‘There doesn’t have to be the surge we saw last year’: Scientists weigh in on 2nd holiday season with COVID

UC San Diego epidemiologist Andrea LaCroix
“Vaccination plus behavioral changes is the winning combination to safely get through the holidays,” says UC San Diego epidemiologist Andrea LaCroix.
(Courtesy of Andrea LaCroix)

It’s hard to believe, but this time last year, San Diego was on the cusp of receiving its first shipment of COVID-19 vaccines. Since then, more than 38,000 residents of La Jolla’s 92037 ZIP code have received at least one shot.

But are vaccinations and boosters enough to ensure a safe holiday season this year?

“Vaccination plus behavioral changes is the winning combination to safely get through the holidays,” said UC San Diego epidemiologist Andrea LaCroix.

She broke down how this year’s holidays are expected to compare with the COVID-hampered 2020 season.

In October last year, state guidelines allowed for private outdoor gatherings of up to three households. Gatherings were recommended to be two hours or less, with everyone wearing face coverings and participants staying at least six feet from people not in their household. Those in high-risk groups, such as older adults and people with chronic medical conditions, were urged not to attend gatherings.

A month later, San Diego County fell into the most restrictive purple tier of the state’s coronavirus risk framework after two weeks of case numbers higher than seven per 100,000 residents.

Three weeks after that, a state order expanded COVID-related restrictions, mandating closure of all onsite restaurant dining, museums, aquariums, playgrounds and salons throughout Southern California.

Then in late December, UC San Diego received shipments of Moderna’s and Pfizer-BioNTech’s COVID-19 vaccines.

In mid-December 2020, the 92037 ZIP code had 711 registered cases of the coronavirus that causes COVID-19. In just under a year, that number climbed to 2,375 cases.

In December 2020, the rolling average percentage of positive cases among tests countywide jumped from 6.2 percent at the beginning of the month to 11.2 percent by the end of the month. The average stayed above 10 percent until late January 2021.

Comparatively, the rolling average in November this year stayed in the 2 percent range, peaking at 2.9 percent.

San Diego County saw a spike in positive coronavirus tests around the holidays of 2020.
San Diego County saw a spike in positive coronavirus tests around the holidays of 2020 — a surge that scientists hope can be prevented this holiday season with vaccination and booster shots and behavioral changes.
(Screenshot by Ashley Mackin-Solomon)

Though the steadily increasing number of vaccinated and “boosted” residents (those who have received both doses of a two-dose vaccine regimen or one dose of a one-dose regimen and then the booster shot) likely will help keep case numbers down, LaCroix wonders how much it will help if people don’t adopt the behavior changes that were suggested last year.

In December 2020, “most of us did not have vaccines ... and we had a huge COVID surge” soon after the holidays, LaCroix said.

This year, with people wanting to avoid repeating the 2020 heartache of not seeing loved ones for the holidays, LaCroix said she “definitely” expects an increase in cases in coming weeks.

However, those who are fully vaccinated and have received a booster shot are “reasonably safe,” especially if they wear a mask in public places, she said. Plus, she acknowledged that “we can’t isolate ourselves forever.”

“Nothing is completely safe until we don’t have viral transmission in the community, but the antibody response to boosters is fantastic,” she said. “It puts people in a good place to get a booster before the holidays.”

Dr. Davey Smith, head of infectious-disease research at UCSD, agreed that “people should be getting vaccinated and getting their boosters.”

Amid concern about the newly discovered Omicron variant of the coronavirus, Smith said scientists are just beginning to understand Omicron but “the vaccines we have now should work quite well against it.”

“There doesn’t have to be the surge we saw last year, but it’s up to us,” LaCroix said. “People who aren’t vaccinated or are vaccinated but not boosted and don’t wear a mask are high-risk, and there are many people like that. Before you travel, get a booster. Wear a mask.”

LaCroix said she plans to travel to see her children in Seattle because she has seen them only once since the onset of the pandemic. She said she has received both doses of a vaccine, plus a booster shot.

“I feel apprehensive about flying because I haven’t been on a plane in so long, but I think we are all fatigued and are ready to figure out how to live our lives during this pandemic for however long it lasts,” she said. “Some people will do everything, some will do nothing.”

At a UCSD panel discussion on COVID held Dec. 2, several speakers echoed LaCroix’s comments.

Associate professor of ecology, behavior and evolution Justin Meyer said it’s not too late to get the booster and have it be effective for the holidays. “The booster seems to kick in faster than the original dose or doses … because the [booster] reminds your immune system of what it knew already and kicks in in a couple of days,” he said. “But still wear a mask and wear a good mask. ... Forget about social pressure.”

Professor of medicine Natasha Martin said: “If you are not vaccinated, get vaccinated. The vast majority of people in the hospital are unvaccinated.”

Molecular biology professor Elina Zuniga suggested keeping gatherings small and advised that those who are not vaccinated get tested before gathering.

Meyer said he will recommend that the students in his lab quarantine at home for a week if they travel out of the area and see family and/or friends. “That might be a little bit over the top … but it’s a good time to do that,” he said.

Also Dec. 2, UCSD told its nearly 43,000 students that they should get tested for the coronavirus “as soon as possible” if they traveled over the Thanksgiving break, whether they are vaccinated or not.

— San Diego Union-Tribune staff writer Gary Robbins contributed to this report.