Making sense of the messiness of omicron

Omicron's fast-moving wave has forced us to learn about this variant's quirks at the same time it's causing explosive case rates around the world. Each country has a unique set of circumstances, including different percentages of the population with immunity from vaccination or prior infections, making it even harder to extrapolate patterns.

As experts learn more about this particular variant of SARS-CoV-2—including changes in the speed of infection and immunity evasion—guidance on behaviors like testing and isolation is adjusted which can be very confusing for the public.

In the U.S., a confluence of factors is complicating our understanding of omicron:

• Two different strains of COVID—omicron and delta—are ripping through the population during a time of year when other viral illnesses like flu and RSV are circulating
• Testing remains limited
• Unlike delta, omicron seems to cause much higher numbers of breakthrough cases in vaccinated people
• Vaccination statuses range from unvaccinated to fully vaccinated and boosted, which means it's nearly impossible to craft one-size-fits-all guidance

In this Q+A, experts from the Johns Hopkins Bloomberg School of Public Health address some common questions and scenarios with what is known right now. All advise some important actions right up front:

• If you're not yet vaccinated, start the process now
• If you don't feel well, stay home as much as possible and seek testing if you can
• Wear a mask when out in public and avoid high-density indoor spaces until test positivity rates in your area come down to less than 1%

Is omicron infecting children at higher rates than previous variants? Is it causing more severe illness for children?

Data from South Africa show that hospitalization rates for children went up with omicron, but this doesn't necessarily mean the variant itself makes kids sicker.

Rather, what we're seeing is more likely the result of an extremely transmissible virus infecting huge numbers of unvaccinated people—including children who either aren't yet eligible or who haven't been vaccinated. By the numbers alone, more cases will mean more hospitalizations.

It's also possible that kids are getting greater exposure—higher viral loads—from extended time at home with infected family members, says David Dowdy, an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health, in a recent Nature article. "Everyone is focused on the pathogen here, but it's not just about the variant, it's also about the host and the environment."

Are infections from omicron milder than from other variants?

Overall, there seems to be less severe disease, but hospital data show that the vast majority of COVID-19 patients in care are unvaccinated. This means that unvaccinated people should assume that omicron is just as dangerous as other variants, says Andrew Pekosz, a professor of molecular microbiology and immunology, in a recent episode of Public Health On Call.

Vaccinated people and those with recent prior infections may have a milder course of illness thanks to the level of immunity they have.

It's also possible that we will eventually see more hospitalizations just given the sheer number of cases, says Shaun Truelove, an associate scientist in international health and a contributing researcher to the COVID-19 Scenario Modeling Hub, in a recent episode of Public Health On Call.

Is it ok to end isolation five days after a positive test if I don't have symptoms?

CDC guidance on this point has been in flux and differs depending on several circumstances, including best practices for the general public and whether or not you are up-to-date on COVID-19 vaccinations.

To calculate isolation and quarantine based on your individual circumstances, follow the prompts on the CDC's chart here.

How many days after a known exposure should you test yourself for the best results? If it's negative, should you test again and if so, when?

Official guidance says if you're fully vaccinated and boosted, there's no need to test for infection following exposure unless you have symptoms. However, rapid home tests have become a valuable tool in helping people make decisions like whether to attend gatherings or visit with someone who is high-risk.

Keep in mind that negative test is only a snapshot of a moment of time and is reliable for only a short period of time. "I have been telling people to test as close to the [upcoming] event as possible," says immunologist Gigi Gronvall, associate professor of environmental health and engineering and senior scholar at the Center for Health Security.

If you're unvaccinated or not yet fully vaccinated, the CDC advises that you get tested on days four, five, or six following exposure if you have no symptoms. If you do have symptoms—which can range from a scratchy throat to a headache—seek testing immediately.

See the latest CDC guidance on exposure and testing here.

Should people be swabbing their noses and throats for home tests?

It is possible that, in early stages of infection, omicron is more present in the mouth and throat than in the nose. Gronvall says more data is needed to confirm this.

Still, swabbing your throat and then your nose, especially if you have a sore throat, could help catch more viral particles and increase the accuracy of the test result, though the FDA advises that these tests were not made for this purpose.

The key is to make sure you don't swab only your throat. Always swab both nostrils with every test for best results.

Why are KN95 masks more protective against omicron than cloth masks?

Cloth masks can filter larger droplets, but medical-grade surgical masks, such as N95s, can filter both large droplets and the smaller aerosols or particles carrying airborne virus from infected people.

One theory about omicron's transmissibility is that it's possible for a smaller dose of particles to infect someone, Pekosz says.

To mitigate this potential risk, wear a mask that reduces both the particles you exhale and those you inhale, which means one that fits well.

Do rapid tests detect the omicron variant as readily as other COVID-19 variants?

Rapid tests, or antigen tests, are generally slightly less sensitive than PCR tests at picking up COVID-19 infections, and there's some suggestion that these tests could be less likely to catch an infection from omicron—especially if it's early, Gronvall says.

If you have symptoms but get a negative rapid test result, don't assume that you're not infected. You may need to test again or get a PCR test.

Is it possible that once we get past this peak of omicron in the U.S., we could be closer to the end of the pandemic?

There are hopes that COVID-19 will eventually shift from pandemic to endemic, meaning there is enough immunity around the world to reduce COVID to a seasonal illness like flu.

Omicron may grease the wheels of that process a bit, especially in countries with high levels of vaccination and immunity, but it's important to remember that there are still vast numbers of people around the world who have not been vaccinated. Low levels of vaccination can also contribute to new variants that could be more lethal or have more immune-escape capabilities, Pekosz says.

In short: Until the majority of the world's population is vaccinated, it will be difficult to get COVID-19 fully under control globally.