Vaccine In Young Adults Research Articles

Effect of Studying Abroad on Catch-Up Vaccination in Young Adults: A Study Using the Japan Pretravel Consultation Registry1

PurposeTo investigate the effect of studying abroad on catch-up vaccination coverage for measles, rubella, mumps, varicella, and tetanus during the pretravel consultation among young adult travelers. MethodsThis retrospective cohort study analyzed data from the Japan Pretravel Consultation Registry (J-PRECOR) on individuals aged 18–21 years with childhood vaccination records. Propensity score weighting was used to estimate the average treatment effect on the proportion of participants receiving catch-up vaccination. ResultsAmong 1,091 eligible participants, the catch-up vaccination need was highest for mumps (65.7%) and varicella (49.0%) and lowest for measles (9.9%) and rubella (14.0%). In the unadjusted analysis, the catch-up vaccination rate was 70.6% for tetanus, 50.9% for measles, 47.7% for rubella, 40.0% for mumps, and 23.9% for varicella. In the weighted analysis, the study-abroad group had significantly higher catch-up vaccination rates for measles (54.6% vs. 29.8%, P = 0.039), rubella (53.0% vs. 22.1%, P < 0.001), and varicella (26.8% vs. 10.9%, P = 0.002), whereas the non-study-abroad group had a higher catch-up vaccination rate for tetanus (62.4% vs. 78.4%, P = 0.024). ConclusionCompared with other travelers, the catch-up vaccination rate among travelers studying abroad was higher for measles, rubella, and varicella, but lower for tetanus. In clients planning to study abroad, vaccinations required for travel should be recommended in addition to those required by the host institution, and vaccination against highly infectious diseases with potential for complications, such as measles, rubella, mumps, and varicella, should be recommended to clients traveling for reasons other than studying abroad.

Motivators and Barriers to COVID-19 Vaccination in Young Adults Living in the USA.

High rates of COVID-19 infection and lower vaccination rates among young adults aged 18 to 26 in the United States prompted this study to examine motivating factors and barriers to COVID-19 vaccination and identify preferences in COVID-19 vaccine education. Three focus group discussions were completed. Transcribed data were analyzed using thematic analysis. Three key themes were identified including (1) motivating factors to vaccination, (2) barriers to vaccination, and (3) COVID-19 vaccination educational intervention design recommendations. Motivating factors included five relevant subthemes: civic duty, fear related to the disease process; fear related to emerging variants and breakthroughs; fear regarding the suffering of others; and freedom. Barriers included four subthemes: lack of trust, misinformation, politics, and pressure. Attempts to further educate young adults about the COVID-19 vaccine should consider strategies that target motivating factors and barriers while also making accurate information accessible through social media.

Leveling the Playing Field: Promoting Vaccine Equity for Adolescents and Young Adults.

Immunization is one the greatest prevention tools in the skillset of the general pediatrician. Ensuring that all patients, particularly adolescents and young adults, have the opportunity and access to age-appropriate vaccines should be an integral part of pediatric practice. Equitable immunization access and allocation should be afforded to adolescents and young adults to foster the health and well-being of America's next generation. This article will focus on select inequities that create health disparities disproportionately affecting adolescents and young adults of color. We seek to highlight inequities in adolescents and young adult vaccination and explore strategies for improving equity among this unique group. [Pediatr Ann. 2023;52(3):e102-e105.].

Seroconversion and persistence of neutralizing antibody response after yellow fever vaccination in patients with perinatally acquired HIV infection.

To describe the dynamics of neutralizing antibody (NAbs) response after yellow fever (YF) vaccine in young adults and adolescents with perinatally acquired HIV (pHIV). A retrospective cross-sectional study at three time points around YF vaccination and a matched case-control comparison of NAbs titers several years after YF vaccination. We selected patients who had both documented YF vaccination and perinatally acquired HIV (n = 46). The NAbs titers were measured in plasma samples from the following three time points: during the two years before (TP0), within the year after (TP1) and >1 year after (TP2) administration of the YF vaccine. The impact of perinatal infection was assessed by comparing pHIV YF vaccinees with 44 controls infected with HIV during adulthood. The median time between the YF vaccine and TP1 and TP2 was 123 days and 7.3 years, respectively. After YF vaccination, 85% of vaccinees experienced seroconversion. The proportion of pHIV patients with NAbs above the protective threshold was stable between TP1 and TP2 (91% and 86%, respectively) but levels of NAbs decreased significantly between TP1 and TP2 (P = 0.0122). The case-control analysis found slightly higher geometrical mean titers (GMT) in pHIV than patients infected during adulthood. Patients with pHIV showed high seroconversion rate and NAbs persistence at levels above the protective threshold after first YF vaccination. However, a decline in antibody levels over time suggests that at least one revaccination may be necessary to maintain circulating antibodies, contrary to recommendations for the general population.

Efficacy, Usability, and Acceptability of a Chatbot for Promoting COVID-19 Vaccination in Unvaccinated or Booster-Hesitant Young Adults: Pre-Post Pilot Study.

BackgroundCOVID-19 vaccines are highly effective in preventing severe disease and death but are underused. Interventions to address COVID-19 vaccine hesitancy are paramount to reducing the burden of COVID-19.ObjectiveWe aimed to evaluate the preliminary efficacy, usability, and acceptability of a chatbot for promoting COVID-19 vaccination and examine the factors associated with COVID-19 vaccine hesitancy.MethodsIn November 2021, we conducted a pre-post pilot study to evaluate “Vac Chat, Fact Check,” a web-based chatbot for promoting COVID-19 vaccination. We conducted a web-based survey (N=290) on COVID-19 vaccination at a university in Hong Kong. A subset of 46 participants who were either unvaccinated (n=22) or were vaccinated but hesitant to receive boosters (n=24) were selected and given access to the chatbot for a 7-day trial period. The chatbot provided information about COVID-19 vaccination (eg, efficacy and common side effects), debunked common myths about the vaccine, and included a decision aid for selecting vaccine platforms (inactivated and mRNA vaccines). The main efficacy outcome was changes in the COVID-19 Vaccine Hesitancy Scale (VHS) score (range 9-45) from preintervention (web-based survey) to postintervention (immediately posttrial). Other efficacy outcomes included changes in intention to vaccinate or receive boosters and willingness to encourage others to vaccinate on a scale from 1 (not at all) to 5 (very). Usability was assessed by the System Usability Scale (range 0-100). Linear regression was used to examine the factors associated with COVID-19 VHS scores in all survey respondents.ResultsThe mean (SD) age of all survey respondents was 21.4 (6.3) years, and 61% (177/290) of respondents were female. Higher eHealth literacy (B=–0.26; P<.001) and perceived danger of COVID-19 (B=–0.17; P=.009) were associated with lower COVID-19 vaccine hesitancy, adjusting for age, sex, chronic disease status, previous flu vaccination, and perceived susceptibility to COVID-19. The main efficacy outcome of COVID-19 VHS score significantly decreased from 28.6 (preintervention) to 24.5 (postintervention), with a mean difference of –4.2 (P<.001) and an effect size (Cohen d) of 0.94. The intention to vaccinate increased from 3.0 to 3.9 (P<.001) in unvaccinated participants, whereas the intention to receive boosters increased from 1.9 to 2.8 (P<.001) in booster-hesitant participants. Willingness to encourage others to vaccinate increased from 2.7 to 3.0 (P=.04). At postintervention, the median (IQR) System Usability Scale score was 72.5 (65-77.5), whereas the median (IQR) recommendation score was 7 (6-8) on a scale from 0 to 10. In a post hoc 4-month follow-up, 82% (18/22) of initially unvaccinated participants reported having received the COVID-19 vaccine, whereas 29% (7/24) of booster-hesitant participants received boosters.ConclusionsThis pilot study provided initial evidence to support the efficacy, usability, and acceptability of a chatbot for promoting COVID-19 vaccination in young adults who were unvaccinated or booster-hesitant.

Epidemiological impact and cost-effectiveness analysis of COVID-19 vaccination in Kenya

BackgroundA few studies have assessed the epidemiological impact and the cost-effectiveness of COVID-19 vaccines in settings where most of the population had been exposed to SARS-CoV-2 infection.MethodsWe conducted a cost-effectiveness...

Long-Term Immunogenicity upon Pertussis Booster Vaccination in Young Adults and Children in Relation to Priming Vaccinations in Infancy.

Booster vaccinations for pertussis are advised in many countries during childhood or adulthood. In a phase IV longitudinal interventional study, we assessed long-term immunity following an extra pertussis booster vaccination in children and adults. Children (9 years of age) were primed in infancy with either the Dutch whole cell pertussis (wP) vaccine (n = 49) or acellular pertussis (aP) vaccines (n = 59), and all children received a preschool aP booster. Adults (25–29 years, n = 86) were wP-primed in infancy and did not receive a preschool booster. All were followed-up for approximately 6 years. After the additional booster, antibody responses to pertussis were more heterogeneous but generally higher in adults compared with children, and additional modelling showed that antibody concentrations remained higher for at least a decade. Serologic parameters indicative of recent pertussis infection were more often found in aP-primed children (12%) compared with wP-primed individuals (2%) (p = 0.052). This suggests that the aP booster vaccination in aP-primed children offers less long-term protection against pertussis infection and consequently against transmission. Together, these data show that aP priming in combination with aP boosting may not be sufficient to prevent circulation and transmission, while wP-primed adults may benefit from enhanced long-lasting immunity.

Symptomatology, prognosis and clinical findings of myocarditis as an adverse event of COVID-19 mRNA vaccine: a systematic review

Funding AcknowledgementsType of funding sources: None.BackgroundMyocarditis, an inflammation of the myocardium in the absence of ischemic injury, may be caused by viruses, drugs, and vaccines. The Myocarditis following COVID-19 vaccinations is most commonly seen in young adult males and commonly after the second dose of the mRNA vaccine. It usually presents with chest pain, dyspnoea, palpitations but has a diverse clinical presentation and varied therapeutic response. We aim to systematically collate the symptomatology, prognosis, and clinical findings of COVID-19 vaccine adverse events causing Myocarditis.MethodFollowing the PRISMA statement 2020, a systematic search was conducted to isolate confirmed cases of COVID-19 vaccine-induced Myocarditis. By applying the BOOLEAN logic, the following keywords were used: COVID-19, SARS-CoV-2, Myocarditis, Mortality. Four databases were searched from January 2021 through August 2021: PubMed, Science Direct, Google Scholar, and Cochrane Library; the reference lists of screened studies were searched as well (umbrella methodology).ResultsIn total, 12 case reports, 10 case series and 1 cohort study with a total of 107 patients were included in the final analysis. A total of 101 male patients were recorded, and 6 were female showing male dominance. The mean age of all participants was 24.73 years(SD = 13.18), ranging from 14 to 70. The most common presenting symptoms were chest pain (47.66%), fever (35.51%), and myalgia (25.23%). Lab findings showed elevated Troponin I, CRP, and ESR levels in the majority of patients.ECG was abnormal in most of the patients, which include sinus rhythm (24%), ST-elevation (42.05%) and T wave inversion (13.08%). Echo findings include decreased Ejection fraction in 19.62% of patients while 13.08% of patients having a hypokinetic left ventricular wall. Further, CMR finding suggestive of confirmed myocarditis cases in 36% patients while rest are suspected one. Overall mortality(1.86%) was low among patients.ConclusionThere is increasing evidence for Myocarditis as a rare adverse event of COVID-19 mRNA vaccination in young adults. This evidence is strongest amongst young male patients. The majority of the patients complain of chest pain and fever. In lab findings Troponin I, CRP and ESR are usually increased and ST elevation is common in the ECG. This entity is mainly treated with nonsteroidal anti-inflammatory drugs, Colchicine, Beta-blockers, ACE inhibitors, Steroids. However, prognosis and outcomes are favourable with a very low mortality rate.

Seroprevalence of mumps among children and adolescents in Thailand, 2020

Thailand has implemented single-dose mumps-containing vaccines since 1997 and two doses since 2010. This study aimed to describe the seroprevalence of mumps among children who received one- or two-dose mumps vaccines. A cross-sectional study of 145 children (aged 3–9 years) and 422 adolescents (10–18 years) was conducted. Mumps IgG seropositivity was defined as ≥ 22 RU/mL by EUROIMMUN ELISA method. The mumps seroprevalence was higher in children (82.1%, 95% CI 74.8–87.9) compared to adolescents (41.7%, 95% CI 37.0–46.6) who had received at least one dose of the mumps vaccine. Among those receiving 2 doses of mumps vaccine at ≥ 5 years after their last mumps vaccination, only 51.3% had maintained IgG ≥ 22 RU/ml. There was a reverse correlation between mumps IgG titer and the time interval from the second dose of mumps vaccine (R = -0.44, p < 0.001). A booster dose of MMR vaccine in young adults may be needed.

Antibody Levels at 3-Years Follow-Up of a Third Dose of Measles-Mumps-Rubella Vaccine in Young Adults.

Mumps outbreaks and breakthrough infections of measles and rubella have raised concerns about waning of vaccine-induced immunity after two doses of measles-mumps-rubella (MMR) vaccination. In the present follow-up study, serum IgG antibodies against mumps, measles and rubella, as well as the functional neutralizing antibodies against both the mumps vaccine strain and mumps outbreak strains were measured longitudinally in young adults that received a third MMR (MMR3) dose. The mumps-specific IgG and virus neutralizing antibody levels at 3 years after vaccination were still elevated compared to pre-vaccination antibody levels, although the differences were smaller than at earlier timepoints. Interestingly, subjects with low antibody levels to mumps before vaccination benefited the most as they showed the strongest antibody increase after an MMR3 dose. Three years after an MMR3 dose, all subjects had antibody levels to measles and rubella above the internationally agreed antibody cutoff levels for clinical protection. Our data support the recommendation that an MMR3 dose may provide additional protection for those that have become susceptible to mumps virus infection during outbreaks. MMR3 also resulted in an increase in anti-measles and rubella antibody levels that lasted longer than might have been expected.

COVID-19 vaccination in children and university students.

Strategies for the use of COVID‐19 vaccines in children and young adults (in particular university students) are hotly debated and important to optimize. As of late August 2021, recommendations on the use of these vaccines in children vary across different countries. Recommendations are more uniform for vaccines in young adults, but vaccination uptake in this age group shows a large range across countries. Mandates for vaccination of university students are a particularly debated topic with many campuses endorsing mandates in the USA in contrast to European countries, at least as of August 2021. The commentary discusses the potential indirect impact of vaccination of youth on the COVID‐19 burden of disease for other age groups and societal functioning at large, estimates of direct impact on reducing fatalities and nonlethal COVID‐19‐related events in youth, estimates of potential lethal and nonlethal adverse events from vaccines and differential considerations that may exist in the USA, European countries and nonhigh‐income countries. Decision‐making for deploying COVID‐19 vaccines in young people is subject to residual uncertainty on the future course of the pandemic and potential evolution towards endemicity. Rational recommendations would also benefit from better understanding of the clinical and sociodemographic features of COVID‐19 risk in young populations and from dissecting the role of re‐infections and durability of natural vs. vaccine‐induced immunity.

Let's Chat: Development of a Family Group Chat Cancer Prevention Intervention for Vietnamese Families.

Vietnamese Americans are disproportionately affected by preventable late-stage cancers. This study capitalizes on the protective role of family networks to develop an online social media family group chat intervention promoting cancer screening among Vietnamese American families. A feasibility study was conducted to assess implementing Let's Chat, a 4-week intergenerational family group chat intervention to increase cancer screenings. Vietnamese American young adults were trained to act as family health advocates on their private family group chats and share cancer screening messages. The intervention covered material on recommended screenings for colonoscopy for those aged 45+ years, HPV (human papillomavirus) vaccination for young adults, and Pap testing for women. Ten families (n = 41) participated. Family group chat content analysis resulted in (a) sharing personal screening experiences, (b) family members being prompted to schedule cancer screening appointments after discussions in the chat, and (c) family members expressing a sense of urgency to follow up with cancer screening. Postintervention survey results revealed that 48% of participants received screening/vaccination, 77% reported intent to schedule an appointment to discuss recommended screenings, 61% reported discussing cancer screenings outside their group chat, 84% felt comfortable discussing screenings with family after the intervention, and 68% agreed that the group chat facilitated comfort around cancer screening discussions. Family members reported feeling closer to their family and greater comfort discussing cancer and cancer screening. Results from the Let's Chat feasibility study indicate promise for implementing a randomized trial conditional on grouping family chats by age and gender to increase cancer screenings among Vietnamese American families.

119. A Respiratory Syncytial Virus Prefusion F Protein (RSVPreF3) Candidate Vaccine Administered in Older Adults in a Phase I/II Randomized Clinical Trial Is Well Tolerated

BackgroundRSV is a common cause of respiratory acute illness in older adults (OA). We evaluated safety and reactogenicity of RSVPreF3 candidate vaccine in young adults (YA) and OA.MethodsIn this phase I/II, placebo-controlled, multi-country trial (NCT03814590), YA aged 18–40 years were randomized 1:1:1:1 and received 2 doses of Low-, Medium- or High-dose of RSVPreF3 non-adjuvanted vaccine, or placebo, 2 months apart. Following favorable safety evaluation, a staggered enrolment with 2 steps followed in OA aged 60–80 years, who were randomized 1:1:1:1:1:1:1:1:1:1 to receive 1 of the 9 RSV vaccine formulations containing Low-, Medium- or High-dose of RSVPreF3 non-adjuvanted or adjuvanted with AS01E or AS01B, or placebo (same schedule). Safety/reactogenicity up to 1 month post-dose 1 are reported here.ResultsExposed set was comprised of 48 YA and 1005 OA. Within 7 days post-dose 1, any solicited/unsolicited adverse event (AE) ranged from 58.3% to 83.3% across YA vaccinees (placebo YA: 58.3%) and from 29.9% to 84.2% across OA vaccinees (placebo OA: 33.7%) (Fig 1). Pain was the most common solicited local AE, being reported in ≤ 58.3% of YA (placebo YA: 0.0%) and at higher rates in the adjuvanted groups (≤ 75.7%) vs non-adjuvanted groups of OA (≤ 14.1%) and placebo OA (4.1%) (Fig 2A). Of solicited general AEs, fatigue (YA: ≤ 41.7% in vaccinees vs 50.0% in placebo; OA: ≤ 48.5% in vaccinees vs 16.3% in placebo) and headache (YA: ≤ 33.3% in vaccinees vs 16.7% in placebo; OA: ≤ 27.7% in vaccinees vs 8.2% in placebo) were most commonly reported (Fig 2B), while fever ≥ 38.0 °C was observed in ≤ 3.0% of OA vaccinees (placebo OA: 0.0%). Grade 3 solicited local and general AEs were observed in OA only, with erythema (≤ 4.9% in vaccinees vs 0.0% in placebo) and fatigue (≤ 2.0% in vaccinees vs 1.0% in placebo) being most common (Fig 2). No serious AEs (SAEs) were reported in YA. A number of 11 OA reported a SAE within 1 month post-dose 1, but none was fatal or assessed as vaccine-related. No clinically significant abnormalities occurred in hematological/biochemical parameters in any group.Figure 1. Percentage of participants presenting at least one type of solicited/unsolicited adverse event (AE) within 7 days post-dose 1 Figure 2. Percentage of participants with at least one type of solicited adverse event (AE) within 7 days post-dose 1 ConclusionFirst dose of RSVPreF3 candidate vaccine is well tolerated. AE rates tended to be higher after AS01B-adjuvanted formulations compared to other vaccine formulations. No safety concerns were raised.FundingGlaxoSmithKline Biologicals SADisclosuresJelena Tica, PhD, GSK group of companies (Employee, Shareholder) Javier Ruiz Guiñazú, MD MSc, GSK group of companies (Employee, Shareholder) Charles P. Andrews, MD, GSK group of companies (Scientific Research Study Investigator) Charles Fogarty, MD, GSK group of companies (Grant/Research Support) Edward Kerwin, MD, Amphastar (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)AstraZeneca (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Boehringer Ingelheim (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Chiesi (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Cipla (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)GSK group of companies (Employee, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Mylan (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Novartis (Employee, Advisor or Review Panel member, Research Grant or Support, Speaker’s Bureau)other around 40 pharmaceutical companies (Other Financial or Material Support, conducted multicenter clinical research trials)Pearl (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Sunovion (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau)Theravance (Consultant, Scientific Research Study Investigator, Advisor or Review Panel member, Speaker’s Bureau) Isabel Leroux-Roels, MD PhD, GSK group of companies (Scientific Research Study Investigator) Corinne Vandermeulen, MD PhD, GSK group of companies (Other Financial or Material Support, My university only received Grant/Research Support) Marie-Pierre David, MSc, GSK group of companies (Employee, Shareholder) Nancy Dezutter, PhD, PharmD, RPh, GSK group of companies (Employee, Shareholder) Laurence Fissette, MSc, GSK group of companies (Employee) Juliane Koch, MD, GSK group of companies (Employee, Shareholder) Narcisa Mesaros, MD, MSc, GSK group of companies (Employee)

A Survey of Vaccine-Induced Measles IgG Antibody Titer to Verify Temporal Changes in Response to Measles Vaccination in Young Adults.

In Japan, sporadic measles cases increased rapidly in 2019 compared to the past six years. To clarify the persistence of immunity against measles in young adults, this study explored the persistence of immunoglobulin G (IgG) antibody titers against the measles virus in 17- to 24-year-old young participants who reside in the Chiba prefecture of Japan. Measles-specific IgG antibody titers, determined by enzyme immunoassay in serum samples collected from 506 participants, were assessed through statistical analyses. Multivariable regression analysis revealed that the distribution of measles IgG antibody titers was significantly correlated with a medical history of measles (P < 0.05), while there was no significant correlation between the number of vaccinations related to measles IgG titers. Furthermore, measles IgG titers tended to decrease, as revealed by the temporal change in IgG titers, during the elapsed period after the last vaccination (P = 0.08). These results indicate that periodic vaccination against measles is required to prevent sporadic measles infection in young and older adults.

A Study to Describe the Safety Profile and Compare the Immune Response of 4 Differents Formulations of an Investigational Tdap Vaccine When Compared to Licensed Tdap Vaccine in Young Adults in Canada

A Study to Describe the Safety Profile and Compare the Immune Response of 4 Differents Formulations of an Investigational Tdap Vaccine When Compared to Licensed Tdap Vaccine in Young Adults in Canada

Rubella virus neutralizing antibody response after a third dose of measles-mumps-rubella vaccine in young adults

BackgroundThird doses of measles-mumps-rubella (MMR) vaccine have been administered during mumps outbreaks and in various non-outbreak settings. The immunogenicity of the rubella component has not been evaluated following receipt of a third dose of MMR vaccine. MethodsYoung adults aged 18–31 years with documented two doses of MMR vaccine received a third dose of MMR vaccine between July 2009 and October 2010. Rubella neutralizing antibody titers were assessed before, 1 month, and 1 year after receipt of a third dose of MMR vaccine. ResultsAmong 679 participants, 1.8% had rubella antibody titers less than 10 U/ml, immediately before vaccination, approximately 15 years after receipt of a second dose of MMR vaccine. One month after receipt of a third dose of MMR vaccine, average titers were 4.5 times higher and >50% of participants had a 4-fold boost. Response was highest among those with titers less than 10 U/ml prior to vaccination (geometric mean titer ratio = 18.8; 92% seroconversion) and decreased with increasing pre-vaccination titers. Average titers declined 1 year postvaccination but remained significantly higher than pre-vaccination levels. The proportion classified as low-positive antibody levels increased from 3% 1 month postvaccination to 24% 1 year postvaccination. ConclusionsVaccination with a third dose of MMR vaccine resulted in a robust boosting of rubella neutralizing antibody response that remained elevated 1 year later. Young adults with low rubella titers are more likely to benefit from a third dose of MMR vaccine.

Marked increase in measles vaccination coverage among young adults in Switzerland: a campaign or cohort effect?

ObjectivesTo evaluate the impact of the Swiss measles elimination strategy—including a mass media campaign—on vaccination coverage and awareness among young adults aged 20–29 years.MethodsComparison of the results of two cross-sectional population surveys in 2012 and 2015.ResultsDocumented vaccination coverage increased from 77 to 88% for two doses of measles vaccine. Major determinants of complete vaccination were survey year, birth cohort, sex and the absence of prior measles disease. If birth cohort and prior history of measles disease are included as factors in a multivariate model, the difference between 2012 and 2015 vanishes.ConclusionsThe marked increase in complete measles vaccination coverage is due to a cohort effect, owing to the introduction of the second dose of vaccine in 1996. Most of the vaccinations were administered before the national strategy was implemented and vaccination catch-ups did not increase during the campaign in young adults. Nevertheless, this study provides evidence of an improvement in the awareness of measles and measles vaccination in young adults, which may result in an impact on measles vaccination coverage in the near future.

Seroepidemiological Studies on Pertussis, Diphtheria and Tetanus among Nursing Students Enrolled between 1994 and 2011 in the Kitakyushu District

Seroepidemiological studies on pertussis, diphtheria and tetanus were performed on 1,540 nursing students enrolled in S-university between 1994 and 2011. Antibody titers against pertussis toxin (PT) and filamentous hemagglutinin (FHA), diphtheria antitoxin titer, and tetanus antitoxin titer were measured using sera taken during enrollment. The antibody-seropositive rates and geometric mean titers (GMTs) were calculated by according to birth year (1975-1993). The pertussis anti-PT and anti-FHA antibody-seropositive rates (seropositive levels were both defined as ≥10 EU/mL) were 12%-53% and 47%-84%, respectively. The anti-PT antibody-seropositive rate was lower than the anti-FHA rate. The anti-PT antibody GMTs were 2.0-11 EU/mL, whereas the anti-FHA antibody GMTs were 10 EU/mL or more (8.8-31 EU/mL) in almost every group. The diphtheria antitoxin-seropositive rate (≥0.1 IU/mL) was 49%-79%, and the GMT was nearly 0.1 IU/mL. The tetanus antitoxin-seropositive rate (≥0.01 IU/mL) was 91%-100%, and the GMT was 0.3 IU/mL or more for all the groups. While the nursing students' diphtheria and tetanus antitoxin levels were sufficient to prevent both diseases, the anti-PT antibody-seropositive rate and the GMT were both lower than the level required to prevent pertussis, suggesting that many of the nursing students were pertussis-susceptible. These findings suggest a need for pertussis vaccination in young adults or early adolescents.

Pertussis specific cell-mediated immune responses ten years after acellular pertussis booster vaccination in young adults

BackgroundOne of the reasons for pertussis resurgence is waning immunity. Both humoral and cell mediated immunity (CMI) are essential for protection. The aim of this study was to evaluate CMI responses after acellular pertussis vaccination in young adults. MethodsFifty-seven young adults were followed for ten years after a diphtheria-tetanus acellular pertussis (dTpa) booster vaccination. A second booster was administrated at year 10. CMI was determined from peripheral blood mononuclear cells (PBMC) stimulated with vaccine antigens pertussis toxin (PT), filamentous hemagglutinin (FHA) and pertactin (PRN) before and one month after the second vaccination, using proliferation and IFN-γ and IL-17 ELISpot. In addition, the response to ten selected cytokines was measured from 14 subjects. ResultsBefore the booster dose, positive proliferation was recognized in 51%, 53% and 89% of the subjects against PT, PRN and FHA, respectively. One month after, the positivity rate increased to 81%, 81% and 96%. Although the number of IFN-γ and IL-17 secreting cells was increased, the expression of most of the tested cytokines was found to be downregulated. After PT stimulation, only one (7.1%) subject had increased production in all cytokines, whereas six (42.9%) had decreased production of all cytokines. Ten subjects (71.4%) had decreased concentration of IFN-γ, the cytokine important for pertussis protection. ConclusionsCMI persists even when antibodies have decayed, and acellular pertussis vaccine enhances the CMI response. Further studies are needed to illustrate what factors cause the low production of some important cytokines.

Measles Virus Neutralizing Antibody Response, Cell-Mediated Immunity, and Immunoglobulin G Antibody Avidity Before and After Receipt of a Third Dose of Measles, Mumps, and Rubella Vaccine in Young Adults.

Two doses of measles, mumps, and rubella (MMR) vaccine are 97% effective against measles, but waning antibody immunity to measles and failure of the 2-dose vaccine occur. We administered a third MMR dose (MMR3) to young adults and assessed immunogenicity over 1 year. Measles virus (MeV) neutralizing antibody concentrations, cell-mediated immunity (CMI), and immunoglobulin G (IgG) antibody avidity were assessed at baseline and 1 month and 1 year after MMR3 receipt. Of 662 subjects at baseline, 1 (0.2%) was seronegative for MeV-neutralizing antibodies (level, <8 mIU/mL), and 23 (3.5%) had low antibody levels (8-120 mIU/mL). One month after MMR3 receipt, 1 subject (0.2%) was seronegative, and 6 (0.9%) had low neutralizing antibodies, with only 21 of 662 (3.2%) showing a ≥ 4-fold rise in neutralizing antibodies. One year after MMR3 receipt, no subject was seronegative, and 10 of 617 (1.6%) had low neutralizing antibody levels. CMI analyses showed low levels of spot-forming cells after stimulation, suggesting the presence of T-cell memory, but the response was minimal after MMR3 receipt. MeV IgG avidity did not correlate with findings of neutralization analyses. Most subjects were seropositive before MMR3 receipt, and very few had a secondary immune response after MMR3 receipt. Similarly, CMI and avidity analyses showed minimal qualitative improvements in immune response after MMR3 receipt. We did not find compelling data to support a routine third dose of MMR vaccine.