Waning immunity and potential asymptomatic infection in 3-7 years old children who received one dose of measles-mumps-rubella vaccine: A 4-year prospective study

Epidemiology of measles clusters/outbreaks during 2016-2017 in Oman

Objectives

The epidemiology of measles in Oman has shown a decreasing trend since the introduction of vaccines with high coverage, even at the district level. Oman achieved elimination status in 2019. Currently, measles epidemiology is characterized by a small number of imported and importation-related cases with limited spread in the community. The main aim of the study is to describe the epidemiology of major measles outbreaks in Oman during 2016-2017.

Methods

This study involved a descriptive case-based record review of the national surveillance database for fever and rash illness.

Results

A total of 231 measles cases were reported during 2016-2017. Of the reported cases, 209 (90.5%) were laboratory-confirmed, 16 (6.9%) were clinically compatible, and six (2.6%) were epidemiologically linked cases. There were 10 clusters/outbreaks comprising 191 cases (185 laboratory-confirmed cases and six epidemiologically linked to a confirmed case) in various governorates of Oman during 2016-2017. The study population had a mean age of 11.4 years, ranging from 0.2 to 55 years across the outbreaks. The median age was 9 months. Approximately 50.7% of the cases involved infants aged ≤12 months, who were not yet eligible for measles vaccination. The second most affected age group were individuals aged 20-35 years. The largest and the longest cluster during 2016-2017 occurred in Dhofar and Sharqiyah, involving 90 cases attributed to genotype B3, which lasted for 32 weeks.

Conclusions

Multiple small outbreaks occurred simultaneously but were too brief to allow any particular genotype to establish itself as an endemic strain.

Phase III, open-label, single-arm study of a new MMR vaccine (JVC-001); measles AIK-C, mumps RIT 4385, rubella Takahashi, as a second vaccine dose in healthy Japanese children aged 5-6 years

PURPOSE

This Phase III, multicenter, open-label, single-arm study evaluated the safety and immunogenicity of the measles-mumps-rubella (MMR) combined vaccine, JVC-001, as a second MMR vaccination.

METHODS

Healthy Japanese children aged 5-6 years received a single dose of JVC-001 following a first measles, mumps, and rubella vaccination (measles-rubella bivalent and mumps monovalent vaccine [Hoshino or Torii strain] or JVC-001) or the MMR vaccine received between ages 1 to <4 years. Immunogenicity was evaluated using antibody titers before and after vaccination (Day 1/Day 43). The primary endpoint was the seroprotection rate of antibody titers against each virus; geometric mean titer (GMT) was also evaluated. Adverse events (AEs) and adverse drug reactions (ADRs) were monitored.

RESULTS

One-hundred participants completed the study. The seroprotection rate of antibody titers against measles, rubella, and mumps virus (genotype D) were 100.0 % (95 % confidence interval [CI] 96.4 %, 100.0 %), 100.0 % (95 % CI 96.4 %, 100.0 %), and 100.0 % (95 % CI 96.3 %, 100.0 %), respectively. GMT (fold) increases (Day 1 to Day 43) were 16.0 to 55.7 for measles virus, 35.5 to 99.0 for rubella virus, and 25.7 to 89.5 for mumps virus (genotype D). Solicited ADRs occurred in 40.0 % of participants (injection site, 34.0 %; systemic, 13.0 %).

CONCLUSIONS

The second MMR vaccination with JVC-001 demonstrated sufficient antibody coverage against all three viruses; the safety profile was tolerable.

CLINICAL TRIAL REGISTRATION

jRCT2080225022.

Assessment of mumps-containing vaccine effectiveness by dose during 2006 to 2020 in Quzhou, China

Mumps cases were reported frequently when a routine dose measles-mumps-rubella(MMR) achieved high coverage in Quzhou. The supplementary immunization activities (SIA) using measles mumps (MM) was conducted to control mumps outbreaks. The effectiveness of one and two doses of mumps-containing vaccine (MuCV) was assessed using surveillance data in this study. Mumps cases and immunization information were retrieved from the National Notifiable Disease Reporting System (NNDRS) and the Zhejiang Provincial Immunization Information System (ZJIIS), respectively. Mumps cases of children born from 2006 to 2010 were included. Vaccine effectiveness by dose was calculated using the screening method. A total of 956 mumps cases were identified, of whom 754 (78.9%) had received one dose of MuCV; 108 (11.3%) had received two doses; 94 (9.8%) were unvaccinated. The coverage of one-dose MuCV in the 2006-2010 birth cohorts ranged from 91.6% to 98.9%. Except the 2009 birth cohort in which the coverage of two doses of MuCV was 55.1%, the others were less than 10%. Vaccine effectiveness (VE) of one dose ranged from 47.4% to 86.0%, while VE of two doses ranged from 64.0% to 92.4%. The VE of one and two doses of MuCV waned over time, but the VE of two doses was consistently higher than that of one dose in the same period. The vaccine schedule with two-dose MMR should be implemented among children in Quzhou. The optimal age for the second dose needs to be further evaluated.

Knowledge, Awareness, and Prevention of Norovirus Infection among Kindergarten Parents in Chengdu, China

Human noroviruses (HuNoVs) are a leading cause of acute gastroenteritis among children in China. However, little is known about parents' knowledge of HuNoV infection and their understanding of how to prevent and control the disease. Therefore, we performed an exploratory survey to assess the level of knowledge of HuNoV infection among kindergarten parents. A cross-sectional survey was conducted by investigating kindergarteners' parents through an online self-administered questionnaire between October 2020 and November 2020 in Chengdu, China. A total of 771 questionnaires were received with valid responses, and 81.97% of respondents had heard about NoV before. Among parents who had heard about HuNoV before, they had a poor awareness of incubation period, duration, and high-incidence seasons of HuNoV infection. The respondents also had a low-level awareness of how to clean the places contaminated by vomitus or stool. The multiple-regression analysis confirmed that factors associated with good knowledge regarding HuNoV infection were level of education, occupation, history of infection, and HuNoV learning experience. The most expected approach to learn about HuNoV among parents was the internet, followed by knowledge training in kindergartens, community information, and television. This is the first study to assess kindergarten parents' knowledge and awareness of HuNoV infection. The survey results provide insights that would help in developing effective strategies and educational materials to prevent and control the disease.