‘Breakthrough’ COVID-19 cases are one in five new infections

Number of infections among the fully vaccinated in NJ has risen but remains the same proportion of total cases
Credit: (AP Photo/Mary Altaffer)
A vaccine dose about to be administered

While there are a growing number of COVID-19 breakthrough cases in New Jersey, state data shows they remain fewer than one in five of all new diagnoses as more people become infected each week due to the highly transmissible delta variant.

Gov. Phil Murphy on Monday shared new details on breakthrough cases — or fully immunized individuals who are nevertheless diagnosed with COVID-19 — for the week of Aug. 2 to 8. The 1,397 breakthrough cases identified that week represent about 18.4% of 7,611 positive diagnoses recorded in that seven-day period. While the overall numbers are higher, that percentage is slightly lower than the rate of breakthrough cases seen during the week of July 20 to 26, state data show.

“As the delta variant continues its rampage, we are seeing an increase in the number of breakthrough cases. However, the percentage of positive test results from fully vaccinated individuals continues to be only a small part of the overall,” Murphy said at his pandemic briefing Monday. The overall breakthrough rate was one in 500 vaccinated individuals as of Aug. 8, he said, or 0.2%.

Nearly 5.5 million New Jerseyans are now fully vaccinated against COVID-19 — with thousands more getting shots every day — but the percentage of breakthrough cases had been on the rise since earlier this summer. An NJ Spotlight News analysis of state data found that breakthrough cases grew by more than 16% between June 29 and July 12 while hospitalizations jumped by two-thirds and the number of deaths rose by more than 50%.

On Monday Murphy said there were 25 COVID-19-related hospitalizations involving vaccinated individuals during the week of Aug. 2 to 8, or 1.8% of COVID-19 admissions during that period. Since mid-January some 270 vaccinated people have been hospitalized with COVID-19, he said — or only about 4% of those who sought acute-care treatment for the virus over those months.

No fully vaccinated New Jerseyans died of COVID-19 during the first full week of August, Murphy noted, but there have been 58 fatalities since mid-January involving immunized individuals. That amounts to less than 0.6% of all deaths, he said, making the vaccines more than 99% effective against mortality.

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