AS more Americans ready for their second COVID-19 vaccine shot, some patients are falling through the cracks of an increasingly complex web of providers and appointment systems.

While many people are getting their required second doses, the process is taking a toll on some of the most vulnerable - older adults who in many cases rely on family members or friends to navigate complex sign-up systems and inconvenient locations.

Available vaccines need to be given as two separate doses weeks apart, and confusion is further taxing an already challenged health care system. Houston's health department on Friday told those seeking a second dose to be patient, saying the volume of calls was creating long wait times at its call center.

As of Monday, 26 million people in the United States had received a first vaccine shot, and almost 6 million had the second, according to the U.S. Centers for Disease Control and Prevention (CDC). The CDC has also said states lag in reporting data so it is unclear if that might affect the dose counts.

“There's going to be some delay in getting second doses,” said Beth Blauer, Executive Director at the Centers for Civic Impact at Johns Hopkins University, who is tracking vaccination data for the university’s Coronavirus Resource Center.

She had expected the number of first doses to plateau as priority populations began to get second doses, but that tapering off was happening slower than expected.

“We're still seeing the first dose climb which means that there's going to essentially be an unrealistic expectation that you're going to get your second dose, because we know that there's finite supply.”

SECOND SHOT PROCEDURES

Practices vary. Seminole County in Florida schedules follow-ups during the 15-minute observation period after people get their first shots. New York's Onondaga County holds off on scheduling second appointments until days before the shot.

After an online system showed no appointments, Stacey Champion secured a second appointment for her 78-year-old friend Dan Pochoda at Cardinal Stadium in Phoenix, Arizona - at 1:51 a.m. on Feb. 9. It took several calls to get even that, Champion said.

"If they had been saving appointments for second doses, would they really need to send people way out to the edges of the city in the middle of the night?" Champion asked.

Many providers expect their vaccine allocations to fall sharply this week.

"When this started, it was only for hospitals. Now a smaller pot needs to be divided between many more - the pharmacies, the mega sites and everyone else," said Felipe Osorno, executive administrator of continuum of care operations and value improvement at Keck Medicine of the University of Southern California.

People in recent days have been showing up at USC hospitals seeking their second vaccine dose, saying their original vaccine provider could not confirm an appointment, Osorno said.

On Twitter, concerns about getting the second shot are mixed with triumphant tweets by many who got follow-ups on time, without drama.

St. John's Well Child and Family Center, a network of public health centers in South and Central Los Angeles, is running nine vaccination clinics, and began administering second doses on Jan. 25 after sending email and telephone reminders to patients.

"We screamed and yelled" to secure second doses on top of meeting the need for first shot appointments, said Jim Mangia, the center's president, who added most people are returning.

West Virginia, a leader in getting shots into arms, hired critical event management firm Everbridge to manage scheduling as it opens up vaccinations to more groups.

"Any time there's ambiguity, that's not a good feeling," said Andy Malinoski, marketing director for West Virginia's Department of Commerce.

Guidelines call for a second shot of Moderna Inc's vaccine four weeks after the first dose, while the gap is three weeks for the Pfizer Inc/BioNTech vaccine. The CDC has said an interval as long as six weeks is acceptable for either vaccine.