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Cook County Vaccine Sign-up Got 500K Hits Per Second During Appointment Drop, Crashing Website for Some

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The Cook County COVID vaccine registration website saw roughly half a million hits per second during the latest appointment drop on Wednesday, causing the site to crash for some users as demand for the vaccine continues to dwarf available supply.

Cook County released about 16,000 first-dose COVID vaccine appointments at 12 p.m. on Wednesday for five suburban vaccination sites in Des Plaines, Forest Park, River Grove, South Holland and Riverside.

Cook County Health's Chief Communications Officer Caryn Stancik said Thursday that the website saw 500,000 requests per second for those appointments during the drop. That spike caused technical problems for many users, some of whom complained on social media that the registration had crashed entirely. All of the appointments were booked in about two hours, Stancik said.

Earlier this week, Cook County made two major expansions of its vaccine rollout: moving into Phase 1B Plus, opening eligibility to residents with certain underlying health conditions, and opening its mass vaccination sites - previously limited only to residents of the county - to all Illinoisans.

For a complete look at who is eligible to receive the COVID vaccine and when in Illinois, click here.

Those two changes sparked a surge in demand for appointments through Cook County. Last week, the county's site had between 700,000 and 800,000 people registered on the list of people seeking appointments, Stancik said. By Wednesday morning, that number grew to 1.3 million people.

Stancik said that the county's scheduling platform, a third-party vendor used in the health care field, made some adjustments to the site in anticipation of the heightened demand - but the website performance still slowed under the massive spike in traffic.

"In preparation for yesterday’s COVID appointment release, Cook County Health's partner in COVID vaccine scheduling -- Luma Health – made architecture changes that resulted in degraded performance while booking appointments," Stancik said. "During the release, Luma Health serviced significantly higher volumes than in previous releases, reaching over 500,000 requests per second which triggered rate limiters in Luma Health's underlying platforms. We apologize for the inconvenience and expect this issue to be corrected."

“We understand the inconvenience this has caused," Luma Health’s Chief Technology Officer Aditya Bansod said in a statement to Cook County Health. "We have under anticipated the load of the expansion to the larger patient populations and we apologize for the difficulty and challenge this created while trying to schedule a vaccine appointment."

Complaints flooded social media after users were unable to access the appointments, some saying they struggled for more than an hour as the website repeatedly crashed, others calling the sign-up process "atrocious," "needlessly complicated" and "a complete waste of time," among other complaints.

"The issue with the 16,000 doses is it sounds like a lot, but the problem is Cook County opened to the entire state last week," said Caryn Davidson, who volunteers her time to help people in need of vaccinations book appointments.

"It's so much harder now than it was a couple weeks ago," added another volunteer Sarah Summers.

The county's website is far from the only registration portal that has been plagued by technical issues frustrating users. Walgreens has apologized on multiple occasions for glitches that caused what they called "delays or failures," in their online registration process, as well as an issue last week in which users were able to book only second-dose appointments without first doses.

Chicago officials also said this week that they "continue having to swat down rumors" about the United Center's mass vaccination site, the launch of which was marked by confusion after officials narrowed eligibility criteria less than an hour before opening appointments.

Currently, the United Center, the city of Chicago and much of the rest of the state of Illinois are all operating under different eligibility guidelines. After following its own timeline for nearly a month, Cook County moved into the same Phase 1B Plus as the rest of the state this week. But the criteria differing by jurisdiction at different times has presented an added challenge to some wondering if they qualify to receive their shots, even before they begin to search for appointments.

On Wednesday, the official Twitter account for the Cook County government responded to some of those complaining about its site by saying in part, "Apologies for the website woes."

Cook County operates five total mass vaccination sites in the suburbs. They are:

  • The Tinley Park Convention Center, 18451 Convention Center Drive
  • South Suburban College, 15800 State St. in South Holland
  • Triton College, 2000 5th Ave. in River Grove
  • A former K-Mart at 1155 E Oakton St in Des Plaines
  • Former HOBO at 7600 West Roosevelt Road in Forest Park

The county has yet to announce the time and date of its next drop, but any appointments at those mass vaccination sites can be booked on the Cook County vaccine website or by calling the county's hotline at (833) 308-1988 on weekdays from 7 a.m. to 7 p.m.

Gov. J.B. Pritzker last week announced that all Illinois residents age 16 and older outside the city of Chicago will become eligible for the COVID-19 vaccine next month. The following day, he announced that more essential workers like restaurant workers, higher education staff and more would become eligible ahead of that expansion.

For a complete look at how to make a COVID vaccine appointment in Illinois, click here.

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