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.

Researchers around the world have reported that Omicron is more transmissible than Delta, making breakthrough and repeat infections more likely. Early research suggests this strain may cause less severe illness than Delta and the original virus, however, health officials have warned an Omicron-driven surge could still increase hospitalization and death rates—especially in areas with less vaccinated populations.

The United States as of March 10 reached 964,448 COVID-19-related deaths and 79.4 million COVID-19 cases, according to Johns Hopkins University. Currently, 65.2% of the population is fully vaccinated, and 44.1% have received booster doses.

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 March 9, 2021. 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.

#50. Marin County, CA

– New cases per 100k in the past week: 56 (145 new cases, -45% change from previous week)
– Cumulative cases per 100k: 13,560 (35,097 total cases)
— 40.5% less cases per 100k residents than California
– Cumulative deaths per 100k: 105 (272 total deaths)
— 51.6% less deaths per 100k residents than California
– Population that is fully vaccinated: 86.7% (224,292 fully vaccinated)

#49. Modoc County, CA

– New cases per 100k in the past week: 57 (5 new cases, -77% change from previous week)
– Cumulative cases per 100k: 11,073 (979 total cases)
— 51.4% less cases per 100k residents than California
– Cumulative deaths per 100k: 79 (7 total deaths)
— 63.6% less deaths per 100k residents than California
– Population that is fully vaccinated: 41.5% (3,673 fully vaccinated)

#48. Alameda County, CA

– New cases per 100k in the past week: 57 (954 new cases, -79% change from previous week)
– Cumulative cases per 100k: 15,926 (266,180 total cases)
— 30.1% less cases per 100k residents than California
– Cumulative deaths per 100k: 106 (1,766 total deaths)
— 51.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 80.8% (1,349,877 fully vaccinated)

#47. Calaveras County, CA

– New cases per 100k in the past week: 59 (27 new cases, -54% change from previous week)
– Cumulative cases per 100k: 16,547 (7,596 total cases)
— 27.4% less cases per 100k residents than California
– Cumulative deaths per 100k: 253 (116 total deaths)
— 16.6% more deaths per 100k residents than California
– Population that is fully vaccinated: 52.7% (24,195 fully vaccinated)

#46. Santa Barbara County, CA

– New cases per 100k in the past week: 73 (328 new cases, -39% change from previous week)
– Cumulative cases per 100k: 20,187 (90,135 total cases)
— 11.4% less cases per 100k residents than California
– Cumulative deaths per 100k: 148 (659 total deaths)
— 31.8% less deaths per 100k residents than California
– Population that is fully vaccinated: 68.4% (305,237 fully vaccinated)

#45. San Benito County, CA

– New cases per 100k in the past week: 73 (46 new cases, -36% change from previous week)
– Cumulative cases per 100k: 21,258 (13,352 total cases)
— 6.7% less cases per 100k residents than California
– Cumulative deaths per 100k: 150 (94 total deaths)
— 30.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 71.3% (44,770 fully vaccinated)

#44. Placer County, CA

– New cases per 100k in the past week: 74 (293 new cases, -23% change from previous week)
– Cumulative cases per 100k: 17,446 (69,493 total cases)
— 23.4% less cases per 100k residents than California
– Cumulative deaths per 100k: 148 (591 total deaths)
— 31.8% less deaths per 100k residents than California
– Population that is fully vaccinated: 66.4% (264,339 fully vaccinated)

#43. Sacramento County, CA

– New cases per 100k in the past week: 76 (1,187 new cases, -38% change from previous week)
– Cumulative cases per 100k: 19,379 (300,773 total cases)
— 14.9% less cases per 100k residents than California
– Cumulative deaths per 100k: 185 (2,869 total deaths)
— 14.7% less deaths per 100k residents than California
– Population that is fully vaccinated: 66.6% (1,034,337 fully vaccinated)

#42. Tehama County, CA

– New cases per 100k in the past week: 77 (50 new cases, -46% change from previous week)
– Cumulative cases per 100k: 22,353 (14,548 total cases)
— 1.9% less cases per 100k residents than California
– Cumulative deaths per 100k: 243 (158 total deaths)
— 12.0% more deaths per 100k residents than California
– Population that is fully vaccinated: 42.5% (27,637 fully vaccinated)

#41. San Joaquin County, CA

– New cases per 100k in the past week: 78 (593 new cases, -35% change from previous week)
– Cumulative cases per 100k: 22,879 (174,375 total cases)
— 0.4% more cases per 100k residents than California
– Cumulative deaths per 100k: 274 (2,091 total deaths)
— 26.3% more deaths per 100k residents than California
– Population that is fully vaccinated: 60.2% (459,064 fully vaccinated)

#40. Riverside County, CA

– New cases per 100k in the past week: 78 (1,915 new cases, -31% change from previous week)
– Cumulative cases per 100k: 24,911 (615,445 total cases)
— 9.3% more cases per 100k residents than California
– Cumulative deaths per 100k: 254 (6,279 total deaths)
— 17.1% more deaths per 100k residents than California
– Population that is fully vaccinated: 57.7% (1,424,607 fully vaccinated)

#39. Contra Costa County, CA

– New cases per 100k in the past week: 81 (938 new cases, -48% change from previous week)
– Cumulative cases per 100k: 17,249 (198,967 total cases)
— 24.3% less cases per 100k residents than California
– Cumulative deaths per 100k: 109 (1,256 total deaths)
— 49.8% less deaths per 100k residents than California
– Population that is fully vaccinated: 81.5% (940,024 fully vaccinated)

#38. Solano County, CA

– New cases per 100k in the past week: 81 (362 new cases, -58% change from previous week)
– Cumulative cases per 100k: 19,282 (86,313 total cases)
— 15.4% less cases per 100k residents than California
– Cumulative deaths per 100k: 97 (435 total deaths)
— 55.3% less deaths per 100k residents than California
– Population that is fully vaccinated: 66.0% (295,549 fully vaccinated)

#37. Santa Clara County, CA

– New cases per 100k in the past week: 83 (1,600 new cases, -28% change from previous week)
– Cumulative cases per 100k: 16,636 (320,714 total cases)
— 27.0% less cases per 100k residents than California
– Cumulative deaths per 100k: 114 (2,202 total deaths)
— 47.5% less deaths per 100k residents than California
– Population that is fully vaccinated: 84.9% (1,635,937 fully vaccinated)

#36. San Bernardino County, CA

– New cases per 100k in the past week: 91 (1,984 new cases, -8% change from previous week)
– Cumulative cases per 100k: 26,707 (582,245 total cases)
— 17.2% more cases per 100k residents than California
– Cumulative deaths per 100k: 307 (6,703 total deaths)
— 41.5% more deaths per 100k residents than California
– Population that is fully vaccinated: 56.0% (1,221,724 fully vaccinated)

#35. Humboldt County, CA

– New cases per 100k in the past week: 94 (127 new cases, -50% change from previous week)
– Cumulative cases per 100k: 14,559 (19,736 total cases)
— 36.1% less cases per 100k residents than California
– Cumulative deaths per 100k: 101 (137 total deaths)
— 53.5% less deaths per 100k residents than California
– Population that is fully vaccinated: 65.4% (88,613 fully vaccinated)

#34. Shasta County, CA

– New cases per 100k in the past week: 95 (171 new cases, -44% change from previous week)
– Cumulative cases per 100k: 20,256 (36,477 total cases)
— 11.1% less cases per 100k residents than California
– Cumulative deaths per 100k: 274 (493 total deaths)
— 26.3% more deaths per 100k residents than California
– Population that is fully vaccinated: 46.0% (82,779 fully vaccinated)

#33. Glenn County, CA

– New cases per 100k in the past week: 95 (27 new cases, -37% change from previous week)
– Cumulative cases per 100k: 22,808 (6,476 total cases)
— 0.1% more cases per 100k residents than California
– Cumulative deaths per 100k: 151 (43 total deaths)
— 30.4% less deaths per 100k residents than California
– Population that is fully vaccinated: 54.4% (15,442 fully vaccinated)

#32. Mariposa County, CA

– New cases per 100k in the past week: 99 (17 new cases, -51% change from previous week)
– Cumulative cases per 100k: 14,910 (2,565 total cases)
— 34.6% less cases per 100k residents than California
– Cumulative deaths per 100k: 35 (6 total deaths)
— 83.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 43.9% (7,551 fully vaccinated)

#31. Los Angeles County, CA

– New cases per 100k in the past week: 99 (9,907 new cases, 0% change from previous week)
– Cumulative cases per 100k: 27,863 (2,797,184 total cases)
— 22.3% more cases per 100k residents than California
– Cumulative deaths per 100k: 306 (30,759 total deaths)
— 41.0% more deaths per 100k residents than California
– Population that is fully vaccinated: 72.3% (7,262,335 fully vaccinated)

#30. Siskiyou County, CA

– New cases per 100k in the past week: 101 (44 new cases, -51% change from previous week)
– Cumulative cases per 100k: 16,346 (7,117 total cases)
— 28.3% less cases per 100k residents than California
– Cumulative deaths per 100k: 170 (74 total deaths)
— 21.7% less deaths per 100k residents than California
– Population that is fully vaccinated: 47.9% (20,863 fully vaccinated)

#29. San Mateo County, CA

– New cases per 100k in the past week: 103 (790 new cases, -27% change from previous week)
– Cumulative cases per 100k: 16,431 (125,957 total cases)
— 27.9% less cases per 100k residents than California
– Cumulative deaths per 100k: 82 (630 total deaths)
— 62.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 83.7% (641,460 fully vaccinated)

#28. Yolo County, CA

– New cases per 100k in the past week: 103 (227 new cases, -18% change from previous week)
– Cumulative cases per 100k: 17,707 (39,043 total cases)
— 22.3% less cases per 100k residents than California
– Cumulative deaths per 100k: 139 (306 total deaths)
— 35.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 69.6% (153,488 fully vaccinated)

#27. Butte County, CA

– New cases per 100k in the past week: 103 (225 new cases, -13% change from previous week)
– Cumulative cases per 100k: 17,935 (39,310 total cases)
— 21.3% less cases per 100k residents than California
– Cumulative deaths per 100k: 172 (378 total deaths)
— 20.7% less deaths per 100k residents than California
– Population that is fully vaccinated: 52.7% (115,417 fully vaccinated)

#26. Monterey County, CA

– New cases per 100k in the past week: 103 (445 new cases, -41% change from previous week)
– Cumulative cases per 100k: 21,007 (91,184 total cases)
— 7.8% less cases per 100k residents than California
– Cumulative deaths per 100k: 163 (706 total deaths)
— 24.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 71.5% (310,186 fully vaccinated)

#25. Trinity County, CA

– New cases per 100k in the past week: 106 (13 new cases, -52% change from previous week)
– Cumulative cases per 100k: 11,925 (1,465 total cases)
— 47.7% less cases per 100k residents than California
– Cumulative deaths per 100k: 163 (20 total deaths)
— 24.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 48.4% (5,943 fully vaccinated)

#24. Merced County, CA

– New cases per 100k in the past week: 106 (294 new cases, -41% change from previous week)
– Cumulative cases per 100k: 25,243 (70,095 total cases)
— 10.8% more cases per 100k residents than California
– Cumulative deaths per 100k: 285 (791 total deaths)
— 31.3% more deaths per 100k residents than California
– Population that is fully vaccinated: 50.6% (140,570 fully vaccinated)

#23. Yuba County, CA

– New cases per 100k in the past week: 108 (85 new cases, -17% change from previous week)
– Cumulative cases per 100k: 21,452 (16,876 total cases)
— 5.8% less cases per 100k residents than California
– Cumulative deaths per 100k: 146 (115 total deaths)
— 32.7% less deaths per 100k residents than California
– Population that is fully vaccinated: 48.3% (37,966 fully vaccinated)

#22. San Luis Obispo County, CA

– New cases per 100k in the past week: 120 (340 new cases, -20% change from previous week)
– Cumulative cases per 100k: 19,618 (55,541 total cases)
— 13.9% less cases per 100k residents than California
– Cumulative deaths per 100k: 158 (448 total deaths)
— 27.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 63.5% (179,665 fully vaccinated)

#21. Colusa County, CA

– New cases per 100k in the past week: 121 (26 new cases, -13% change from previous week)
– Cumulative cases per 100k: 20,940 (4,512 total cases)
— 8.1% less cases per 100k residents than California
– Cumulative deaths per 100k: 97 (21 total deaths)
— 55.3% less deaths per 100k residents than California
– Population that is fully vaccinated: 59.7% (12,870 fully vaccinated)

#20. Madera County, CA

– New cases per 100k in the past week: 122 (192 new cases, -43% change from previous week)
– Cumulative cases per 100k: 27,420 (43,139 total cases)
— 20.4% more cases per 100k residents than California
– Cumulative deaths per 100k: 225 (354 total deaths)
— 3.7% more deaths per 100k residents than California
– Population that is fully vaccinated: 53.5% (84,126 fully vaccinated)

#19. Sonoma County, CA

– New cases per 100k in the past week: 125 (616 new cases, -15% change from previous week)
– Cumulative cases per 100k: 17,113 (84,597 total cases)
— 24.9% less cases per 100k residents than California
– Cumulative deaths per 100k: 96 (473 total deaths)
— 55.8% less deaths per 100k residents than California
– Population that is fully vaccinated: 77.6% (383,487 fully vaccinated)

#18. Plumas County, CA

– New cases per 100k in the past week: 138 (26 new cases, -33% change from previous week)
– Cumulative cases per 100k: 16,244 (3,055 total cases)
— 28.7% less cases per 100k residents than California
– Cumulative deaths per 100k: 69 (13 total deaths)
— 68.2% less deaths per 100k residents than California
– Population that is fully vaccinated: 54.4% (10,236 fully vaccinated)

#17. Napa County, CA

– New cases per 100k in the past week: 140 (193 new cases, -8% change from previous week)
– Cumulative cases per 100k: 19,210 (26,460 total cases)
— 15.7% less cases per 100k residents than California
– Cumulative deaths per 100k: 99 (136 total deaths)
— 54.4% less deaths per 100k residents than California
– Population that is fully vaccinated: 78.2% (107,734 fully vaccinated)

#16. Santa Cruz County, CA

– New cases per 100k in the past week: 143 (390 new cases, -30% change from previous week)
– Cumulative cases per 100k: 17,828 (48,708 total cases)
— 21.7% less cases per 100k residents than California
– Cumulative deaths per 100k: 93 (254 total deaths)
— 57.1% less deaths per 100k residents than California
– Population that is fully vaccinated: 74.5% (203,411 fully vaccinated)

#15. Inyo County, CA

– New cases per 100k in the past week: 144 (26 new cases, -13% change from previous week)
– Cumulative cases per 100k: 25,101 (4,528 total cases)
— 10.2% more cases per 100k residents than California
– Cumulative deaths per 100k: 310 (56 total deaths)
— 42.9% more deaths per 100k residents than California
– Population that is fully vaccinated: 61.5% (11,086 fully vaccinated)

#14. Imperial County, CA

– New cases per 100k in the past week: 147 (267 new cases, -51% change from previous week)
– Cumulative cases per 100k: 36,231 (65,656 total cases)
— 59.0% more cases per 100k residents than California
– Cumulative deaths per 100k: 491 (890 total deaths)
— 126.3% more deaths per 100k residents than California
– Population that is fully vaccinated: 91.2% (165,195 fully vaccinated)

#13. Fresno County, CA

– New cases per 100k in the past week: 149 (1,488 new cases, -25% change from previous week)
– Cumulative cases per 100k: 24,982 (249,597 total cases)
— 9.7% more cases per 100k residents than California
– Cumulative deaths per 100k: 266 (2,653 total deaths)
— 22.6% more deaths per 100k residents than California
– Population that is fully vaccinated: 60.2% (601,348 fully vaccinated)

#12. Lake County, CA

– New cases per 100k in the past week: 151 (97 new cases, -32% change from previous week)
– Cumulative cases per 100k: 17,748 (11,427 total cases)
— 22.1% less cases per 100k residents than California
– Cumulative deaths per 100k: 202 (130 total deaths)
— 6.9% less deaths per 100k residents than California
– Population that is fully vaccinated: 54.2% (34,879 fully vaccinated)

#11. Stanislaus County, CA

– New cases per 100k in the past week: 153 (844 new cases, -18% change from previous week)
– Cumulative cases per 100k: 24,416 (134,449 total cases)
— 7.2% more cases per 100k residents than California
– Cumulative deaths per 100k: 279 (1,537 total deaths)
— 28.6% more deaths per 100k residents than California
– Population that is fully vaccinated: 56.1% (308,738 fully vaccinated)

#10. San Diego County, CA

– New cases per 100k in the past week: 159 (5,292 new cases, -14% change from previous week)
– Cumulative cases per 100k: 23,705 (791,352 total cases)
— 4.0% more cases per 100k residents than California
– Cumulative deaths per 100k: 152 (5,068 total deaths)
— 30.0% less deaths per 100k residents than California
– Population that is fully vaccinated: 74.7% (2,492,721 fully vaccinated)

#9. Tulare County, CA

– New cases per 100k in the past week: 159 (739 new cases, -34% change from previous week)
– Cumulative cases per 100k: 28,280 (131,841 total cases)
— 24.1% more cases per 100k residents than California
– Cumulative deaths per 100k: 282 (1,316 total deaths)
— 30.0% more deaths per 100k residents than California
– Population that is fully vaccinated: 53.5% (249,188 fully vaccinated)

#8. Amador County, CA

– New cases per 100k in the past week: 166 (66 new cases, -8% change from previous week)
– Cumulative cases per 100k: 22,696 (9,022 total cases)
— 0.4% less cases per 100k residents than California
– Cumulative deaths per 100k: 211 (84 total deaths)
— 2.8% less deaths per 100k residents than California
– Population that is fully vaccinated: 52.0% (20,666 fully vaccinated)

#7. Sutter County, CA

– New cases per 100k in the past week: 193 (187 new cases, +10% change from previous week)
– Cumulative cases per 100k: 22,997 (22,300 total cases)
— 0.9% more cases per 100k residents than California
– Cumulative deaths per 100k: 224 (217 total deaths)
— 3.2% more deaths per 100k residents than California
– Population that is fully vaccinated: 59.6% (57,821 fully vaccinated)

#6. Mendocino County, CA

– New cases per 100k in the past week: 203 (176 new cases, -16% change from previous week)
– Cumulative cases per 100k: 18,275 (15,853 total cases)
— 19.8% less cases per 100k residents than California
– Cumulative deaths per 100k: 135 (117 total deaths)
— 37.8% less deaths per 100k residents than California
– Population that is fully vaccinated: 67.9% (58,942 fully vaccinated)

#5. Del Norte County, CA

– New cases per 100k in the past week: 241 (67 new cases, -40% change from previous week)
– Cumulative cases per 100k: 21,376 (5,945 total cases)
— 6.2% less cases per 100k residents than California
– Cumulative deaths per 100k: 173 (48 total deaths)
— 20.3% less deaths per 100k residents than California
– Population that is fully vaccinated: 46.8% (13,028 fully vaccinated)

#4. Kings County, CA

– New cases per 100k in the past week: 299 (458 new cases, -30% change from previous week)
– Cumulative cases per 100k: 35,728 (54,643 total cases)
— 56.8% more cases per 100k residents than California
– Cumulative deaths per 100k: 283 (433 total deaths)
— 30.4% more deaths per 100k residents than California
– Population that is fully vaccinated: 44.3% (67,746 fully vaccinated)

#3. Tuolumne County, CA

– New cases per 100k in the past week: 303 (165 new cases, +11% change from previous week)
– Cumulative cases per 100k: 23,811 (12,972 total cases)
— 4.5% more cases per 100k residents than California
– Cumulative deaths per 100k: 329 (179 total deaths)
— 51.6% more deaths per 100k residents than California
– Population that is fully vaccinated: 51.7% (28,150 fully vaccinated)

#2. Kern County, CA

– New cases per 100k in the past week: 343 (3,087 new cases, -11% change from previous week)
– Cumulative cases per 100k: 26,101 (234,963 total cases)
— 14.6% more cases per 100k residents than California
– Cumulative deaths per 100k: 239 (2,152 total deaths)
— 10.1% more deaths per 100k residents than California
– Population that is fully vaccinated: 52.7% (474,630 fully vaccinated)

#1. Lassen County, CA

– New cases per 100k in the past week: 363 (111 new cases, +14% change from previous week)
– Cumulative cases per 100k: 32,038 (9,795 total cases)
— 40.6% more cases per 100k residents than California
– Cumulative deaths per 100k: 203 (62 total deaths)
— 6.5% less deaths per 100k residents than California
– Population that is fully vaccinated: 28.6% (8,730 fully vaccinated)