Measles and rubella seroprevalence in a population of young adult blood donors, France 2013

Two-dose measles vaccine effectiveness remains high over time: A French observational study, 2017-2019

BACKGROUND

From 2008 to 2019, France has experienced a resurgence of measles epidemics. Surveillance data have shown that the proportion of cases vaccinated with two doses of measles-containing vaccine (MCV) increased with age, raising concerns about the duration of vaccine protection. Our objectives were to investigate age-stratified vaccine effectiveness (VE) for the second dose of MCV (MCV2) and to quantify protection levels over time.

METHODS

We analyzed data on measles cases aged 2-31 years, reported via mandatory notification to the French measles surveillance system from October 2017 to September 2019. We estimated an age-stratified VE for MCV2 using the screening method, which compares the vaccination status of cases with that of the general population. We improved this method by accounting for natural immunity, exploring four scenarios with four possible levels of natural immunity in the population. In addition, we quantified the decay rate of protection over time, by fitting an exponential decay model among individuals vaccinated in early life.

RESULTS

In the baseline analysis (absence of natural immunity), VE estimates were high in all age groups and decreased with age, from 99.6 % (95 % confidence interval: 99.3-99.8) in 2-5 years old to 91.4 % (85.1-95.0) in 26-31 years old. Accounting for natural immunity increased VE in the older age group to 93.2-99.2 % depending on the scenario. We estimated that VE was slowly decreasing over time, with an exponential decay rate of 0.0022/year (0.0017-0.0028), leading to VE of 96.7 % (96.0-97.4) 16 years after MCV2 vaccination. This decline was most compatible with scenario 2, a scenario of 4.4 % naturally immunized, non-vaccinated individuals in the 26-31 years old.

CONCLUSION

Our study confirms the continued high effectiveness of two doses of MCV with only slight degradation, decades after immunization. These findings support the importance of achieving a very high vaccination coverage with 2 doses of MCV.

Measles seroprevalence in human immunodeficiency virus-infected adults born in the era of measles vaccination

OBJECTIVE

Widespread use of the measles vaccine should lead to the elimination of this disease. Here, we study the seroprevalence of measles in a cohort of adults living with HIV born after the introduction of measles vaccine in France and attempt to identify risk factors for the absence of serum measles antibody.

DESIGN

In this multi-centre cross-sectional study, adult outpatients born after 1980 were screened for the presence of measles IgG antibody. Demographic and clinical data were obtained from the standardized electronic medical record system. Univariate and multivariate logistic regressions were performed to identify factors associated with the absence of measles antibodies.

RESULTS

Between April 2019 and April 2020, 648 participants were enrolled. The median age was 33 years, 53.6% were born outside of France, and 74% were considered as socially deprived. Plasma HIV RNA was undetectable in 86% of patients. Among 603 evaluable patients, measles serology was positive in 87.2%. Only 81.8% of the patients with documented vaccination tested positive for measles IgG. Younger age was significantly associated with the absence of measles serum antibodies ( P  = 0.004 for each 10-year lower), as was birth in France ( P  < 0.001) and absence of social vulnerability ( P  = 0.04).

CONCLUSION

The current study revealed a low seroprevalence of measles compared with that previously reported in France 6 years earlier and to the expected rate to achieve herd immunity. Checking vaccination record should be systematically carried out in patients living with HIV to fill the immunity gaps.

Prolonged Maternal Shedding and Maternal-fetal Transmission of Measles Virus

Prolonged measles virus detection in maternal saliva and blood was evidenced in 6 pregnant women. Maternal-fetal transmission was evidenced in 2 of 4 infants who were asymptomatic at birth, 21-24 weeks after maternal infection. Whereas peripartum congenital measles is severe, asymptomatic measles virus vertical transmission can occur earlier in pregnancy.

Risk of Absence of Measles Antibody in Healthcare Personnel and Efficacy of Booster Vaccination

We aimed to identify the presence of the measles IgG antibody (mIgG-Ab) in healthcare personnel and finding out who needs the measles vaccination. The history of measles vaccination was obtained from the national vaccine registry. A baseline mIgG-Ab test was performed, and the measles vaccine was administered to participants who tested negative or equivocal for mIgG-Abs. During the study, 2885 (87.3%) of the 3303 employees were tested for measles serostatus. The baseline seropositivity rate for mIgG-Abs was 91.9%. Among the 234 seronegative cases, 82.9% were born after 1985. The seroprevalence rate was lower in those who received the measles–mumps–rubella (MMR) vaccine >10 years before the testing time, especially if they were born after 1985 and if there was only one previous record of vaccination. Among the 234 seronegative cases, MMR vaccination was administered in 174 cases, of which serostatus was evaluated in 146 cases. After the first dose, positive seroconversion was achieved in 126 participants (86.3%). After a second dose, 15 achieved (75.0%) positive seroconversion. In healthcare personnel born after the period when measles incidence significantly decreased, it may be necessary to reassess their immune status for measles if more than 10 years have elapsed since the last vaccination.

Positive predictive value of seroconversion or positive rubella IgM in diagnosis of maternal rubella infection: Seven-years review of French National Reference Laboratory for Rubella

BACKGROUND

In France, as in most developed countries, childbearing age women are routinely screened for rubella antibodies to identify and vaccinate susceptible women. Immunity to rubella is usually determined by measuring the rubella virus-specific immunoglobulin G (RV-IgG). In case of seroconversion for RV-IgG and/or positive RVIgM during pregnancy, laboratories usually send serum samples to the French National Reference Laboratory (FNRL) for Rubella in order to perform complementary investigations and confirm or exclude rubella infection during pregnancy.

OBJECTIVE

Our aim is to report results of these investigations during a seven-year period (2013-2019) and evaluate the positive predictive value (PPV) of RV-IgG seroconversion or positive RV-IgM to diagnose maternal rubella infection in France.

STUDY DESIGN

Between 2013 and 2019, 5398 serum samples collected from 4104 pregnant women, were addressed to FNRL because of RV-IgG seroconversion (N=899) or positive RV-IgM (N=3205). Additional serological tests were performed, mainly immunoblot (to look for the presence of anti-E1 protective antibody) and RV-IgG avidity (to exclude or confirm primary infection).

RESULTS

Overall, for 3724/4104 (90.8 %) women, rubella primary-infection during pregnancy was formally excluded and maternal rubella primary-infection was only confirmed in 46/4104 (1.1 %) cases.

CONCLUSION

Clinicians and biologists should be particularly aware that RV-IgG seroconversion or positive RV-IgM, in the current context of low RV circulation in France are most often not rubella primary infections. PPV of seroconversion to assess maternal rubella primary infection is as low as 0.2 % (95 % CI: 0 %; 0.5 %) and PPV of positive RV-IgM is only of 1.4 % (95 % CI: 0.99 %; 1.81 %).

Epidemiology of measles during the COVID-19 pandemic, a description of the surveillance data, 29 EU/EEA countries and the United Kingdom, January to May 2020

The number of measles cases declined in European Union/European Economic Area countries and the United Kingdom in 2020. Reported cases to The European Centre for Disease Prevention and Control decreased from 710 to 54 between January and May. Epidemic intelligence screening observed a similar trend. Under-diagnoses and under-reporting during the coronavirus disease (COVID-19) pandemic should be ruled out before concluding reduced measles circulation is because of social distancing and any community control measures taken to control COVID-19.

Vaccination coverage and immunity levels against vaccine-preventable diseases in male Air Force recruits in Greece

AIM

Data about susceptibility rates in young adults are scarce. We estimated the complete vaccination rates, timeliness of vaccinations and susceptibility rates among male military recruits in Greece.

METHODS

A standardized form was used to collect data. Immunity against measles, rubella, varicella, hepatitis A and hepatitis B was serologically estimated.

RESULTS

We studied 385 recruits with a mean age of 23.5 years (range: 18.3-29.9 years). Complete vaccination rates were 94.3% for measles, 100% for rubella, 15% for varicella, 73.9% for hepatitis A and 96.5% for hepatitis B. Only 10.8% of participants were fully vaccinated against all five diseases. Timely vaccination was 47.2% for measles, 89.3% for rubella and 48.1% for hepatitis B. Recruits >23 years had a 1.5-fold increased probability for incomplete vaccinations compared to younger recruits. Laboratory-confirmed immunity rates were 80% against measles, 85.7% against rubella, 85.2% against varicella, 69.4% against hepatitis A and 77.1% against hepatitis B. It is estimated that approximately 388,696 persons aged 18-30 years are susceptible to measles, 277,640 persons to rubella, 287,736 persons to varicella, 595,664 persons to hepatitis A and 444,224 persons to hepatitis B in Greece.

CONCLUSION

Our study showed that young adults have significant immunity gaps against measles, rubella, varicella, hepatitis A and hepatitis B. Complete vaccination rates were suboptimal against hepatitis A and varicella. Strategies to access young adults and increase immunity rates through catch-up vaccination services should be investigated. A third dose of MMR vaccine should be considered for young adolescents in Greece.

Seroprevalence of measles, mumps, rubella, and varicella zoster virus antibodies among healthcare students: analysis of vaccine efficacy and cost-effectiveness

OBJECTIVE

The aims of this study are to determine the seroprevalence for measles, mumps, rubella, and varicella zoster virus (VZV) in a cohort of nursing students, to evaluate vaccination response rates of nonimmune students, and to calculate the cost of vaccinating students based on seroprevalence screening.

METHODS

A cross-sectional study was conducted August 2015-November 2016 among 326 healthy nursing students aged 14.1-18.1 years. Serum IgG antibodies were measured by ELISA. Results were analyzed by the Chi-square test; a p-value of < 0.05 was considered statistically significant.

RESULTS

The number of seropositive participants (%) was 308 (94.5%) for rubella, 295 (90.5%) for VZV, 244 (74.9%) for measles, and 219 (67.2%) for mumps. A significant correlation was found between measles IgG and age. A relationship was also observed between VZV IgG and kindergarten attendance. Response rates to measles, rubella, VZV, and mumps vaccination were 96%, 92.3%, 87.5%, 78.8%, respectively. The total cost of vaccination after IgG screening was less than vaccination without screening.

CONCLUSIONS

In this study, participants' immunity to measles and VZV was low. Prevaccination serological screening was cost-effectiveness method for preventing measles, mumps, rubella, and varicella infections. We believe that administering booster measles, mumps, and rubella (MMR) vaccine doses or developing a special MMR vaccination strategy for at-risk groups may prevent MMR outbreaks.