Breakthrough COVID-19 infections helping drive positivity rates

With the omicron variant spreading rapidly throughout the population, the rate of breakthrough COVID-19 infections among fully vaccinated New Yorkers has skyrocketed, helping drive Long Island’s soaring positivity rate, state officials and medical experts told Newsday.

While the COVID-19 vaccines continue to prove effective against serious disease and death, their ability to block infections — particularly in the face of the highly contagious omicron variant — has waned significantly for those who haven’t gotten a booster shot, experts said.

At the end of June, less than 1 out of every 100,000 fully vaccinated New Yorkers had reported a breakthrough infection, compared with 4.5 unvaccinated residents who contracted the virus, according to State Department of Health data.

As of last week, that number had soared to 67.5 out of every 100,000 fully vaccinated residents reporting a breakthrough infection, an 8,300% rate increase since the summer, according to state data released Wednesday. During the week of Dec. 13, about 280 unvaccinated New Yorkers out of every 100,0000 contracted COVID-19, the data shows.

Medical experts said the prevalence of breakthrough infections does not mean the vaccines are not working. Omicron, they note, spreads at two to three times the rate of the delta variant, while the vaccines' power dissipates over time, necessitating a booster to increase immunity levels.

"The vaccines were never intended to prevent all infections," said Dr. Bruce Polsky, an infectious disease specialist and chairman of medicine at NYU Langone Hospital–Long Island, who said breakthrough cases will likely become the norm during the winter surge. "The aim of the vaccines is to prevent illness requiring hospitalization and to prevent death."

Two shots not good enough

Dr. Bruce Farber, Northwell Health’s chief of public health and epidemiology, said breakthrough infections with omicron have become "dramatically more common" among New Yorkers who received only the two-dose Pfizer-BioNTech or Moderna regimen or the single-dose Johnson & Johnson vaccine.

Protection against omicron, he said, now requires a booster shot — and even that may not be enough to completely block transmission.

"This is a seed change because this a different virus, and all the rules that applied to delta and the ancestral strain don’t apply to a virus this contagious," Farber said. "The fact that you’re fully vaccinated is not good enough anymore. That’s a matrix that is no longer particularly accurate or helpful. It’s better than nothing, but that alone is not enough if you look at the way this virus is spreading through our community."

Since the emergence of omicron in New York on Dec. 6, COVID-19 cases among both the vaccinated and the unvaccinated have spiked statewide.

Meanwhile, the vaccine’s "effectiveness" rate against preventing COVID-19 in all age groups has declined from 81% earlier this month to 75%, according to state data. Adding the booster elevates the vaccine’s effectiveness back to more than 80%, even against omicron, experts said.

In total, the state has reported 291,880 breakthrough cases, representing 2.2% of all fully vaccinated New Yorkers ages 12 and older. Officials concede there is a lag in reporting breakthrough case data, meaning the actual number likely is significantly higher.

The state Department of Health could not provide data on Long Island-specific breakthrough infections or how many of those individuals received a booster shot.

But with Long Island’s daily COVID-19 positivity rate at a statewide high of 15.3% in results from Wednesday — even as nearly 82% of the Island's total population has received at least one dose of the vaccine, the highest rate of any region statewide — health officials concede breakthrough infections have become the norm and will continue occurring.

"People have to realize that becoming infected is not equal to becoming sick and intubated in an ICU," said Dr. Bettina Fries, chief of the Division of Infectious Diseases at Stony Brook Medicine. "So although the vaccine may not be able to prevent infection, it still prevents bad outcomes. And that is really important."

‘The perfect storm’

Health officials agree that vaccination, particularly adding a third-shot booster, dramatically reduces the risk of hospitalization or death.

But recent data on COVID-19 hospitalization rates among both vaccinated and unvaccinated Long Islanders — many likely sick with omicron — paints a complicated picture of the vaccine’s effectiveness against the new variant.

As of Dec. 21, 53% of patients hospitalized with COVID-19 on Long Island were unvaccinated, while the status of another 9% was unknown because those individuals refused to provide that information, according to health department data. The remaining 38% are fully vaccinated, the data shows.

The numbers statewide are similar, with 58% of patients hospitalized with COVID-19 unvaccinated, while the status of another 7% are unknown. The other 35% are fully vaccinated, the data said.

State officials contend those figures can be deceptive.

About 95% of all adults statewide — and nearly 83% of the total population — have received at least one dose of the vaccine, according to CDC data. Despite representing a fraction of the total population, the unvaccinated comprise roughly four out of every seven hospitalized patients.

"Based on Department of Health data, the unvaccinated are more than 12 times more likely to be hospitalized than the fully vaccinated," agency spokeswoman Jill Montag said.

As of Dec. 13, just 0.11% of all fully vaccinated New Yorkers ages 12 and older — or a total of 14,383 patients — have been hospitalized with the virus, state data shows.

"The people at the greatest risk of hospitalization are those who are unvaccinated or those who have a reason, because of age, because of immunosuppression or because of an associated condition that makes COVID worse," Polsky said. "Those are the people that we worry most with the breakthrough infections."

Farber said Long Islanders, including the fully vaccinated, should expect conditions to get worse before cases peak, likely early next year.

"It’s a perfect storm," he said. "It’s the holiday. There’s the cold weather. And it’s the vaccine wearing off in general because every week and month that goes by you’re further out from your two vaccines. And then you have a new variant that is not even well-inhibited by those initial vaccines. There’s no huge mystery why this is happening. This is the perfect storm."

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By Robert Brodsky

robert.brodsky@newsday.com@BrodskyRobert

Robert Brodsky is a breaking news reporter who has worked at Newsday since 2011. He is a Queens College and American University alum.