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Volume 32, Supplement –Summer 2026
SUPPLEMENT ISSUE
Supplement
Correlations between Wastewater Concentrations of Influenza A and Respiratory Syncytial Viruses and Clinical Laboratory Testing and Hospitalization Data, California, USA
Table 1
Descriptive characteristics for each county and sewershed included in a study of correlations between wastewater concentrations of influenza A and respiratory syncytial viruses and clinical laboratory testing and hospitalization data, California, USA*
| County | County-level |
Sewershed-level |
|||||||
|---|---|---|---|---|---|---|---|---|---|
| Population | No. influenza hospitalizations | Sentinel laboratory, no. positive specimens |
Sewershed | Estimated population | No. ELR influenza A virus–positive specimens | No. wastewater samples processed | |||
| Influenza A | RSV | ||||||||
| Alameda |
1,658,061 |
991 |
7,184 |
5,999 |
East Bay |
740,000 |
4,057 |
261 |
|
| Contra Costa | 1,158,249 | 852 | 6,686 | 5,167 | Central Contra Costa | 484,800 | 3,460 | 223 | |
| Richmond |
100,000 |
1,215 |
207 |
||||||
| Marin |
254,743 |
144 |
703 |
1,544 |
Novato |
53,000 |
618 |
241 |
|
| Sacramento |
1,596,281 |
1,657 |
6,692 |
5,092 |
Sacramento |
1,480,000 |
16,362 |
548 |
|
| San Francisco | 845,355 | 574 | 2,706 | 2,847 | Oceanside | 250,000 | 1,133 | 524 | |
| Southeast† |
750,000 |
3,607 |
541 |
||||||
| San Mateo | 747,777 | 293 | 3,503 | 2,043 | Half Moon Bay | 28,000 | 151 | 224 | |
| San Mateo | 150,000 | 1,149 | 232 | ||||||
| Silicon Valley |
199,000 |
1,900 |
546 |
||||||
| Santa Clara | 1,921,406 | 3,066 | 11,336 | 8,278 | Gilroy/Morgan Hill | 110,338 | 1,631 | 550 | |
| Palo Alto† | 236,000 | 1,225 | 549 | ||||||
| San Jose | 1,500,000 | 12,746 | 550 | ||||||
| Sunnyvale |
153,000 |
998 |
536 |
||||||
| Santa Cruz | 263,454 | NA‡ | 113 | NA‡ | Santa Cruz City | 70,000 | 272 | 238 | |
| Santa Cruz County |
94,000 |
350 |
239 |
||||||
| Sonoma |
482,050 |
448 |
2,938 |
1,957 |
Petaluma |
65,000 |
641 |
163 |
|
| Yolo |
224,088 |
NA‡ |
115 |
165 |
Davis |
70,717 |
332 |
343 |
|
| Total | 9,151,464 | 8,025 | 41,976 | 33,173 | Total | 6,689,855 | 51,847 | 6,715 | |
*ELR, electronic laboratory reporting; NA, not applicable; RSV, respiratory syncytial virus. †The San Francisco Southeast sewershed and the Palo Alto sewershed both encompass small portions of neighboring San Mateo County. As a result, the total population coverage for the 2 San Francisco sewersheds is larger than the San Francisco County population, and the total population coverage for the 4 Santa Clara sewersheds is larger than the Santa Clara County population. ‡Numbers insufficient for inclusion in the analysis.