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New data from the Centers for Disease Control and Prevention show just how hard the COVID-19 Delta variant hit unvaccinated Americans. The infection rate for unvaccinated people was more than six times higher than for vaccinated people.

The peak of Delta’s impact was in mid-September with a seven-day average of 170,590 new cases. Cases dropped to 70,409 by the end of October.

The Delta variant surge peaked in mid-September.

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Between June 30 and October 31 — the approximate span for the latest Delta variant surge —cases increased in every state and among every age group.

During the Delta surge, the weekly infection rate for unvaccinated people was six to seven times higher than that of vaccinated people.

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The unvaccinated infection rate hit its Delta surge peak the week ending August 21, when737 out of 100,000 unvaccinated people contracted COVID-19. The vaccinated infection rate that week was 121 new cases per 100,000 vaccinated people.

Some vaccines were more effective at preventing infections than others. People who received the two-dose Moderna vaccine had the lowest infection rate among vaccinated people at 86 cases per 100,000 people. The highest rate was among those who got the single-shot Johnson & Johnson vaccine: 172 cases per 100,000 people.

The data is from 14 states and two other jurisdictions that account for 30% of the US population.[1]

Across age groups, unvaccinated people had a higher rate of infection than vaccinated people.

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The gap in infection rates for the vaccinated and unvaccinated was most pronounced for those between ages 12 to 17. During the week ending August 28, the weekly case rate among the unvaccinated in this group was 887 per 100,000 people compared with 85 cases per 100,000 vaccinated teenagers.

Between June 30 and October 31, 95.5 million vaccine doses were administered. During that time, the share of the population receiving at least one dose increased from 54% to 67%, and the percentage of people fully vaccinated rose from 47% to 58%. Four percent of Americans received an additional dose or a booster shot of a vaccine as of October 31.

The share of Americans getting additional doses or booster shots is growing at an increasingly faster rate.

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Mississippi, Florida, and Louisiana had the highest combined case rate for the first two months of the surge. Vaccinations subsequently rose with more than 16% of people in these three states receiving at least one vaccine dose since the end of June. These three states had the biggest increases in vaccinated populations after cases rose sharply due to Delta.

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Alaska had the highest caseload during the four-month Delta surge, with 8% of its population infected with COVID-19. Maryland and Connecticut had the lightest virus caseloads, with just over 1% of their populations contracting COVID-19.

The Delta variant also shifted which states were hit hardest by COVID-19 deaths.

Before July, New Jersey was the worst-hit state for cumulative COVID-19 death rates, with 297 deaths per 100,000 people. But the Delta surge drove cumulative death rates in Mississippi, Alabama, and Louisiana over 300 per 100,000 residents. During the same period, New Jersey had the nation’s lowest COVID-19 death rate, with two deaths per 100,000 residents.

Three southern states overtook New Jersey with higher death rates over the pandemic.

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For more on COVID-19, visit the cases and deaths map and the vaccine tracker.

Aggregation of state and local sources
COVID-19 Vaccinations in the United States,Jurisdiction
Rates of COVID-19 Cases or Deaths by Age Group and Vaccination Status
[1]

Alabama, Arizona, Arkansas, Colorado, Florida, Georgia, Idaho, Louisiana, Massachusetts, Michigan, Nebraska, New Mexico, Utah, and Wisconsin — as well as New York City and King County, Washington.

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