Investigating the Antibody Imprinting Hypothesis among Canadian Paramedics after SARS-CoV-2 Omicron Variant Circulation.

Recent research has highlighted the Omicron variant's capacity to evade immune protection conferred by wild-type (WT) mRNA vaccines. Despite this observation, the potential involvement of antigenic sin phenomena remains unclear. Our hypothesis posited that a greater number of prior WT vaccine doses might lead to reduced anti-Omicron neutralization Abs following Omicron infection. To investigate this, we analyzed blood samples from human participants in the COVID-19 Occupational Risk, Seroprevalence, and Immunity among Paramedics (CORSIP) study who had received at least one WT mRNA vaccine before contracting Omicron. The exposure variable was the number of WT mRNA vaccines administered, and the outcome was the angiotensin-converting enzyme 2 (ACE-2) percent inhibition specific to the BA.4/BA.5 Omicron Ag. Contrary to expectations, our findings revealed that more WT-based vaccines were associated with an enhanced Omicron-specific immune response.

The protective effect of pneumococcal vaccination on cardiovascular disease in adults: A systematic review and meta-analysis.

BACKGROUND: Epidemiological studies suggest that there is a link between pneumococcal infection and adverse cardiovascular outcomes such as myocardial infarction. Multiple studies have evaluated the protective effect of the 23-valent polysaccharide pneumococcal vaccination (PPV23), but results have varied. Therefore, a meta-analysis was conducted to summarize available evidence on the impact of PPV23 on cardiovascular disease. METHODS: A literature search from January 1946 to September 2019 was conducted across Embase, Medline and Cochrane. All studies were included that evaluated PPV23 compared with a control (placebo, no vaccine or another vaccine) for any cardiovascular events, including: myocardial infarction (MI), heart failure and cerebrovascular events. Risk ratios (RRs) were pooled using random effects models. RESULTS: Eighteen studies were included, with a total of 716,108 participants. Vaccination with PPV23 was associated with decreased risk of any cardiovascular event (RR: 0.91; 95% CI: 0.84-0.99), and MI (RR: 0.88; 95% CI: 0.79-0.98) in all age groups, with a significant effect in those aged ≥65 years, but not in the younger age group. Similarly, PPV23 vaccine was associated with significant risk reduction in all-cause mortality in all ages (RR: 0.78; 95% CI: 0.68-0.88), specifically in those aged ≥65 years (RR: 0.71; 95% CI: 0.60-0.84). A significant risk reduction in cerebrovascular disease was not observed following pneumococcal vaccination. CONCLUSIONS: Polysaccharide pneumococcal vaccination decreased the risk for some adverse cardiovascular events, specifically acute MI in the vaccinated population, particularly for those individuals aged ≥65 years. It would be highly beneficial to vaccinate the population who is at greater risk of cardiovascular diseases.