In-Depth: South Bay COVID cases climb despite high vaccination rates

San Ysidro, Otay Mesa have highest case rates in county
Posted at 6:01 AM, Dec 03, 2021
and last updated 2021-12-03 11:46:21-05

SAN YSIDRO, Calif. (KGTV) - New numbers from San Diego County show COVID cases in the South Bay are still the highest in the region, even though two Zip codes along the border have some of the highest vaccination numbers in region.

"Throughout the pandemic, a lot of these communities that are closer to the South Region of San Diego County area and closer to the border have become disproportionately affected by COVID-19," says Adriana Bearse, the Program Manager at San Ysidro Health.

Bearse says her clinics have been working tirelessly to fight the pandemic. She's disappointed that new numbers show the region is still a COVID hot spot.

According to county data released Wednesday, the ZIP codes 92173 and 92154, which make up San Ysidro and Otay Mesa, have the highest 14-day COVID case rate in the county, at more than 242 cases per 100,000 people.

Some experts say those numbers are shocking because those two zip codes also have two of the highest vaccination rates in San Diego.

County data shows the 92173 zip code is over 99.9% fully vaccinated, which ranks first among all Zip Codes in the County.

The 92154 zip code has an 86% vaccination rate - the 4th best in the County.

"At first sight, these two numbers certainly don't agree with each other," says Dr. Hai Shao, the Infectious Disease Specialist at Sharp Chula Vista.

Dr. Shao calls the number discrepancy is misleading. He explains the vaccine rate is cumulative over the last year, while the case rate is more like a snapshot of the current situation.

Meanwhile, San Ysidro's vaccination rate may be getting a boost from people crossing the border. County numbers show 40,181 people "fully vaccinated" in the 92173 ZIP code. But recent census data shows the total population is just 27,097.

County officials didn't respond to questions about that discrepancy. But Dr. Shao and Bearse believe people who live in Tijuana but work in the United States may be crossing the border for a vaccine and using 92173 as their ZIP code. That could be inflating the vaccination rate of the area.

Shao also thinks the high case rate is proof that vaccine immunity wanes over time. People who got their shots at the beginning of the rollout are more susceptible to infection and need to get a booster.

"Their immunity may not be as good as they were in the spring," he says. "As a result, these people are becoming more and more vulnerable to the new infections."

Bearse says that's troublesome because many people in those ZIP codes live in multi-generational housing or work in front-facing, essential jobs. They come into contact with a lot of people every day.

"Factors such as these are increasing their risk levels when it comes to COVID-19," Bearse says. "That's something that we've seen really throughout the pandemic."

To fight back against breakthrough infections, Bearse says the San Ysidro Health system has begun outreach on the importance of booster shots. That comes in addition to a robust outreach program about safety measures and other health concerns.

"We want to try to reach as many people as possible," she says.

For Dr. Shao, the South Bay case rate serves as a warning to the rest of the county. He says everyone needs to stay vigilant against COVID-19, especially as new variants emerge.

"People cannot afford to be complacent," says Dr. Shao. "That's the key. Get yourself vaccinated."