The omicron variant of SARS-CoV-2, the coronavirus that causes COVID-19, is projected to drive a new spike in infections that could peak in February at more than 150,000 a day in Florida, well above any previous peak since the pandemic began, according to modeling from the Emerging Pathogens Institute at the University of Florida.
Researchers produced four different scenarios that may play out between now and through spring 2022, using different assumptions for how transmissible the omicron variant will prove to be, how severe infections will become, and how well vaccines and naturally acquired immunity will protect people.
While infections could be three times as high as during the delta variant spike in late August and early September, the number of associated deaths may be much smaller if early indications are correct that omicron cases lead to less severe complications.
One reason for that, according to experts, is that while omicron may break through levels of immunity acquired by vaccines or earlier infection, that immunity can protect people from becoming very sick.
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“We are entering an explosive peak in infections. It’s really unfortunate. For this variant, having a prior infection doesn’t appear to be very protective and we have a lot of people in Florida who are not vaccinated,” said Dr. Ira Longini, professor of biostatistics, who participated in the study.
The most likely projection, according to the researchers, anticipates a peak of 150,000 cases per day in February but that includes both symptomatic and asymptomatic cases. The number of reported cases — those confirmed by testing — are expected to peak at about the same time but just over 30,000 cases per day, as most who don’t exhibit symptoms never get tested.
The omicron scenarios
That’s the most likely scenario, the researchers say, but it’s not the only one. Adjusting the three variables researchers considered — transmissibility, severity, and ability to evade immunity — leads to models that show much better or much worse public health outcomes.
In a second scenario, reported cases match the delta peak although actual infections more than double, while associated deaths don’t get above 100 per day — below the level in previous pandemic peaks.
In a third scenario, reported cases are three times the delta peak and daily deaths match it, at about 400 per day.
In the final scenario, reported cases jump above 60,000 per day and the 600 daily deaths are worse than at any previous point since COVID-19 emerged.
The study was done by Thomas J. Hladish, Alexander N. Pillai and Longini.
Dr. Stuart Ray, a professor of medicine at Johns Hopkins University, said the UF modeling study “looks good” but cautioned that the assumptions about the severity of omicron infections might be too optimistic.
“Data from the United Kingdom suggest no significant difference from delta,” Ray said, although even the worst-case scenario in the UF study assumes omicron is less deadly.
He said that lack of good data on omicron is a special concern because it is spreading so quickly that people won’t be able to change behavior as effectively in response.
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Longini said it is too soon to say with certainty which scenario will play out, but it appears the models may need to be adjusted as new data comes in. The omicron variant was only first detected in Florida two weeks ago.
“We might have underestimated a bit the speed of this wave and even its size,” he said.
Even so, the most likely model shows 2.5 million infections in Florida during the first three months of 2022 — roughly a third of all infections since the pandemic began two years ago.
Longini said his team did not even model the worst-case scenario — where transmissibility is high, severity of complications is high, and the variant’s ability to evade immune response is high — because early data indicates severe disease from omicron is not as common as with the delta variant.
“We don’t yet have good, precise data. But we have a lot of people who are susceptible. That why the infection rates are so high,” he said.
He said models developed in advance of the delta variant wave proved to be very accurate, but he has somewhat less confidence in the current modeling for omicron because less is known about this variant than was known about delta leading into that surge in August.
Longini recommended people take precautions, especially to become fully vaccinated, and said if he had out-of-town guests visiting this week — particularly from New York, where the omicron variant is surging — he’d like to see people wearing masks.
Dr. Stuart Ray is the brother of the author of this article.