Thousands of SC residents who skipped second COVID vaccine dose at risk of delta variant

More than 10% of South Carolinians inoculated with a dose of the Pfizer-BioNTech or Moderna COVID-19 vaccine are late for their second shot, leaving them vulnerable to infection with the highly transmissible delta variant, state health officials said.

As of Tuesday, 211,101 residents were at least a week late for their second dose, with nearly 90% of those, or 188,827, past due by more than a month, state Department of Health and Environmental Control spokesman Derrek Asberry said.

The recommended interval between shots is three weeks for Pfizer and four weeks for Moderna.

While delaying the second dose of either vaccine does not appear to weaken one’s immune response, research shows that partially vaccinated individuals fare significantly worse against COVID-19 variants like delta that make up a growing share of cases in South Carolina and the country.

“It’s very clear that one shot of the mRNA vaccines — the Pfizers and the Modernas — is not enough” to adequately protect against the delta variant, said Dr. Helmut Albrecht, medical director of the Center for Infectious Diseases Research and Policy at Prisma Health and the University of South Carolina. “We really didn’t see that with other variants.”

A Public Health England study published in May found that one dose of Pfizer was only 50% effective against the alpha variant, which until recently had been the dominant strain in the U.S., and just 33% effective against the delta variant, which now makes up the majority of new COVID-19 cases nationwide. After two doses, Pfizer’s effectiveness jumped to 93% against alpha and 88% against delta, researchers found.

A study published last month in the journal Nature found even starker differences in immune responses between people who had received one shot versus two shots. Only 13% of people effectively neutralized the delta variant after a single dose of the Pfizer vaccine, but 94% were able to do so after two doses, researchers found.

“A single dose of Pfizer or AstraZeneca was either poorly or not at all efficient against beta and delta variants,” the scientists wrote. “Both vaccines generated a neutralizing response that efficiently targeted variant delta only after the second dose.”

With delta accounting for nearly 60% of new COVID-19 cases nationwide, according to U.S. Centers for Disease Control and Prevention estimates, state health officials are concerned about the infection risk faced by the tens of thousands of South Carolinians who have foregone second doses.

“Unvaccinated people or people who are incompletely vaccinated — who got only one dose of vaccine — remain vulnerable to this deadly disease,” said assistant state epidemiologist Jane Kelly, who has warned that a surge of COVID-19 cases in South Carolina could be on the horizon due to the state’s low vaccination rate.

Just over 43% of eligible South Carolinians are fully vaccinated against the coronavirus, one of the lowest rates in the nation.

State health officials attribute a recent increase in COVID-19 cases and hospitalizations to flagging vaccinations. Weekly cases more than doubled between June 19 and July 10, and hospitalizations for COVID-19 have spiked about 40% over that span, according to DHEC data.

“Our current situation is tipping in the wrong direction,” public health director Brannon Traxler said Wednesday. “We can’t let the virus and its variants grow stronger. Getting vaccinated is how we win.”

Skipping second dose a ‘major concern’

The reasons why people fail to return for their second shots vary.

Some simply forget their second-dose appointments. Others are forced to miss their appointments and never reschedule them. Still others choose to skip their second shots fearing side effects or believing they’re sufficiently protected after a single dose.

Regardless of the reason, the lack of follow-through is a “major concern,” Asberry said.

For months, DHEC officials have waged a public messaging campaign to stress the importance of getting both rounds of the vaccines.

The agency also sends direct-mail postcards to vaccine recipients explaining the importance of returning for a second shot and instructs operators with the agency’s vaccine information line to follow up with residents who have not returned for their second jab.

“As we continue to stress, a person is not fully vaccinated unless they have both shots of the Pfizer or Moderna vaccine brands,” Asberry said. “Completed vaccinations are the number one way for people to protect themselves and their loved ones, and to end this pandemic.”

Despite health officials’ efforts, the number of people in South Carolina and across the country who are late for their second doses has continued to grow.

As of June 16, roughly 12% of people nationwide who had received one dose of vaccine and were eligible for their second shot had not gotten it, CNN reported.

Young adults, the least vaccinated demographic group in South Carolina, were the most likely to miss their second doses, according to the report.