23-valent pneumococcal vaccine linked to necrosis, but risks do not outweigh benefits

Key takeaways:

• There were less than 0.2 cases of injection site necrosis per million 23-valent pneumococcal vaccine doses.
• Researchers said the overall benefit-risk balance for the vaccine is still favorable.

There have been some reports of necrosis at the injection site following receipt of the 23-valent pneumococcal vaccine, but the vaccine’s overall benefit-risk balance “remains favorable,” researchers wrote in JAMA Internal Medicine.

Once a vaccine has been approved by the FDA and administered to a large, diverse population, rare safety events that clinical trials are not typically equipped to detect may emerge, Brendan Day, MD, MPH, of the FDA’s Office of Biostatistics and Pharmacovigilance at the Center for Biologics Evaluation and Research, and colleagues wrote. Therefore, postmarketing surveillance is critically important when it comes to characterizing the safety profile of licensed vaccines.

In 2020, the FDA detected a safety signal of injection site necrosis — “a rare complication for many vaccines and injectable drugs,” the researchers wrote — after receiving the 23-valent pneumococcal vaccine. Day and colleagues conducted a study to describe the evaluation and outcomes of this safety signal.

The CDC and FDA use the Vaccine Adverse Event Reporting System (VAERS), a passive surveillance system that relies on individuals to report adverse events, to monitor postmarketing safety of U.S.-licensed vaccines.

The researchers queried the VAERS database in May 2020 and performed a case series review of reports, including submitted medical records such as pathology reports and clinician notes. They defined a case using adapted criteria for a local reaction at or near the injection site. They also used vaccine distribution data from the manufacturer to calculate a reporting rate.

Day and colleagues found that the injection site necrosis reporting rate was less than 0.2 cases per million vaccine doses distributed.

“Often, skin necrosis developed after a progression of typical local symptoms (eg, redness, swelling, and pain),” they wrote. “These reports are consistent with published descriptions of injection site necrosis.”

The researchers identified 104 VAERS reports, but just 48 met their case definition, 43 of which were for skin necrosis. Of the remaining cases, two were necrosis of fascia, one was of fat and fascia, one was muscle and one was fat, fascia and muscle. Half of the cases were in the United States. The median age for patients with skin necrosis was 67 years; 12 patients were immunocompromised; and most — 36 — were women.

Fewer than half of cases (n = 23) had serious reactions, including one fatality that was unrelated to vaccination. Also, 26 patients required surgical intervention — most commonly debridement — and 17 patients required hospitalization. Eight underwent more than one surgical procedure, and three required a skin graft.

The researchers wrote that there were too few cases of muscle, fat and fascia necrosis to draw any meaningful conclusions.

“The Pneumovax 23 U.S. package insert has been updated to include injection site necrosis in section 6.2, PostMarketing Experience,” Day and colleagues concluded. “The overall benefit-risk balance for this vaccine remains favorable.”