A clinician draws a dose of the Moderna COVID-19 vaccine

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Philadelphia health officials released detailed data on breakthrough COVID cases Wednesday, along with the monthly count of hospitalizations and deaths among the city’s fully vaccinated population.

What it shows: Breakthrough cases and hospitalizations are rising, but vaccines remain highly effective in reducing the overall volume of serious infections in Philly.

About 1 in 5 new coronavirus cases in August were among fully vaccinated residents, according to the data. Fully vaccinated people also accounted for roughly 20% of the nearly 340 hospitalizations that month due to the virus, and 14% of deaths. However, as seen elsewhere across the country, vaccinated people still comprise a small fraction of COVID-related deaths.

Overall, Philadelphia saw only one-tenth the number of total deaths in August than it did than January.

Just 20 of the 498 people who died of coronavirus-related causes between April and August were fully vaccinated, with a range of 2 to 6 deaths per month. That figure squares with data that state officials released this week, showing that between January and August, just 3% of COVID deaths statewide occurred among vaccinated people.

“The overall number of hospitalization, vaccinations, and deaths have really dropped,” said acting Health Commissioner Cheryl Bettigole. “I believe our high vaccine rate is why our hospitals and ICUs are not overwhelmed like they are in other places.”

“Vaccine breakthroughs mean that a virus has broken through the protection a vaccine provides, in some way,” she added. “It’s important to note all vaccines have breakthrough cases. ”

The August uptick in cases and hospitalizations may be due to the vaccine’s diminishing effectiveness over time and the heightened transmissibility of the delta variant — or both, Garrow said on behalf of city epidemiologists.

The Philadelphia Department of Public Health has been analyzing the breakthrough data for weeks as it tries to combat new variants as well as widespread misinformation about vaccines.

Breakthrough cases are statistically expected to become more common as a greater proportion of the population becomes vaccinated, Garrow said. As of mid-September, more than 80% of Philadelphia’s adult population has gotten at least once dose of the COVID vaccine and 68% are fully vaccinated.

As vaccinations increased, the death toll plummeted. The city saw just 38 deaths total in August, compared to 354 in January of this year.

“Only 3.5% of people who’ve been sick enough to go to the hospital [this year] have been vaccinated,” Bettigole said. “These vaccines work. In every month, the vast majority of those testing positive, being hospitalized, and dying, weren’t vaccinated.”

City will follow White House guidance on boosters

Case counts among both vaccinated and unvaccinated residents dropped precipitously over the summer, but the uptick since August remains concerning, especially as the warm weather recedes and more people retreat indoors.

In January through March, when vaccines were scarce, the data shows fewer than 100 combined breakthrough cases — less than a third of a percentage point (0.3%) of the more than 35,000 infections recorded — but only a small fraction of the city’s population had received even one dose of the vaccine at that time.

In April, the numbers jumped a little: about 300 new cases were diagnosed in unvaccinated residents. That was still less than 2% of total cases that month.

And in August, for contrast, the breakthrough numbers grew over 1,600, accounting for more than 20% of cases that month, as well as the higher percentage of hospitalizations.

Health officials cautioned against reading too closely into August’s higher hospitalization rate among vaccinated people, as data contrasting ICU admissions and short duration stays was not readily available to help determine the severity of those cases, spokesperson James Garrow said.

One study suggests that hospitalization numbers nationwide may be inflated due to patients being admitted for other reasons while also showing signs of COVID.

Federal health officials are currently weighing evidence about the diminishing efficacy of vaccines over time as they build a plan to roll out booster shots — particularly among recipients of the Pfizer vaccine.

Israel began administering booster shots to residents 60 and older in July, and recently expanded the program to people over 30. Data on that program is expected to be released this week, according to Politico, and “shows that the Pfizer vaccine’s ability to prevent severe disease and hospitalization is waning over time.”

When it comes to booster shots, health officials say they will follow guidance from the Biden administration.

The White House had originally proposed a timeline to roll out booster shots for certain classes of people nationwide by the end of September, though regulators appear to be pumping the brakes on that plan. Some people have already begun taking it upon themselves to obtain their first booster shot before approval times, and local health officials warn residents against this.

Max Marin (he/him) was Billy Penn's investigative reporter from 2018 to 2021. A graduate of Temple University, he has produced award-winning journalism on local politics, criminal justice, immigration...