A modern measles outbreak: understanding maternal immunity and impact on postpartum vaccination uptake

Vaccine Hesitancy Phenomenon Evolution during Pregnancy over High-Risk Epidemiological Periods-"Repetitio Est Mater Studiorum"

(1) Background: The recent epidemiological events were high-stress level generators for humanity, particularly for pregnant women, influencing their attitude, behavior, and decisions regarding vaccination during pregnancy or regarding their future child. The aim of this study was to analyze the anti-pertussis vaccination decision-shaping factors in pregnant women during two epidemiological periods: the measles epidemic and the COVID-19 pandemic. (2) Methods: Two groups of pregnant women were invited to be part of a medical education program, having as the main theme the infectious disease risks and their prevention through vaccination. Before launching the program, participants received a 12-item questionnaire. From a total number of 362 pregnant women enrolled in the study, 182 participated in 2019, and 180 participated in 2022. (3) Results: The socio-demographic data revealed that the age of pregnant women participating in medical education programs increased in 2022 by 1.7 years (p < 0.01). In vitro fertilization was reported in a significantly higher proportion (20% in 2022 vs 9.8% in 2019, p < 0.01). Participation in community-initiated educational programs almost doubled during the pandemic time from 18.7% in 2019 to 33.9% in 2022 (p < 0.01). Pertussis vaccine acceptancy (VA) dropped from 85% in 2019 to 44.4% in 2022 (p < 0.01) (4) Conclusions: In this study, we reported fast-growing vaccine hesitancy and severe declared vaccine reluctance. The results of this complex long-term study, which evaluated pregnant women over several years, showed a five-fold increase in the percentage of pregnant women who disagreed with personal pertussis vaccination. This draws attention to the risks of pertussis epidemic outbreaks in pregnant women and their future infants in the first couple of months of life before the initiation of vaccination.

Investigation of the Seroprevalence of Antimeasles Immunoglobulin G Antibody in Students at Shiraz University of Medical Sciences

Measles is an acute, highly contagious disease with a high mortality rate in children. Although vaccination has reduced measles incidence, outbreaks still occur. Therefore, in this study, we aimed to investigate the frequency of antimeasles immunoglobulin G (IgG) antibody (Ab) among students at Shiraz University of Medical Sciences (SUMS). Four hundred fifty SUMS students were enrolled in this cross-sectional study. Information on demographics and measles vaccination history was collected using a questionnaire. Participants were divided into two groups, including A and B, according to routine doses of measles vaccine and the national measles/rubella immunization program. The antimeasles IgG Abs were tested using a commercial Enzyme-Linked Immunosorbent Assay Kit. Participants ranged in age from 18 to 48 years, with a mean age of 22.2 (±4.3). Fifty percent of the subjects were male. Our results showed that 63.6% of the cases were positive for antimeasles IgG Abs. The seroprevalence of IgG Abs between groups A and B did not differ significantly (p = 0.612). There was also no significant correlation between the seroprevalence of antimeasles IgG Abs and the age (p = 0.43) or sex (p = 0.24) of the subjects. The results showed that the frequency of antimeasles IgG Abs is lower than required to prevent the measles virus from circulating. Therefore, a booster vaccination may be necessary.

Risk Factors for Measles Nonimmunity in Rubella-Immune Pregnant Patients

OBJECTIVES

 Measles immunity testing, unlike that for rubella, is not currently part of prenatal screening even though immunity to both is conferred by the measles-mumps-rubella (MMR) vaccine. Although endemic transmission of measles was declared eliminated in the United States in 2001, outbreaks have continued to occur. Given the risks associated with measles infection during pregnancy, we sought to identify risk factors for measles nonimmunity (MNI) in rubella-immune (RI) pregnant individuals.

METHODS

 We performed a retrospective observational cross-sectional study of patients receiving prenatal care and delivering at two university hospitals and a county hospital in Southern California from April 1, 2019 to February 1, 2021. Inclusion criteria were pregnant individuals ≥18 years old who had serological testing for rubella and measles during pregnancy. Demographic data were extracted from electronic medical records, including results of serological testing and chronic medical conditions. All subjects were rubella immune, and we compared measles-immune (MI) with MNI groups.

RESULTS

 In total, 1,813 RI individuals were identified, with 1,467 (81%) MI and 346 (19%) MNI individuals. Variables associated with an increased risk of MNI included having public health insurance (adjusted relative risk [aRR]: 1.56; 95% confidence interval [CI]: 1.24, 1.97) and Hispanic ethnicity (aRR: 1.37; 95% CI: 1.06, 1.78). Black race was associated with a decreased risk of MNI (aRR: 0.52; 95% CI: 0.29, 0.91). Birth year before 1989 demonstrated a trend toward increased risk of MNI, but this did not reach statistical significance (aRR 1.23; 95% CI: 1.00, 1.52). No differences were seen between the two groups for medical comorbidities.

CONCLUSION

 Our study is the first to demonstrate risk factors for measles MNI in patients with documented rubella immunity. In the absence of universal measles serological screening recommendations, the risk factors identified could help guide clinicians in selective screening for those at risk of needing postpartum MMR vaccination.

KEY POINTS

· The rate of measles nonimmunity is higher than previously reported.. · Hispanic ethnicity and use of public insurance are risk factors for measles nonimmunity.. · The current recommendation for history-based screening for measles immunity is likely insufficient..