San Diego County residents have received about 119,000 fewer flu vaccinations this season than they did during the same span last year.
It’s a trend that worries Dr. Seema Shah, medical director of the county’s epidemiology and immunization branch, especially because weekly case totals show that this is shaping up to be a classic influenza season, one in which the bulk of illness will arrive in deepest winter.
“We should be doing much better than that, and the groups that are affected, interestingly, are (age) 60 to 69 and the 70- to 79-year-olds,” Shah said. “That’s unfortunate because all of the deaths are occurring in people over 65.”
Indeed, a tabulation of flu vaccination rates by age group shows that while every age group has seen a decrease, those in their 60s and 70s have thus far received 8 percent and 11.4 percent fewer vaccines year over year, far outpacing the average decrease of 3.3 percent.
And the picture is even worse for coronavirus. While 870,789 flu vaccines had been administered in San Diego County since July 1, only 369,895 were up-to-date with COVID-19 vaccination, according to the latest local respiratory virus report released Thursday by the county health department.
In recent weeks, monitoring shows that viral activity has increased on all fronts. There were 1,222 flu cases reported to the health department last week, nearly as many as the same week last year when influenza made an early appearance and three times greater than the prior five-year average.
Positive test results are less reliable for coronavirus, but local wastewater monitoring has documented significant increases in the estimated number of “copies” of the virus’s genetic material called RNA. On Nov. 15, 1.8 million copies per liter of wastewater were detected at San Diego’s Point Loma plant compared to 9.6 million on Dec. 13. At the Encina plant in North County, the spike is more pronounced, reaching 13 million copies, compared to just 1 million one month earlier. It’s a similarly shaped curve at a plant in South Bay, jumping from 445,804 copies on Dec. 3 to more than 3 million on Dec. 17.
Kristian Andersen, a virologist at Scripps Research, speculated on social media that these differences in volume from site to site could show waves of virus moving through the community. But he also noted that the northern and southern plants handle less overall volume of sewage than the Point Loma plant does.
“I think it more likely has to do with both Encina and South Bay being smaller sewer sheds and therefore more easily dominated by individuals who may be shedding a lot more virus,” Andersen said in an email.
While the researcher said the current spike in viral activity is likely driven by younger people, the holidays increase the probability of exposure of older generations. Those attending holiday parties, he said, would do well to test themselves and to stay home if they have symptoms. Air purifiers at parties and masks in public places, he added, can help lower exposure risk, though vaccination remains the most reliable method for reducing the severity of illness for those who get sick.
“While I don’t think hospitals will be overrun by cases, I do expect significant numbers as we move into the new year,” Andersen said. “Get the updated booster if you haven’t already (or it’s been 3+ months since having had COVID-19).
“This is especially important if you’re elderly or at risk, but my advice is for all age groups.”
Shaw urged unvaccinated residents not to feel that they have missed their window if they never got around to rolling up their sleeves this fall.
“We haven’t reached the peak of the flu or COVID yet, so this is still a great time to go out and get it,” Shah said.
