Are you ‘fully vaccinated’ against COVID? Omicron may change that.

The omicron variant threatens to unleash a new COVID-19 wave that could reveal the fully vaccinated aren’t as protected as they once were.

In Florida, 62 percent of the population — more than 13.4 million people ages 5 and up — is fully vaccinated, according to the Centers for Disease Control and Prevention. The CDC and Florida health officials define that as anyone who got two doses of the Pfizer or Moderna vaccines or one Johnson & Johnson dose.

But that immunity starts to wane three to six months after vaccination, while booster shots aren’t usually recommended until after six months. That gap could leave millions of vaccinated Floridians vulnerable to infection — especially the elderly and immunocompromised. Then there are the millions of unvaccinated who might have little protection against omicron, which may be the most contagious COVID-19 variant yet.

That’s according to a recently published paper co-authored by University of South Florida epidemiologist Jason Salemi. “When you see the CDC reporting really high vaccination numbers,” he said, “that’s not really giving the full picture.”

The paper aligns with public health experts who say the definition of “fully vaccinated” should change to reflect when you were vaccinated and whether you got the booster.

“Think of someone who gets infected six plus months after their Pfizer or Moderna shot,” Salemi said. “That’s a very different picture than someone who just got their booster or just got immunized.”

Six million Floridians are unvaccinated, according to the CDC. And there are 6 million vaccinated residents whose immunity may be waning because they’re overdue for their booster, according to Salemi’s calculations. Add those up and that could leave roughly 56 percent of Florida’s population vulnerable to omicron.

That portends more suffering for a pandemic-weary nation already enduring a delta surge in the Midwest and Northeast. The U.S. can look to Britain to see its potential future. There, omicron cases double every 3.7 days, and officials estimate it will become the dominant variant in that country next week.

In the U.S., experts estimate omicron could become the dominant strain as soon as January.

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The world knows a lot more about the omicron variant now than it did five weeks ago when it was first identified by South African researchers. Omicron appears to be more infectious than any previous variant, including delta. It also has a shorter incubation time and is better at evading the body’s immune system.

Four recent laboratory studies from Australia, Germany, Israel and the U.S. confirm that all three vaccines approved in the U.S. are substantially less effective against the omicron variant, especially in individuals who completed primary vaccination over six months ago.

Omicron is even more of a threat to the unvaccinated, and prior infection may not provide much protection. Most South Africans have already been infected by COVID-19, but The New York Times reports that researchers there found that omicron poses five times the risk of reinfection compared to other variants.

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However, omicron appears to be less virulent than the delta variant, producing fewer severe illnesses and hospitalizations. In parts of South Africa, the number of COVID-19 patients in the intensive care unit or on ventilators is 50 to 70 percent lower than during the delta wave, according to the Financial Times, and those who are vaccinated seem to fare better when infected.

Researchers, however, are still evaluating the threat that omicron poses to determine if it is more or less virulent and deadly than delta. It’s too early to assess the dangers of omicron, said University of Miami epidemiologist Mary Jo Trepka, but “It’s very clear that vaccination is our best defense.”

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But that defense isn’t perfect and needs reinforcements.

Researchers have long known that the protection provided by the COVID-19 vaccines wanes over time. But omicron has upended the scientific understanding of who is “fully vaccinated,” and thus protected, according to the Dec. 9 paper Salemi wrote with epidemiologist Elizabeth Pathak, president of the Women’s Institute for Independent Social Enquiry. It has not yet been peer reviewed.

The question of who is fully vaccinated also has grown more complicated as the U.S. government keeps expanding the pool of people who should get booster shots. Everyone ages 16 and over is eligible for a booster six months after their last shot, yet the CDC does not require the extra dose to be considered fully vaccinated.

Johnson & Johnson users represent another complication: Their immunity wanes even faster. The latest guidelines call for them to get a second Johnson & Johnson dose, or one of the other vaccines, two months after the initial dose.

The population of who should get extra doses will likely keep growing as researchers determine whether younger people will need boosters and whether the vaccinated should get another booster.

But only 27.2 percent of the U.S. population — and 26.2 percent of Florida’s — have been boosted.

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On top of all this, Pathak and Salemi outlined another reason to be concerned about omicron: The way state and federal health officials collect COVID-19 data means we have no way of knowing who among the vaccinated are most vulnerable.

This can frustrate population-level studies that try to estimate how infectious and harmful the new variant is.

One recent study from South Africa’s largest private health insurer illustrates the problem. The study found that the Pfizer vaccine was much less effective protecting against infection and hospitalization from the omicron variant compared to delta.

The vaccine, it found, has fallen from 80 percent effective against infection during the delta wave to 33 percent against omicron.

Likewise, the vaccine has fallen from 93 percent effectiveness against hospitalization during the delta wave and is now 70 percent effective there.

But the study does not indicate when individuals were vaccinated, and the reduced efficacy of vaccines may be “potentially compounded by waning durability,” according to the study’s authors. The study does not account for those who were previously infected with an earlier version of the virus, either. There are also few booster shots available in South Africa, The New York Times reported.

• • •

The solution to this problem could be more nuanced data reporting, according to Salemi and Pathak. They suggest implementing four categories to more accurately reflect an individual’s effective immunity:

• Not immunized: The unvaccinated.
• Partially immunized: Those who got one dose of either two-part mRNA vaccine.
• Optimally immunized: Those who got the Johnson & Johnson vaccine in the past two months, or the two-dose vaccines in the past six months, or who received a booster shot.
• Immunized with waning immunity: People overdue for a booster.

At the moment, no one can say how many Floridians are overdue for a booster shot using the weekly COVID-19 data released by the state. The Florida Department of Health only releases the number of residents who are partially vaccinated, fully vaccinated and boosted. It does not report how many are due for a booster.

At the county level, the picture is even worse: The state only reports those who got one dose as “vaccinated” — it doesn’t report how many received a second dose or booster shot.

The CDC reports partial and full vaccination numbers at the county level, but it does not calculate how many people have waning immunity.

The Tampa Bay Times has spent weeks asking both state and federal officials to release case, hospitalization and death data by vaccination status for Florida. Both have repeatedly declined to do so, citing medical privacy concerns.

The goal of policymakers should be getting the right information to the right people, said Trepka, the University of Miami epidemiologist.

“Right now, it’s not easy for local policymakers to tell what share of people are fully protected and what share have waning immunity,” she said.

• • •

Not everyone agrees that health agencies need to make public the distinctions about who is partially or optimally immunized to the public.

“What (Salemi) is proposing is totally correct for us scientists,” said University of Washington epidemiologist Ali Mokdad, “but as terms for the public (to understand), better something simple.”

Mokdad suggests classifying as fully vaccinated anyone who got three doses of Pfizer or Moderna, or two doses of Johnson & Johnson. “Use this definition and nothing else,” he said. “You are either fully vaccinated or not.”

An updated definition of fully vaccinated may be coming soon. Changing the definition to include a booster shot is a “matter of when, not if,” National Institute of Allergy and Infectious Diseases director Dr. Anothony Fauci said in a Dec. 8 interview on CNN.

Overhauling the definition of “fully vaccinated” may be overkill, said University of Florida epidemiologist Ira Longini Jr. “It seems to say that waning immunity is an all-or-nothing, and that is a very strong assumption. In reality, we know that immunity is a sliding scale that falls as you get further away from vaccination.”

Booster shots can improve protection, he said, but it’s not clear yet for how long. “Saying everyone should get a booster is a bit of a blunt instrument, and I’d rather send those doses overseas where they’re needed.”

Still, Longini agrees that more detailed data can help inform where to focus vaccination efforts.

Florida officials are not actively encouraging vaccinations or booster shots. Gov. Ron DeSantis says the decision to get vaccinated is a personal choice, and on Nov. 18 he signed four bills into law that offset federal mask and vaccine mandates. President Joe Biden’s attempt to impose a vaccine mandate on large employers, encompassing 100 million Americans, is being challenged in federal court and only covers some states.

But health experts say the best defense against omicron, and future COVID-19 variants, is to get vaccinated and get boosted on time.

”Otherwise, people should do what they have control over,” said Trepka, “wear a mask and avoid large groups of people indoors.”

How protected are you?

Epidemiologists Elizabeth Pathak and Jason Salemi co-wrote a Dec. 9 paper questioning the definition of who is “fully vaccinated” in the face of waning protection and say these categories more accurately reflect a person’s effective immunity:

• Not immunized: The unvaccinated.
• Partially immunized: Those who got one dose of either two-part mRNA vaccine.
• Optimally immunized: Those who got the Johnson & Johnson vaccine in the past two months, or the two-dose vaccines in the past six months, or who received a booster shot.
• Immunized with waning immunity: People overdue for a booster.

• • •

How to get vaccinated

The COVID-19 vaccine for ages 5 and up and booster shots for eligible recipients are being administered at doctors’ offices, clinics, pharmacies, grocery stores and public vaccination sites. Many allow appointments to be booked online. Here’s how to find a site near you:

Find a site: Visit vaccines.gov to find vaccination sites in your zip code.

More help: Call the National COVID-19 Vaccination Assistance Hotline.

Phone: 800-232-0233. Help is available in English, Spanish and other languages.

TTY: 888-720-7489

Disability Information and Access Line: Call 888-677-1199 or email DIAL@n4a.org.

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Tampa Bay Times coronavirus coverage

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BOOSTER SHOTS: Confused about which COVID-19 booster to get? This guide will help.

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PROTECTING SENIORS: Here’s how seniors can stay safe from the virus.

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