乌鸦传媒

Certain types of vaccines contributed to a risk of shoulder injury following vaccination, a large, retrospective population-based dataset found, although the absolute risk was small.

Pneumococcal conjugate vaccines were tied to the highest risk of post-vaccination shoulder conditions of any vaccine, while among influenza vaccines, quadrivalent influenza vaccines were associated with the highest risk, reported Chengyi Zheng, PhD, of Kaiser Permanente Southern California in Pasadena, and colleagues.

Notably, only 4.6% of shoulder conditions were specified to be "shoulder bursitis" and 70.6% of those occurred following influenza vaccinations, they wrote in the

Overall, "the incidence of shoulder conditions after vaccination was low," the authors stated, but "[g]iven the high burden of shoulder conditions, clinicians should pay attention to any factors that may further increase risks."

They noted that the "mechanism for shoulder conditions after vaccination is hypothesized to be needle overpenetration into the shoulder joint, which results in immune-mediated inflammation," and added that while immunization guidelines recommend a 1-inch needle, this may cause overpenetration in about half of adults.

The authors said that shoulder injury related to vaccine administration (SIRVA) was added to the National Vaccine Injury Compensation Program in 2017, as evidence supported "a causal relationship" between the injection and deltoid bursitis. However, there is a paucity of population-based studies on the condition beyond case reports and case series.

Zheng's group added that while population-based studies have been scarce due to the cost of manually reviewing medical records, they used a validated natural language processing algorithm, as well as chart review, to estimate both the risk of shoulder injury, and factors that contributed to it.

They examined data from Kaiser Permanente Southern California members, ages 3 years and up, who received an intramuscular vaccination in the deltoid muscle from April 1, 2016 to Dec. 31, 2017. Overall, there were 3,758,764 eligible vaccinations.

After factoring in the natural language processing algorithm and manual chart review, Zheng's group found 371 cases, for an incidence of 0.99 (95% CI 0.89-1.09) per 10,000 vaccinations. Of the 371 cases, the authors noted that 358 had "explicit documentation" that they occurred post-vaccination.

They reported that shoulder conditions were most common among adults ages 65 and up (1.67 per 10,000 vaccinations, 95% CI 1.43-1.95), and higher among all adults (1.22 per 10,000, 95% CI 1.10-1.35) than children ages 3-17 (0.05 per 10,000, 95% CI 0.02-0.14). Out of 750,000 pediatric vaccine recipients, there were only four cases of shoulder conditions linked with vaccination.

Median age of adults with shoulder conditions following vaccination was about 62, and 65% were women. Nearly all (94%) shoulder conditions occurred within 2 days of vaccination.

The age- and sex-adjusted incidence of shoulder conditions following influenza vaccination was 1.13 per 10,000, but it was highest following pneumococcal conjugate vaccine PCV13 (2.83) and lowest following hepatitis A vaccine (0.76). Those who received simultaneous vaccination had an incidence of 2.06 per 10,000, the authors said.

Among influenza vaccines, the cell culture-based inactivated influenza vaccine quadrivalent (ccIIV4) had the highest rate of shoulder conditions (2.21 per 10,000), while the standard-dose inactivated influenza vaccine trivalent (SD-IIV3) had the lowest incidence (0.88 per 10,000).

Examining demographics, the authors reported that female sex, more outpatient visits in the 6 months prior to vaccination, and a lower were all associated with increased risk of shoulder conditions after intramuscular vaccinations.

Study limitations included the fact that shoulder conditions following vaccination may be underestimated, unmeasured confounding, and that shoulder conditions may not be related to vaccination at all.

"More research is needed to better understand the risk factors and causal pathways for shoulder conditions after vaccination," the authors concluded.

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