A worldwide overview for hexavalent vaccines and a glimpse into Turkiye's perspective.

The surge in recommended vaccinations for child's has spurred the development of combination vaccines, notably hexavalent vaccines, which provide multiple immunizations in a single dose. These vaccines offer various advantages, such as streamlining vaccination schedules, minimizing injection-related pain and exposure to preservatives, expanding vaccine coverage, and reducing administration costs. However, the intricate and expensive development of these vaccines presents substantial challenges, requiring increased investment and healthcare provider education to optimize their utilization and sustain high vaccination rates. Turkey, known for its robust vaccine coverage, strategic geographic location, and the influx of refugees, is at a critical juncture for integrating hexavalent vaccines into national programs. This transition is especially relevant given the rising vaccine hesitancy and the potential resurgence of vaccine-preventable diseases. This review assesses the deployment of hexavalent vaccines, examining their benefits and challenges through clinical trials and global experiences, with a specific emphasis on Turkiye's public health context.

The Present and Future Aspects of Life-Long Pertussis Prevention: Narrative Review with Regional Perspectives for Türkiye.

Pertussis, caused by Bordetella pertussis, remains one of the most widespread, contagious, and vaccine-preventable diseases. It results in notable morbidity and mortality as well as severe medical, social, and economic burden. Despite high global vaccine coverage, pertussis continues to be a significant epidemiologic problem, with outbreak episodes every few years just as in the pre-vaccination era. In Türkiye, there is a lack of comprehensive data on the current burden of pertussis in different age and risk groups, leading to underdiagnosis and underreporting of the disease, especially in adults who are often not considered at risk. Available data from Türkiye also reveal inadequate levels of protective antibodies in preterm newborns, emphasizing the need for additional preventive measures. Authors stated that improving physician awareness of pertussis symptoms in patients with prolonged cough, increasing access to routine pertussis tests, and conducting surveillance studies would aid in accurate diagnosis and reporting in Türkiye. As the Turkish Ministry of Health Antenatal Care Management Guide suggests routine second and third pregnancy check-up visits at weeks 18-24 and 28-32 correspondingly, this period can be considered the ideal vaccination time for Türkiye. Introducing a booster dose of Tdap at around 10 years of age or during national military service would reduce transmission and protect susceptible individuals. Identifying individuals at high risk of severe pertussis and prioritizing them for a booster dose is also crucial in Türkiye. Enhancing surveillance systems, increasing healthcare professionals' awareness through training, and organizing catch-up visits for missed vaccinations during the COVID-19 pandemic are mentioned as additional strategies to improve pertussis prevention in Türkiye. This review focuses on the global and regional burden of pertussis and obstacles to effective prevention and evaluates existing strategies to achieve lifelong pertussis prevention. Literature and current strategies were also discussed from a Turkish national standpoint.

Influenza vaccination situation in Middle-East and North Africa countries: Report of the 7th MENA Influenza Stakeholders Network (MENA-ISN).

BACKGROUND: The Middle East and North Africa (MENA) region faces a dual challenge with regard to influenza infection due to severe zoonotic influenza outbreaks episodes and the circulation of Northern Hemisphere human influenza viruses among pilgrims. METHODS: The MENA Influenza Stakeholder Network (MENA-ISN) was set-up with the aim of increasing seasonal influenza vaccination coverage by (i) enhancing evidence-based exchanges, and (ii) increasing awareness on the safety and benefits of seasonal vaccination. During the 7th MENA-ISN meeting, representatives from 8 countries presented their influenza surveillance, vaccination coverage and actions achieved and provided a list of country objectives for the upcoming 3 years. RESULTS: MENA-ISN countries share the goal to reduce influenza related morbidity and mortality. Participants admitted that lack of knowledge about influenza, its consequences in terms of morbidity, mortality and economy are the major barrier to attaining higher influenza vaccination coverage in their countries. The cost of the vaccine is another key barrier that could contribute to low vaccination coverage. Participants drew a list of strategic interventions to bridge gaps in the knowledge of influenza burden in this region. CONCLUSIONS: Participating countries concluded that despite an increase in vaccine uptake observed during the last few years, influenza vaccination coverage remains relatively low. Priority areas should be identified and action plans tailored to each country situation set-up to investigate the best way to move forward.

Interchangeability of a hepatitis A vaccine second dose: Avaxim 80 following a first dose of Vaqta 25 or Havrix 720 in children in Turkey.

INTRODUCTION: This randomised, observer-blind clinical trial conducted in Turkey evaluated the immunogenicity, safety and interchangeability of three paediatric inactivated hepatitis A vaccines in 424 seronegative children between 1 and 15 years of age. METHODS: Potential subjects were screened for anti-hepatitis A virus (HAV) antibodies prior to receiving a first dose of Avaxim 80, Havrix 720 or Vaqta 25, followed by a second dose of either the same vaccine or Avaxim 6 months later. Anti-HAV antibody concentrations were measured 2 weeks after the first injection, at 24 weeks (before the second dose) and at 28 weeks for the evaluation of the immune response. RESULTS: Nearly 80% of the children between 1 and 5 years of age and half of those between the ages of 6 and 10 in the population from which the subjects were recruited were seronegative for HAV antibodies. Two weeks after the first dose, 98.2% of all subjects had anti-HAV antibody concentrations equal to or higher than 20 mIU/mL, believed to be seroprotective, and all subjects were seroprotected before and after the second dose. Anti-HAV geometric mean concentrations (GMCs) 2 weeks after the first dose and before the second were similar in children who received Avaxim and Vaqta (P = 0.2), but both were higher than Havrix (P < 0.01). There were no significant differences in the anti-HAV GMCs between the study groups that received two doses of the same vaccine compared with two doses of different vaccines. There were no significant differences in the frequency of any local or systemic adverse events among the study groups following either of the two doses. CONCLUSION: All three vaccines are safe and highly immunogenic in healthy children aged 1 to 15 years. Avaxim 80 may also be given as the second dose when Havrix 720 or Vaqta 25 are given as the first dose. The pattern of seroprevalence seen here is similar to that reported in a number of recent evaluations in Turkey, and are supportive of the routine hepatitis A vaccination of young children.

Outbreak of measles in medical students and determination of immune status to measles-mumps-rubella viruses.

We conducted an investigation after a measles outbreak in medical students to determine the immunity of the medical students, the correlation between history and seropositivity, and measles-mumps-rubella vaccine effectiveness. After a preliminary study done during measles outbreak, a cross-sectional study was planned. Serum samples from 322 medical students were tested by enzyme-linked immunosorbent assay, vaccinated volunteers, then re-tested vaccinees. Histories of measles, mumps and rubella were taken. Of 322 students, seven students (2.2%) were seronegative to measles, 13 (4.0%) to mumps, and 13 (4.0%) to rubella. Historical information revealed 30.4% of sensitivity in measles and 34.3% in mumps, whereas 5.2% in rubella. Among those seronegative on admission and vaccinated, seroconversion rates were 100% (5/5), 90.9% (10/11), 100% (8/8) in measles, mumps and rubella vaccine, respectively. Of 265 vaccinated students parotitis was detected in one female student, arthralgia was observed in three students (1.1%) and myalgia in two (0.7%), and 240 students reported no side effects. We detected the unreliable historical screening and high seroprevalence of measles, mumps and rubella in prevaccine era for mumps and rubella and, safety of MMR vaccination in medical students in Turkey.

Assessment of the antibody response in 110 healthy individuals who have been subject to Vi capsular polysaccharide vaccine.

Typhoid fever is a disease predominant in underdeveloped and developing countries. Typhoid fever is more prevalent, in fact endemic, in countries where fecal contamination of water and food sources are very common. The majority of the reported cases are in the adult age group. There are three different vaccines which can be used to prevent typhoid fever. In this study, we have used the parenteral Vi vaccine which was developed using the polysaccharide Vi antigen that covers the bacterial surface, thus, concealing the O antigen protecting the bacteria against Anti-O antibodies and regarded as virulence factor. A total of 110 individuals whose sera were negative for seroconversion prior to vaccination were included in this study in which we have assessed Anti-Vi antibodies by tube agglutination. Serum and stool samples of 110 individuals were assessed 1 month after the vaccination. A total of 105 (95.5%) of the vaccinated people were considered to have positive (1/40 and higher) response and this result was regarded as prophylactic seroconversion. None of the people in the study group had Salmonella typhi, S. paratyphi A,B,C isolated from their stool cultures.