicron.

What HAS changed is that Omicron is better able to evade immunity to some degree and cause infections in people who have already had Covid or even those who have been vaccinated more than 3–4 months earlier. Our vaccines did a good job of reducing risk of infection and transmission with previous variants, but it’s not clear this is a realistic goal anymore.

Early data from lab studies showed a reduction in antibody neutralization of the virus compared to earlier variants, and those data have been backed up by new real-world evidence. Unfortunately, reinfection is more likely with Omicron than with Delta.

Although Omicron is causing more infections in vaccinated people, unvaccinated people face the most risk from Omicron. A new CDC study published Friday found that unvaccinated adults had a five times higher risk of infection in December compared with adults who were up-to-date on vaccination. And data from New York show that most of those hospitalized from Covid are unvaccinated. Despite Omicron’s increased immune evasion, vaccine protection against both hospitalization and death remain remarkably high, and a booster dose strengthens your protection.

It’s important to get up-to-date on your vaccination. Other effective, low-burden mitigation tools, particularly masks, are also necessary, at least until the Omicron tsunami passes.

Will getting Omicron protect me against future variants?

We don’t know if infection with Omicron will protect against some, all, or no future or past variants of SARS-CoV-2. With many infectious diseases, less severe illness is associated with less development of immunity, so it’s not clear that the Omicron flash flood will substantially strengthen our wall of immunity much, though it’s possible that it will.

In a very small study from South Africa, antibodies from people recently infected with Omicron could neutralize the Delta variant in the lab. However, what this will mean in the real world, and especially for long-lasting protection is unclear.

Even though we don’t know for sure if Omicron infections will cause effective or long-lasting immunity, we do know that increased vaccination and infection are strengthening our defenses against Covid.

I’m more optimistic about our ability to tame the pandemic than at any point since its emergence — unless, of course, a worse variant emerges, with the infectivity of Omicron and as deadly as Delta. That’s possible, but doesn’t change our ability to move forward if we vaccinate, mask, strengthen public health, and increase vaccine production capacity.

What else can I do to avoid getting infected with Omicron or spreading it?

There are simple steps each of us can take, in addition to vaccination, to reduce our individual risks:

  • Consider upgrading to more protective masks such as an N95, KN95, KF94, or equivalent.
  • Improve ventilation by opening doors and windows, filtering air, or spending more time outside.
  • Before gathering indoors with friends and family you don’t live with, consider getting tested.
  • If you’re exposed to Covid, quarantine and test.
  • If you test positive or have Covid, stay home and isolate to protect those around you.
  • Take extra precautions before visiting vulnerable, elderly, or immunocompromised contacts.

We can’t prevent every infection, but we can make a big difference

Omicron poses a serious threat, but we’re not back to square one. We’ve got vaccines, masks, tests, treatment, and ventilation. Get vaccinated and boosted, mask up indoors (and up your mask game to an N95 or similar if you’re immunosuppressed or elderly), get tested if you are exposed to the virus or feel sick, and balance the potential risks and benefits of activities until the floodwaters recede in the next month or so. Do what matters most to you, as safely as possible.

Let’s learn from the lesson of Omicron — this virus moves fast. Mutations are, in effect, innovations by the virus. Omicron may not be the last surprise this virus throws at us. If anyone insists they know what’s coming next with Covid, they simply don’t know what they’re talking about. To blunt the spread of disease and death, we need to learn quickly, adapt our response, communicate well, and act on what we know.



Dr. Tom Frieden

President and CEO, Resolve to Save Lives | Former CDC Director and NYC Health Commissioner | Focused on saving lives. twitter.com/drtomfrieden