Vaccinated and unvaccinated children — has anyone ever compared them?

Aim of the study: Measles (rubeola) is a highly contagious disease with significant morbidity and mortality. Measles-mumps-rubella (MMR) is a live-attenuated vaccine that has been used in the United States (US) since the early 1970s to prevent measles infection. This retrospective longitudinal cohort study examined the effectiveness of childhood MMR vaccination (VE) in preventing diagnosed measles cases.

Results: Members of the MMR-vaccinated cohort had a significantly lower risk of measles in the unadjusted (VE = 83.6, 95% CI = 67.2–91.8%) and adjusted (VE = 80.7, 95% CI = 61.5–83.9%) models than members of the unvaccinated cohort. VE was 80% among younger MMR recipients (12–15 months) and 90% among older MMR recipients (16–20 months), compared with the unvaccinated cohort. Routine childhood MMR vaccination significantly reduced the rate of childhood measles infections, and VE was greater in older recipients (16–20 months) than in younger recipients (12–15 months).

Aim of the study: Data on the indirect protection of children through COVID-19 vaccination of household members are insufficient, and analyses evaluating the effectiveness of COVID-19 vaccines are limited.

Results: A total of 18.4% (2289) were vaccinated: 91.4% with the BNT162b2 mRNA vaccine and 8.6% with an inactivated COVID-19 vaccine; 48.7% received one dose, and 51.3% received two doses. Real-time RT-PCR positivity rates were much higher in older children (P < 0.001) and were higher in children aged 12 years and older [odds ratio (OR), 1.34; 95% confidence interval (CI): 1.21–1.47] than in others. SARS-CoV-2 infection was significantly less common in the vaccinated group (fully and incompletely vaccinated) (P < 0.001). Unvaccinated (OR, 4.88; 95% CI: 3.77–6.13) and incompletely vaccinated children (OR, 1.83; 95% CI: 1.52–2.12) had a higher risk of COVID-19 infection than fully vaccinated patients. No significant association was found between patients’ COVID-19 real-time RT-PCR positivity rates and the vaccination status or vaccine preferences of household members (P > 0.05 for each). SARS-CoV-2 infection rates were significantly lower in vaccinated children, especially those who received mRNA vaccines.

Aim of the study: Türkiye introduced a two-dose inactivated hepatitis A vaccination program in 2012 as part of the national childhood immunization schedule. However, data on the long-term persistence of vaccine-induced immunity in Turkish children remain limited. This study aimed to evaluate the durability of anti-HAV IgG responses following routine childhood hepatitis A vaccination.

Results: Anti-HAV IgG seropositivity was 97.8% among vaccinated children. Seropositivity rates remained high over time but showed a gradual decline from 99.4% in the first year to 90.0% in the eighth year after vaccination. Despite this decrease, most vaccinated children remained seropositive throughout the follow-up period. In contrast, seropositivity was 38.7% in the unvaccinated group, reflecting natural exposure to hepatitis A virus in the population. Because of the retrospective cross-sectional design, changes in antibodies over time, clinically confirmed hepatitis A cases, and possible silent HAV infections could not be systematically evaluated. Our findings show that a two-dose inactivated hepatitis A vaccination schedule provides sustained serological protection for up to eight years in Turkish children.

Aim of the study: The WHO has recently recommended the inclusion of rotavirus vaccine in the national immunization programs of all countries. In countries in the Americas, Europe and Australia that have adopted routine childhood immunization against rotavirus, significant reductions in the burden of severe childhood diarrhea have been observed.

Results: The WHO has recently recommended the inclusion of rotavirus vaccine in the national immunization programs of all countries. In countries in the Americas, Europe and Australia that have adopted routine childhood immunization against rotavirus, significant reductions in the burden of severe childhood diarrhea have been observed. In addition to protecting vaccinated children, disease rates also appear to be lower among unvaccinated children, suggesting indirect benefits from vaccination (i.e., herd protection). Early clinical trial data from Africa and Asia are promising, and further efforts are needed to optimize the benefits of vaccination in developing countries, where vaccines are likely to have their greatest impact.

Aim of the study: Infections caused by Streptococcus pneumoniae (also known as pneumococci) pose a threat to human health. Pneumococcal infections are the most common cause of milder respiratory tract infections, such as otitis and sinusitis, and of more severe diseases, including pneumonia (with or without septicaemia) and meningitis.

Results: Thus, new approaches are needed for the treatment and prevention of pneumococcal infections, and recent advances in the field may pave the way for new strategies. Recently, several important findings have emerged regarding pneumococcal epidemiology, genomics, and the effects of the introduction of pneumococcal conjugate vaccines and the COVID-19 pandemic. Moreover, studies clarifying disease mechanisms have shown that interactions between pneumococcal virulence factors and host receptors may be used to develop new therapies, and new vaccine candidates have been suggested. In this Review, we summarize recent findings, from clinical disease to basic studies of disease mechanisms, that may be important for future control strategies.