Omicron is Spreading: Here’s What Our Scientists Know

Jan. 10, 2022

The Omicron variant, which emerged in Botswana and South Africa in November of 2021, made its first appearance in Monroe County on December 22 – around the same time it became the dominant variant circulating in the U.S. Researchers around the world are rapidly collecting data on this new variant, which appears to spread much more easily than previous variants. While a lot of these studies are ongoing, we asked several infectious disease experts at the University of Rochester Medical Center (URMC) what they know so far.

Ghinwa Dumyati, MD

Ghinwa Dumyati, M.D.

Professor in the Department of Medicine (Infectious Diseases) and the Center for Community Health and Prevention at URMC


Ann Falsey, M.D.

Professor in the Department of Medicine (Infectious Diseases) at URMC, and co-director of the URMC Vaccine and Treatment Evaluation Unit


Edward Walsh, M.D.

Professor in the Department of Medicine (Infectious Diseases) at URMC

How much Omicron is in our community?

Dumyati: We should assume that at present most of the cases in our region are Omicron based on data from New York state and the Centers for Disease Control and Prevention (CDC). According to those data, at the beginning of January, the Omicron variant was responsible for roughly 95 percent of COVID cases across New York and the U.S.

How much more transmissible is Omicron?

Walsh: Data so far suggest that Omicron is four times as infectious as Delta, which was twice as infectious as the original strain of SARS-CoV-2. This is probably because Omicron appears to have some level of resistance to immunity. It can infect vaccinated people but seems to cause much milder disease in these people than it does in unvaccinated people.

I’ve heard that Omicron causes milder disease. Is that true?

Falsey: It’s really hard to say whether Omicron causes milder disease in general because studies are based on partially immune populations. Omicron may cause milder disease in people who have some level of immunity – from vaccination or prior infection – but that might not be true for those with no immunity.

Dumyati: Right now, we are seeing an increase in hospitalization and ICU admissions of COVID patients – and it’s mostly driven by unvaccinated individuals.

Do we need new vaccines?

Falsey: While Omicron seems to evade some immunity, our current vaccines still protect quite well from serious disease – particularly following a booster dose. Vaccinated people may get infected, but the infection will likely be mild.

Will we need more booster doses?

Walsh: Right now, a single booster of the mRNA COVID vaccines is sufficient to protect against both Delta and Omicron. However, it is unclear if more booster doses will be necessary in the future. An Israeli study was just launched to investigate whether a fourth dose of these vaccines (or a second booster) improves immunity and protection from COVID.

Will there be more variants? Could this be the beginning of the end of the pandemic?

Falsey: As the pandemic evolves, there will be more variants and more waves of COVID cases. Hopefully, with each new variant and each wave, we will see milder disease – hopefully becoming something like a regular winter cold. But I would hate for unvaccinated people to think they can wait this out. Omicron is still a vicious and unpredictable virus - and I don’t think it will go away overnight. The 1918 pandemic flu didn’t just go away. It circulated until 1957. So, we should remain cautious.

Should I just get infected with Omicron and get it over with?

Walsh: It is very clear from very good studies that immunity from vaccination is more robust and lasts longer than immunity from infection, which is why we recommend that people who have been infected still get vaccinated. And infection is risky – not only for you but for others in our community – especially those who are immunocompromised.

How can I protect myself?

Dumyati: Get vaccinated, get boosted and if you’re going out in public, wear a mask. Surgical or N95 masks are best if you can find them, but what is most important for any mask is that you have a good seal around your nose and mouth. Check out the CDC’s information on masks and respirators.