The COVID-19 vaccine substation near Petco Park will close on Friday and Saturday due to bone-chilling winter storms that have swept across much of the U.S. and frozen vaccine supply lines.
The place can be closed Sunday and Monday, depending on when the next batch of doses arrives. Anyone with an appointment during the closing will be rescheduled through UC San Diego’s MyChart system and should check for an email notification, according to county and UCSD spokespersons.
Other immunization sites in San Diego County are also being affected. A website run by Palomar Health in downtown Escondido is closing on Friday, but resumes operations on Saturday. And a superstation administered by CSU San Marcos and the municipality will, for now, offer only second doses of vaccine. The same is true for more than a dozen smaller vaccine sites across the region. The first appointments will be automatically rescheduled through MyTurn, the state’s online vaccine registration and scheduling system.
Sharp HealthCare, which runs mass immunization stations in Chula Vista and La Mesa, continues to offer Pfizer first and second dose vaccines from its existing supply and will reschedule Moderna’s vaccination appointments.
Scripps Health, which operates a super station at Del Mar Fairgrounds, has enough vaccine to meet commitments over the weekend, according to a spokesman. And UCSD will continue to manage a campus location at RIMAC Arena to vaccinate UCSD Health staff, faculty and patients.
Of all the things that can delay the release of the vaccine in San Diego County, the weather may seem the least likely culprit. Temperatures were around 60 degrees at San Diego International Airport on Thursday afternoon, just a few miles away from the Petco Park super station.
But about 70 percent of the United States is covered in snow, according to the National Operational Hydrologic Remote Sensing Center. This includes Michigan and Massachusetts, where Moderna and Pfizer are manufacturing much of their vaccine supply, respectively.
This will be the second time that the city center super-station closes, as the site took a break from Sunday to Tuesday after a batch of Moderna vaccine did not arrive in time. County officials say they still do not know why the shipment was delayed last week.
“A second set of delays will have very significant impacts on our system,” said county supervisor Nathan Fletcher during the coronavirus briefing on Wednesday. “I think people understand that we don’t control the climate and we don’t control the arrival of vaccines.”
Many San Diegans who will be affected by the delays are those who need second doses, as the vaccines from Pfizer and Moderna require a booster injection three and four weeks later, respectively, to maximize immunity against the coronavirus. There are about 366,000 San Diegans who have received their first dose, but still need the second, according to the county’s online vaccine panel.
It is unclear exactly how many people have appointments scheduled for the next few days, but a UCSD spokesman said that almost all of this week’s appointments at Petco Park were for a second dose. The substation normally vaccinates about 5,000 San Diegans a day.
Any delay in second doses can increase frustration and worry. But Dr. Mark Sawyer, an infectious disease specialist at Rady Children’s Hospital, says there is no real cause for alarm.
“While these problems with the vaccine supply may delay your second dose, in the end it will be okay,” said Sawyer. “As long as you finally get the total number of doses you should be getting, it gives you the same level of protection.”
He is well versed in the subject. Sawyer served on committees that recommended that the Food and Drug Administration authorize the Moderna and Pfizer vaccines. He also serves on a vaccine advisory committee for the Centers for Disease Control and Prevention.
Sawyer’s comments echo the guidance of the CDC, which advises obtaining the second dose of the COVID-19 vaccine six weeks after the first – although the agency adds that there is no need to restart the process if the second injection comes later.
There are many other vaccines that require more than one dose, including vaccines against tetanus, measles and whooping cough. In such cases, says Sawyer, the exact timing of follow-up doses is not critical and is, to some extent, arbitrary.
Case in point: Pfizer and Moderna require a second injection 21 and 28 days later, respectively. Why not 22 and 29 days later? Because it’s easier to tell people to come back in three or four weeks, and that’s how the clinical trials that tested the vaccines were set up.
Still, there are some basic principles that guide the timing of second doses. It takes about two weeks to build up an initial response to the vaccine, and you would not want to receive a second injection while you are still reacting to the first. Many of the cells activated by the vaccine eventually die as the immune response decreases. But subsequent doses reactivate that response, producing higher levels of antibodies, which are Y-shaped proteins that coat a virus and can block infection, and T cells, which can kill cells infected by the virus.
The main reason for taking the second dose sooner or later, says Sawyer, is that the current vaccines are about 95% effective in preventing COVID-19 in people who received both vaccines. Many older adults can use this protection; people aged 65 and over are responsible for 80 percent of COVID-19 deaths, according to the CDC.
“It is better to make sure that people at high risk are fully immunized, because they are (more) likely to get really sick,” he said.
Although vaccine distribution in the region has not yet reached the majority of San Diegans, COVID-19’s local metrics continued to improve gradually. On Thursday, the county reported 36 deaths from COVID-19 and 810 new infections. That’s a small increase in cases, but the county released nearly 20,000 test results on Thursday, compared with almost 14,000 on Wednesday. The most recent report points to 95 new COVID-19 hospitalizations and 772 total hospitalizations; almost a month ago, there were about 1,700 patients with COVID-19 in hospitals in the region.