The omicron variant has infected nearly 800,000 New Yorkers who were vaccinated against COVID-19, as the highly contagious coronavirus strain fueled debate over the pandemic’s next chapter.
The so-called breakthrough infections of vaccinated New Yorkers were reported between Dec. 13 and Jan. 17, while omicron replaced the delta variant as the state’s predominant strain, according to USA TODAY Network New York analysis of state data.
The breakthrough cases accounted for nearly half of the 1.7 million total coronavirus cases during the same period.
The findings in part reflected how 73% of New Yorkers are vaccinated and present a larger share of potential virus hosts. They also underscored why authorities say omicron has proved much more effective at evading vaccine protection against infection than prior variants.
Further, about 17,100 vaccinated New Yorkers were hospitalized due to COVID-19 during the same period, though some of these cases could be linked to the delta variant due to lags in infected people reaching hospitals.
Before the month-long explosion of omicron-related infections, the tally of breakthrough cases in New York totaled about 227,000 during the roughly 11-month rollout of COVID-19 vaccines, state data show.
Meanwhile, the overall number of breakthrough cases, which now topped 1 million, corresponds to 7.7% of the population of fully vaccinated people 12-years or older.
How COVID breakthrough cases impacted policy
Despite the rising breakthrough infections caused by omicron, authorities and health providers said unvaccinated New Yorkers remained at higher risk of severe illness and death than the vaccinated.
Hospital leaders and health officials, for example, have said most COVID-19 patients filling intensive care units during the omicron wave are unvaccinated.
Beginning the week of Dec. 13, state research also shows COVID-19 vaccine effectiveness against cases began to decline. But in the most recent week, vaccine effectiveness was still 77.8%, state data show.
This means fully vaccinated New Yorkers had about a 78% lower chance of becoming a COVID-19 case, compared to unvaccinated New Yorkers.
Further, fully-vaccinated New Yorkers had between a roughly 90% and 97.5% lower chance of being hospitalized with COVID-19, compared to unvaccinated New Yorkers, state research found.
The public-health policy ramifications of omicron’s rapid spread without overwhelming hospitals, however, has come into focus recently, as political pressure mounted to end COVID-related disruptions to daily life.
Gov. Kathy Hochul has repeatedly said she intends to lift many pandemic restrictions if a recent downward trend in cases and hospitalizations continued, though she hasn’t provided specific metrics or deadlines.
"We are continuing to turn the corner against the winter surge thanks to New Yorkers getting vaccinated, boosted and masking up," Hochul said in a statement Wednesday.
"But we can't let our guard down and undo all of the progress we've made,” she added.
Many of the current pandemic emergency measures, including an indoor mask mandate, will be reevaluated in early February.
The breakthrough case tally tracked infections among fully vaccinated New Yorkers, meaning they received at least two doses of Pfizer-BioNTech and Moderna vaccines, or one Johnson & Johnson dose.
But the number of New Yorkers who received a booster shot and then were infected remains unclear. That statistic is not tracked as part of the breakthrough case analysis, according to the state Department of Health website.
What New York says about COVID breakthroughs, reinfection
The latest tally of omicron-related breakthrough cases came as state health officials on Wednesday reported COVID-19 vaccines performed well against the delta variant.
But the state agency noted it was still too early to fully say how vaccines were performing against omicron.
In a study of COVID-19 cases from May 30 to Nov. 20, researchers in New York and California evaluated immunity from vaccines and from previous infection with the coronavirus that causes COVID-19.
Among the findings:
COVID-19 cases and hospitalization were substantially lower among people who had been vaccinated and/or survived a previous infection, compared to those unvaccinated and without a previous infection.
After delta took hold in late June and July, cases and hospitalizations were lowest among people with prior infection, especially those who were also vaccinated.
“This analysis represents another chapter in our ongoing studies of this virus and the most effective ways to be protected from illness,” senior study author Dr. Eli Rosenberg said in a statement.
The study also looked at how risks were highest among unvaccinated people without a previous COVID-19 diagnosis.
Among the findings:
The group was 4.5-fold more likely to have a positive COVID test than vaccinated people without a previous diagnosis.
It was 14.7-fold more likely to test positive than unvaccinated people with a previous diagnosis.
And it was 19.8-fold more likely to test positive than vaccinated people with a previous COVID-19 diagnosis.
In other words, people who were vaccinated after recovering from a prior infection had the best immunity.
“This study conducted by our premier scientists continues to underscore the importance of vaccination as a critical tool in the COVID-19 response,” state Health Commissioner Dr. Mary Bassett said in a statement.
New York on Wednesday also began releasing details of its analysis of COVID-19 reinfections among people who recovered from prior cases.
Among the findings through Jan. 16:
There have been 169,764 cases of reinfection.
This represents about 3.6% of all COVID infections reported to date in the state.
Of the total reinfections, 139,235, or 82%, have occurred since Dec. 13, 2021, which is connected to the omicron wave.
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This article originally appeared on New York State Team: How many vaccinated New Yorkers infected with COVID? Latest on omicron