Search

Pneumococcal disease affects people across all ages but is more prevalent in young children and the elderly. Despite the availability of the pneumococcal vaccine for adults, the disease burden and mortality associated with it remains a challenge. A few studies conducted in Lebanon have reported epidemiology of pneumococcal disease, concurring the high burden among adults and older adults in the region. The pneumococcal vaccine is a part of the routine immunization schedule for children, but there are no recommendations for adult vaccination. A medical advisory board was hence conducted in September 2020 to discuss the burden of pneumococcal disease (PD) among adults in Lebanon. The participants were experts from the fields of internal medicine, family medicine, hematology, cardiology, oncology, endocrinology, pulmonology, and infectious diseases. The experts reached a consensus that there is a need to take steps to increase the rate of adult vaccination uptake and create awareness among physicians, pharmacists, caregivers, and patients. The physicians should be trained on adult immunization and should actively discuss the importance of the pneumococcal vaccine, especially with high-risk adult patients. Implementing adult vaccination as a routine practice and involving various stakeholders to address the gaps can help in reducing the burden of pneumococcal disease in adults.

In this study involving a cohort of employees of the National Airline company in Lebanon, we assessed humoral immunity levels and the effectiveness of two COVID-19 vaccines, Gam-COVID-Vac versus BNT162b2, after two doses and after a homologous and heterologous BNT162b2 booster, in addition to the impact of hybrid immunity. Vaccine effectiveness (VE) was retrospectively determined against laboratory-confirmed SARS-CoV-2 infection during the periods of Delta and Omicron variants’ predominance, separately, and was calculated based on a case–control study design. The humoral immune response, measured by a SARS-CoV-2 anti-spike receptor-binding domain (RBD) IgG titer, was prospectively assessed after the aforementioned vaccination schemes at different time points. This study showed higher effectiveness of BNT162b2 after two doses (81%) compared to two doses of Gam-COVID-Vac (41.8%) against the Delta variant of SARS-CoV-2, which correlated with anti-spike antibody levels. Regarding the Omicron variant, protection against infection and antibody levels were severely compromised and the correlation between an anti-spike IgG titer and effectiveness was lost, unlike the situation during the Delta wave. Considering the booster vaccination schemes, a homologous BNT162b2 booster after a BNT162b2 primary vaccination induced a higher humoral immune response when compared to that induced by a heterologous BNT162b2 booster after a Gam-COVID-Vac primary vaccination. However, the VE of both booster regimens against the Omicron variant was almost equal (64% in the homologous regimen and 57% in heterologous regimen). Hybrid immunity evidenced a better humoral response and a greater and longer protection against Delta and Omicron infections compared to vaccination-induced immunity in COVID-19-naïve individuals. Finally, the findings show that VE waned with time during the same wave, highlighting the importance of reinforcing primary and booster COVID-19 vaccination mainly at the beginning of each wave during the surge of a new variant of concern.