Study Finds Vaccine Adherence Among Susceptible Health Workers is Suboptimal

Vaccine-preventable diseases are resurging across the world as vaccination uptake has dwindled. With measles and mumps outbreaks popping up throughout the United States and Europe, it is critical that health workers are up-to-date on their vaccinations.

In a new study, a team of investigators from Maggiore Hospital of Lodi in Lodi, Italy, set out to measure whether non-immune health workers were being vaccinated against measles, mumps, rubella, and varicella in order to prevent infections and reduce the likelihood of nosocomial transmission to their patients.

The findings of the study were presented in an oral abstract presentation at the European Congress for Clinical Microbiology and Infectious Diseases (ECCMID 2019).

For the investigation, the study team evaluated 2700 health care workers’ susceptibility to vaccine-preventable diseases, as well as their levels of vaccination adherence. The health workers were all employed at 4 hospitals in Lodi, which is located in Lombardia, a Northern Italian region.

As part of the investigation, health workers from the hospital were asked to submit blood samples between August 2017 and February 2018. Susceptibility was established via serologic screening, instead of collecting medical histories.

The samples were tested using commercial ELISA for anti-measles, mumps, rubella, and varicella immunoglobulin G (IgG) via Enzygnost and Dade Behring. The antibody levels were documented as positive, equivocal, or negative, and vaccinations with proQuad, Priorix, or Varivax were proposed to the health workers with equivocal or negative IgG results.

The investigators report that 2204 of 2610 health workers were tested, 70% of whom were female. The overall adherence rate (AR) was 84%. In total, 1487 members of the nursing staff and laboratory technicians were tested (AR of 89%), along with 298 medical staff (AR of 66%), and 198 administrative personnel (AR of 89%). The mean age of the health workers was 39 years, but ranged from 23 to 70 years, including 168 workers born before 1957.

The investigators found that 95.7% of the health workers were immune to measles, 89% to mumps, 95.5% to rubella, and 97.2% to varicella. However, 180 health workers were non-immune to at least 1 disease (6.9%), 12 (0.4%) participants were negative for both mumps and measles, and 9 (0.3%) were negative for both mumps and rubella. Although those born before 1957 were not all positive, they did have higher prevalence of immunity. Results indicate that seroprevalence was higher among those employed in infectious disease and pediatric departments.

Among non-immune health workers, the vaccination rate was 58%. Overall, susceptible nurses were found to be more likely to receive an immunization than individuals in different professions. Additionally, the investigators note that the total cost of screening and vaccination in this study was 23,000 Euros.

“Immunization rates are high, but an important proportion of employees is not immune to mumps,” the investigators wrote in their conclusion, noting that overall vaccine adherence among susceptible health care workers is suboptimal.

The study, “Susceptibility of healthcare workers to measles, mumps, rubella, and varicella,” was presented in an oral abstract presentation on April 13, 2019, at ECCMID 2019 in Amsterdam, the Netherlands.