Researchers around the world have reported that Omicron is more transmissible than Delta, making breakthrough and repeat infections more likely.

The vaccine deployment in December 2020 signaled a turning point in the COVID-19 pandemic. By the end of May 2021, 40% of the U.S. population was fully vaccinated. But as vaccination rates lagged over the summer, new surges of COVID-19 came, including Delta in the summer of 2021, and now the Omicron variant, which comprises the majority of cases in the U.S.

The United States as of Jul. 20 reached over 1 million COVID-19-related deaths and 89.9 million COVID-19 cases, according to Johns Hopkins University. Currently, 67.1% of the population is fully vaccinated, and 48.1% of vaccinated people have received booster doses.

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Stacker compiled a list of the counties with highest COVID-19 infection rates in California using data from the U.S. Department of Health & Human Services and vaccination data from Covid Act Now. Counties are ranked by the highest infection rate per 100,000 residents within the week leading up to Jul. 19, 2022. Cumulative cases per 100,000 served as a tiebreaker.

Keep reading to see whether your county ranks among the highest COVID-19 infection rates in your state.

Doug Olson // Wikimedia Commons

#50. Placer County, CA

– New cases per 100k in the past week: 238 (948 new cases, +8% change from previous week)
– Cumulative cases per 100k: 20,042 (79,834 total cases)
— 24.0% less cases per 100k residents than California
– Cumulative deaths per 100k: 160 (637 total deaths)
— 31.3% less deaths per 100k residents than California
– Population that is fully vaccinated: 67.7% (269,781 fully vaccinated)

DimiTalen // Wikimedia Commons

#49. El Dorado County, CA

– New cases per 100k in the past week: 241 (465 new cases, +23% change from previous week)
– Cumulative cases per 100k: 17,813 (34,352 total cases)
— 32.5% less cases per 100k residents than California
– Cumulative deaths per 100k: 114 (219 total deaths)
— 51.1% less deaths per 100k residents than California
– Population that is fully vaccinated: 61.5% (118,680 fully vaccinated)

Kglavin // Wikimedia Commons

#48. Marin County, CA

– New cases per 100k in the past week: 246 (636 new cases, -9% change from previous week)
– Cumulative cases per 100k: 18,037 (46,685 total cases)
— 31.6% less cases per 100k residents than California
– Cumulative deaths per 100k: 116 (300 total deaths)
— 50.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 88.3% (228,512 fully vaccinated)

CFang // Wikimedia Commons

#47. Lake County, CA

– New cases per 100k in the past week: 250 (161 new cases, +50% change from previous week)
– Cumulative cases per 100k: 20,009 (12,883 total cases)
— 24.1% less cases per 100k residents than California
– Cumulative deaths per 100k: 219 (141 total deaths)
— 6.0% less deaths per 100k residents than California
– Population that is fully vaccinated: 55.6% (35,823 fully vaccinated)

CleanWater17 // Wikimedia Commons

#46. Colusa County, CA

– New cases per 100k in the past week: 260 (56 new cases, +133% change from previous week)
– Cumulative cases per 100k: 22,346 (4,815 total cases)
— 15.3% less cases per 100k residents than California
– Cumulative deaths per 100k: 102 (22 total deaths)
— 56.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 61.0% (13,135 fully vaccinated)

Doug Kerr // Wikicommons

#45. Shasta County, CA

– New cases per 100k in the past week: 262 (472 new cases, +29% change from previous week)
– Cumulative cases per 100k: 22,017 (39,648 total cases)
— 16.5% less cases per 100k residents than California
– Cumulative deaths per 100k: 319 (575 total deaths)
— 36.9% more deaths per 100k residents than California
– Population that is fully vaccinated: 47.0% (84,572 fully vaccinated)

Fred Hsu // Wikicommons

#44. Sonoma County, CA

– New cases per 100k in the past week: 281 (1,391 new cases, +19% change from previous week)
– Cumulative cases per 100k: 21,091 (104,262 total cases)
— 20.0% less cases per 100k residents than California
– Cumulative deaths per 100k: 101 (499 total deaths)
— 56.7% less deaths per 100k residents than California
– Population that is fully vaccinated: 79.4% (392,404 fully vaccinated)

Frank Schulenburg // Wikimedia Commons

#43. Nevada County, CA

– New cases per 100k in the past week: 284 (283 new cases, +43% change from previous week)
– Cumulative cases per 100k: 19,540 (19,492 total cases)
— 25.9% less cases per 100k residents than California
– Cumulative deaths per 100k: 131 (131 total deaths)
— 43.8% less deaths per 100k residents than California
– Population that is fully vaccinated: 64.0% (63,797 fully vaccinated)

Canva

#42. Butte County, CA

– New cases per 100k in the past week: 287 (629 new cases, +36% change from previous week)
– Cumulative cases per 100k: 20,336 (44,573 total cases)
— 22.9% less cases per 100k residents than California
– Cumulative deaths per 100k: 201 (440 total deaths)
— 13.7% less deaths per 100k residents than California
– Population that is fully vaccinated: 53.7% (117,761 fully vaccinated)

Stan Shebs // Wikicommons

#41. Napa County, CA

– New cases per 100k in the past week: 287 (395 new cases, +16% change from previous week)
– Cumulative cases per 100k: 22,875 (31,509 total cases)
— 13.3% less cases per 100k residents than California
– Cumulative deaths per 100k: 105 (145 total deaths)
— 54.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 79.8% (109,876 fully vaccinated)

Canva

#40. Sacramento County, CA

– New cases per 100k in the past week: 293 (4,540 new cases, +22% change from previous week)
– Cumulative cases per 100k: 22,872 (354,982 total cases)
— 13.3% less cases per 100k residents than California
– Cumulative deaths per 100k: 201 (3,119 total deaths)
— 13.7% less deaths per 100k residents than California
– Population that is fully vaccinated: 68.4% (1,062,039 fully vaccinated)

Epolk // Wikimedia Commons

#39. Yolo County, CA

– New cases per 100k in the past week: 294 (648 new cases, -55% change from previous week)
– Cumulative cases per 100k: 22,098 (48,725 total cases)
— 16.2% less cases per 100k residents than California
– Cumulative deaths per 100k: 147 (324 total deaths)
— 36.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 71.2% (157,001 fully vaccinated)

Frank Schulenburg // Wikimedia Commons

#38. Tehama County, CA

– New cases per 100k in the past week: 298 (194 new cases, +53% change from previous week)
– Cumulative cases per 100k: 24,161 (15,725 total cases)
— 8.4% less cases per 100k residents than California
– Cumulative deaths per 100k: 315 (205 total deaths)
— 35.2% more deaths per 100k residents than California
– Population that is fully vaccinated: 43.5% (28,301 fully vaccinated)

Ray Bouknight // Wikicommons

#37. Sutter County, CA

– New cases per 100k in the past week: 303 (294 new cases, +13% change from previous week)
– Cumulative cases per 100k: 25,631 (24,855 total cases)
— 2.8% less cases per 100k residents than California
– Cumulative deaths per 100k: 235 (228 total deaths)
— 0.9% more deaths per 100k residents than California
– Population that is fully vaccinated: 61.0% (59,149 fully vaccinated)

Bobak Ha’Eri // Wikimedia Commons

#36. Amador County, CA

– New cases per 100k in the past week: 307 (122 new cases, +20% change from previous week)
– Cumulative cases per 100k: 25,760 (10,240 total cases)
— 2.3% less cases per 100k residents than California
– Cumulative deaths per 100k: 219 (87 total deaths)
— 6.0% less deaths per 100k residents than California
– Population that is fully vaccinated: 53.4% (21,211 fully vaccinated)

Cory Maylett // Wikimedia Commons

#35. Humboldt County, CA

– New cases per 100k in the past week: 308 (417 new cases, +83% change from previous week)
– Cumulative cases per 100k: 17,810 (24,143 total cases)
— 32.5% less cases per 100k residents than California
– Cumulative deaths per 100k: 111 (150 total deaths)
— 52.4% less deaths per 100k residents than California
– Population that is fully vaccinated: 67.0% (90,779 fully vaccinated)

U.S. Army Corps of Engineers Sacramento District // Wikimedia Commons

#34. Yuba County, CA

– New cases per 100k in the past week: 311 (245 new cases, +25% change from previous week)
– Cumulative cases per 100k: 24,283 (19,103 total cases)
— 7.9% less cases per 100k residents than California
– Cumulative deaths per 100k: 158 (124 total deaths)
— 32.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 49.9% (39,238 fully vaccinated)

Binksternet // Wikimedia Commons

#33. Mendocino County, CA

– New cases per 100k in the past week: 314 (272 new cases, +24% change from previous week)
– Cumulative cases per 100k: 21,589 (18,728 total cases)
— 18.1% less cases per 100k residents than California
– Cumulative deaths per 100k: 151 (131 total deaths)
— 35.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 69.4% (60,239 fully vaccinated)

Pixabay

#32. Santa Barbara County, CA

– New cases per 100k in the past week: 323 (1,442 new cases, +25% change from previous week)
– Cumulative cases per 100k: 23,166 (103,436 total cases)
— 12.2% less cases per 100k residents than California
– Cumulative deaths per 100k: 157 (702 total deaths)
— 32.6% less deaths per 100k residents than California
– Population that is fully vaccinated: 70.0% (312,390 fully vaccinated)

LPS.1 // Wikicommons

#31. San Joaquin County, CA

– New cases per 100k in the past week: 327 (2,491 new cases, +36% change from previous week)
– Cumulative cases per 100k: 25,827 (196,840 total cases)
— 2.1% less cases per 100k residents than California
– Cumulative deaths per 100k: 297 (2,262 total deaths)
— 27.5% more deaths per 100k residents than California
– Population that is fully vaccinated: 62.7% (478,193 fully vaccinated)

Public Domain

#30. Stanislaus County, CA

– New cases per 100k in the past week: 330 (1,815 new cases, +36% change from previous week)
– Cumulative cases per 100k: 26,884 (148,038 total cases)
— 1.9% more cases per 100k residents than California
– Cumulative deaths per 100k: 307 (1,692 total deaths)
— 31.8% more deaths per 100k residents than California
– Population that is fully vaccinated: 57.8% (318,410 fully vaccinated)

Canva

#29. Solano County, CA

– New cases per 100k in the past week: 332 (1,488 new cases, +4% change from previous week)
– Cumulative cases per 100k: 23,249 (104,074 total cases)
— 11.8% less cases per 100k residents than California
– Cumulative deaths per 100k: 102 (457 total deaths)
— 56.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 68.2% (305,185 fully vaccinated)

Hollywood // Wikimedia Commons

#28. Orange County, CA

– New cases per 100k in the past week: 342 (10,851 new cases, +24% change from previous week)
– Cumulative cases per 100k: 21,212 (673,640 total cases)
— 19.6% less cases per 100k residents than California
– Cumulative deaths per 100k: 225 (7,161 total deaths)
— 3.4% less deaths per 100k residents than California
– Population that is fully vaccinated: 73.4% (2,332,105 fully vaccinated)

Canva

#27. Ventura County, CA

– New cases per 100k in the past week: 351 (2,966 new cases, +24% change from previous week)
– Cumulative cases per 100k: 24,440 (206,766 total cases)
— 7.3% less cases per 100k residents than California
– Cumulative deaths per 100k: 180 (1,519 total deaths)
— 22.7% less deaths per 100k residents than California
– Population that is fully vaccinated: 72.9% (616,584 fully vaccinated)

Mark Miller // Wikimedia Commons

#26. Merced County, CA

– New cases per 100k in the past week: 354 (982 new cases, +50% change from previous week)
– Cumulative cases per 100k: 27,922 (77,535 total cases)
— 5.9% more cases per 100k residents than California
– Cumulative deaths per 100k: 300 (833 total deaths)
— 28.8% more deaths per 100k residents than California
– Population that is fully vaccinated: 52.9% (146,959 fully vaccinated)

Naotake Murayama // Wikicommons

#25. Monterey County, CA

– New cases per 100k in the past week: 355 (1,541 new cases, +28% change from previous week)
– Cumulative cases per 100k: 24,490 (106,301 total cases)
— 7.1% less cases per 100k residents than California
– Cumulative deaths per 100k: 172 (747 total deaths)
— 26.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 73.8% (320,426 fully vaccinated)

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#24. San Francisco County, CA

– New cases per 100k in the past week: 358 (3,160 new cases, -5% change from previous week)
– Cumulative cases per 100k: 19,961 (175,963 total cases)
— 24.3% less cases per 100k residents than California
– Cumulative deaths per 100k: 105 (928 total deaths)
— 54.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 84.3% (743,047 fully vaccinated)

Craig Howell // Wikimedia Commons

#23. San Mateo County, CA

– New cases per 100k in the past week: 367 (2,813 new cases, +4% change from previous week)
– Cumulative cases per 100k: 21,508 (164,873 total cases)
— 18.4% less cases per 100k residents than California
– Cumulative deaths per 100k: 94 (723 total deaths)
— 59.7% less deaths per 100k residents than California
– Population that is fully vaccinated: 85.3% (653,985 fully vaccinated)

Jennifer Williams // Wikimedia Commons

#22. Alameda County, CA

– New cases per 100k in the past week: 371 (6,200 new cases, +16% change from previous week)
– Cumulative cases per 100k: 20,154 (336,842 total cases)
— 23.6% less cases per 100k residents than California
– Cumulative deaths per 100k: 114 (1,911 total deaths)
— 51.1% less deaths per 100k residents than California
– Population that is fully vaccinated: 82.5% (1,378,836 fully vaccinated)

Basar // Wikicommons

#21. San Luis Obispo County, CA

– New cases per 100k in the past week: 375 (1,061 new cases, +46% change from previous week)
– Cumulative cases per 100k: 23,172 (65,602 total cases)
— 12.1% less cases per 100k residents than California
– Cumulative deaths per 100k: 176 (499 total deaths)
— 24.5% less deaths per 100k residents than California
– Population that is fully vaccinated: 64.8% (183,545 fully vaccinated)

nickchapman // Wikicommons

#20. Kern County, CA

– New cases per 100k in the past week: 378 (3,401 new cases, +51% change from previous week)
– Cumulative cases per 100k: 28,828 (259,506 total cases)
— 9.3% more cases per 100k residents than California
– Cumulative deaths per 100k: 263 (2,364 total deaths)
— 12.9% more deaths per 100k residents than California
– Population that is fully vaccinated: 54.3% (488,535 fully vaccinated)

MARELBU // Wikimedia Commons

#19. Contra Costa County, CA

– New cases per 100k in the past week: 380 (4,384 new cases, +20% change from previous week)
– Cumulative cases per 100k: 21,373 (246,540 total cases)
— 19.0% less cases per 100k residents than California
– Cumulative deaths per 100k: 118 (1,356 total deaths)
— 49.4% less deaths per 100k residents than California
– Population that is fully vaccinated: 83.0% (957,652 fully vaccinated)

Uladzik Kryhin // Shutterstock

#18. Santa Clara County, CA

– New cases per 100k in the past week: 391 (7,531 new cases, +8% change from previous week)
– Cumulative cases per 100k: 21,411 (412,779 total cases)
— 18.8% less cases per 100k residents than California
– Cumulative deaths per 100k: 123 (2,371 total deaths)
— 47.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 86.3% (1,662,790 fully vaccinated)

Daniel Orth // Flickr

#17. Riverside County, CA

– New cases per 100k in the past week: 391 (9,670 new cases, +46% change from previous week)
– Cumulative cases per 100k: 27,503 (679,475 total cases)
— 4.3% more cases per 100k residents than California
– Cumulative deaths per 100k: 263 (6,508 total deaths)
— 12.9% more deaths per 100k residents than California
– Population that is fully vaccinated: 59.5% (1,469,982 fully vaccinated)

Kenneth Green // Wikimedia Commons

#16. Plumas County, CA

– New cases per 100k in the past week: 393 (74 new cases, +48% change from previous week)
– Cumulative cases per 100k: 20,317 (3,821 total cases)
— 23.0% less cases per 100k residents than California
– Cumulative deaths per 100k: 69 (13 total deaths)
— 70.4% less deaths per 100k residents than California
– Population that is fully vaccinated: 55.5% (10,446 fully vaccinated)

Almonroth // Wikimedia Commons

#15. Trinity County, CA

– New cases per 100k in the past week: 399 (49 new cases, +145% change from previous week)
– Cumulative cases per 100k: 13,252 (1,628 total cases)
— 49.8% less cases per 100k residents than California
– Cumulative deaths per 100k: 163 (20 total deaths)
— 30.0% less deaths per 100k residents than California
– Population that is fully vaccinated: 49.3% (6,052 fully vaccinated)

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#14. San Bernardino County, CA

– New cases per 100k in the past week: 403 (8,786 new cases, +38% change from previous week)
– Cumulative cases per 100k: 29,648 (646,358 total cases)
— 12.4% more cases per 100k residents than California
– Cumulative deaths per 100k: 363 (7,914 total deaths)
— 55.8% more deaths per 100k residents than California
– Population that is fully vaccinated: 57.6% (1,255,291 fully vaccinated)

EPoelzl // Wikimedia Commons

#13. Mariposa County, CA

– New cases per 100k in the past week: 413 (71 new cases, +103% change from previous week)
– Cumulative cases per 100k: 18,334 (3,154 total cases)
— 30.5% less cases per 100k residents than California
– Cumulative deaths per 100k: 174 (30 total deaths)
— 25.3% less deaths per 100k residents than California
– Population that is fully vaccinated: 46.5% (8,004 fully vaccinated)

David Jordan // Wikicommons

#12. Fresno County, CA

– New cases per 100k in the past week: 414 (4,135 new cases, +43% change from previous week)
– Cumulative cases per 100k: 28,153 (281,281 total cases)
— 6.7% more cases per 100k residents than California
– Cumulative deaths per 100k: 279 (2,790 total deaths)
— 19.7% more deaths per 100k residents than California
– Population that is fully vaccinated: 61.9% (618,520 fully vaccinated)

Public Domain

#11. Madera County, CA

– New cases per 100k in the past week: 416 (655 new cases, +42% change from previous week)
– Cumulative cases per 100k: 30,294 (47,661 total cases)
— 14.9% more cases per 100k residents than California
– Cumulative deaths per 100k: 236 (372 total deaths)
— 1.3% more deaths per 100k residents than California
– Population that is fully vaccinated: 55.2% (86,801 fully vaccinated)

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#10. Tulare County, CA

– New cases per 100k in the past week: 419 (1,952 new cases, +43% change from previous week)
– Cumulative cases per 100k: 31,550 (147,086 total cases)
— 19.6% more cases per 100k residents than California
– Cumulative deaths per 100k: 324 (1,510 total deaths)
— 39.1% more deaths per 100k residents than California
– Population that is fully vaccinated: 55.1% (257,076 fully vaccinated)

Chuck Abbe // Wikimedia Commons

#9. Inyo County, CA

– New cases per 100k in the past week: 427 (77 new cases, +12% change from previous week)
– Cumulative cases per 100k: 28,217 (5,090 total cases)
— 7.0% more cases per 100k residents than California
– Cumulative deaths per 100k: 310 (56 total deaths)
— 33.0% more deaths per 100k residents than California
– Population that is fully vaccinated: 63.7% (11,494 fully vaccinated)

Aaronbrick // Wikicommons

#8. Santa Cruz County, CA

– New cases per 100k in the past week: 433 (1,182 new cases, +52% change from previous week)
– Cumulative cases per 100k: 22,150 (60,516 total cases)
— 16.0% less cases per 100k residents than California
– Cumulative deaths per 100k: 98 (267 total deaths)
— 57.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 76.1% (207,897 fully vaccinated)

Michael Patrick // Wikimedia Commons

#7. San Benito County, CA

– New cases per 100k in the past week: 439 (276 new cases, +17% change from previous week)
– Cumulative cases per 100k: 24,912 (15,647 total cases)
— 5.5% less cases per 100k residents than California
– Cumulative deaths per 100k: 159 (100 total deaths)
— 31.8% less deaths per 100k residents than California
– Population that is fully vaccinated: 73.3% (46,027 fully vaccinated)

SD Dirk // Flickr

#6. San Diego County, CA

– New cases per 100k in the past week: 440 (14,698 new cases, +32% change from previous week)
– Cumulative cases per 100k: 27,598 (921,307 total cases)
— 4.6% more cases per 100k residents than California
– Cumulative deaths per 100k: 161 (5,370 total deaths)
— 30.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 75.3% (2,513,233 fully vaccinated)

BDS2006 // Wikimedia

#5. Los Angeles County, CA

– New cases per 100k in the past week: 450 (45,169 new cases, +26% change from previous week)
– Cumulative cases per 100k: 31,845 (3,196,987 total cases)
— 20.7% more cases per 100k residents than California
– Cumulative deaths per 100k: 321 (32,248 total deaths)
— 37.8% more deaths per 100k residents than California
– Population that is fully vaccinated: 74.1% (7,434,173 fully vaccinated)

Armona // Wikicommons

#4. Kings County, CA

– New cases per 100k in the past week: 488 (747 new cases, +54% change from previous week)
– Cumulative cases per 100k: 38,780 (59,310 total cases)
— 47.0% more cases per 100k residents than California
– Cumulative deaths per 100k: 294 (449 total deaths)
— 26.2% more deaths per 100k residents than California
– Population that is fully vaccinated: 45.8% (70,005 fully vaccinated)

Bobak Ha’Eri // Wikimedia Commons

#3. Tuolumne County, CA

– New cases per 100k in the past week: 622 (339 new cases, +95% change from previous week)
– Cumulative cases per 100k: 27,776 (15,132 total cases)
— 5.3% more cases per 100k residents than California
– Cumulative deaths per 100k: 360 (196 total deaths)
— 54.5% more deaths per 100k residents than California
– Population that is fully vaccinated: 53.2% (29,001 fully vaccinated)

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#2. Del Norte County, CA

– New cases per 100k in the past week: 759 (211 new cases, +33% change from previous week)
– Cumulative cases per 100k: 26,054 (7,246 total cases)
— 1.2% less cases per 100k residents than California
– Cumulative deaths per 100k: 194 (54 total deaths)
— 16.7% less deaths per 100k residents than California
– Population that is fully vaccinated: 48.5% (13,485 fully vaccinated)

Cbl62 // Wikicommons

#1. Imperial County, CA

– New cases per 100k in the past week: 816 (1,478 new cases, +21% change from previous week)
– Cumulative cases per 100k: 40,493 (73,379 total cases)
— 53.5% more cases per 100k residents than California
– Cumulative deaths per 100k: 521 (944 total deaths)
— 123.6% more deaths per 100k residents than California
– Population that is fully vaccinated: 95.0% (176,391 fully vaccinated)