BACKGROUND: Vaccination of healthcare workers (HCWs) is pivotal in decreasing the incidence of contagious infections in hospital settings. In this study, we assessed the knowledge, attitude, and practice regarding HCWs\' recommended vaccines among medical students and interns in Egypt.
METHODS: A multicenter, cross-sectional study was conducted using a structured, pilot-tested, and self-administered questionnaire among Egyptian medical students and interns. We invited 1332 participants to our survey using a systematic random sampling that included participants across nine medical schools in Egypt during the 2021-2022 academic year.
RESULTS: Out of 1332 participants, 1141 completed our questionnaire with a response rate of 85.7%. Overall, 43% of the participants had intermediate knowledge (knew 2-3 HCWs\' recommended vaccines). Furthermore, 36.7% had received a booster dose of at least one of the HCWs\' recommended vaccines over the last 10 years, with only 6.1% having received all recommended vaccines. Hepatitis B vaccine was the most widely known (71%) and received (66.7%). Interns were more likely to know, receive, and recommend HCWs\' recommended vaccines. The majority (> 90%) agreed that vaccination is beneficial and safe, with a median score of eight (interquartile range [IQR: Q25-Q75]: 7-9) out of ten for vaccine efficacy and eight (IQR: 7-8) for safety. However, the median score for hesitancy was five (IQR: 2-7). The most common influential and limiting factors for vaccination were scientific facts (60.1%) and fear of vaccine side effects (44.9%).
CONCLUSIONS: Although medical students in Egypt have good knowledge of and attitudes towards vaccination, there is a gap in their practices. Interventions are needed to improve vaccination uptake among medical students in Egypt.

OBJECTIVE: The National Vaccination Plan against SARS-CoV-2/COVID-19 was launched by the Ministry of Health and Social Protection, on 14 February 2021. The main objective of the study was to evaluate the effectiveness of the Corona Vac in preventing three clinical outcomes defined as Infection, Hospitalisation or Death, in a real-world scenario.
METHODS: This is a population-based retrospective dynamic cohort study using a multivariate Cox model to calculate Hazard Ratios (HR) for estimate of vaccine effectiveness, starting on 17 Feb 2021 up to 30 June 2022. The data were taken from the surveillance systems for 12 months for each individual. Four cities were selected considering that each one had a reliable data base.
RESULTS: Corona Vac effectiveness was estimated in 32% (95% CI 31-33) in preventing infection, 55% (95%CI 54-56) in hospitalisation, and 90% (95%CI 89-90) in death, at the end of the follow-up. These findings were more consistent during the four first months. Comparing with unvaccinated, booster homologous doses did appear to increase effectiveness in preventing hospitalisation, but for booster heterologous increase protection for hospitalisation and death. Booster doses to whom already were vaccinated with CoronaVac did not improve its effectiveness neither when they received heterologous boosters.
CONCLUSIONS: CoronaVac shows effectiveness in preventing death or hospitalisation during the first year of follow-up, but less in preventing infection, decreasing rapidly after the first four months of follow-up. It was higher in children between 3 and 12 years, as well as in those over 60. Boosters\' doses did not improved effectiveness in those CoronaVac already vaccinated.

Participants in studies investigating COVID-19 vaccines commonly report reactogenicity events, and concerns about side effects may lead to a reluctance to receive updated COVID-19 vaccinations. A real-world, post hoc analysis, observational 2019nCoV-406 study was conducted to examine reactogenicity within the first 2 days after vaccination with either a protein-based vaccine (NVX-CoV2373) or an mRNA vaccine (BNT162b2 or mRNA-1273) in individuals who previously completed a primary series. Propensity score adjustments were conducted to address potential confounding. The analysis included 1130 participants who received a booster dose of NVX-CoV2373 (n = 303) or an mRNA vaccine (n = 827) during the study period. Within the first 2 days after vaccination, solicited systemic reactogenicity events (adjusted) were reported in 60.5% of participants who received NVX-CoV2373 compared with 84.3% of participants who received an mRNA vaccine; moreover, 33.9% and 61.4%, respectively, reported ≥3 systemic reactogenicity symptoms. The adjusted mean (95% CI) number of systemic symptoms was 1.8 (1.6-2.0) and 3.2 (3.0-3.4), respectively. Local reactogenicity events (adjusted) were reported in 73.4% and 91.7% of participants who received NVX-CoV2373 and mRNA vaccines, respectively; the adjusted mean (95% CI) number of local symptoms was 1.5 (1.33-1.61) and 2.4 (2.31-2.52), respectively. These results support the use of adjuvanted, protein-based NVX-CoV2373 as an immunization option with lower reactogenicity than mRNAs.

We report neutralization titer data against contemporary SARS-CoV-2 sublineages from an ongoing, phase 2/3, open-label, clinical trial of a single dose (30 μg) of an Omicron XBB.1.5-adapted BNT162b2 monovalent mRNA vaccine. The trial included healthy participants who had received at least three previous doses of an mRNA vaccine authorized in the United States, with the most recent authorized vaccine dose being a bivalent Omicron BA.4/BA.5-adapted vaccine given at least 150 days before the study vaccination. In this analysis, Omicron XBB.1.5, BA.2.86, and JN.1 serum neutralizing titers were assessed at baseline and at 1 month after vaccination. Analyses were conducted in a subset of participants who were at least 18 years of age (N = 40) and who had evidence of previous SARS-CoV-2 infection. Immunogenicity was also evaluated in a group of participants who received bivalent BA.4/BA.5-adapted BNT162b2 in another study (ClinicalTrials.gov Identifier: NCT05472038) and who were matched demographically to the participants in the current trial. In this analysis, monovalent XBB.1.5-adapted BNT162b2 vaccine elicited higher XBB.1.5, BA.2.86, and JN.1 neutralizing titers than those elicited by bivalent BA.4/BA.5-adapted BNT162b2. Overall geometric mean fold rises in neutralizing titers from baseline to 1 month after vaccination were higher among participants who received XBB.1.5-adapted BNT162b2 than those who received bivalent BA.4/BA.5-adapted BNT162b2 for XBB.1.5 (7.6 vs. 5.6), slightly higher for JN.1 (3.9 vs. 3.5), and similar for BA.2.86 (4.8 vs. 4.9). ClinicalTrials.gov Identifier: NCT05997290.

BACKGROUND: To compare the real-world effectiveness of a third dose of mRNA-1273 versus a third dose of BNT162b2 against breakthrough COVID-19 hospitalizations among adults aged ≥ 65 years who completed a primary series of an mRNA-based COVID-19 vaccine (regardless of which primary series was received).
METHODS: This observational comparative vaccine effectiveness (VE) study was conducted using administrative claims data from the US HealthVerity database (September 22, 2021, to August 31, 2022). A third dose of mRNA-1273 versus BNT162b2 was assessed for preventing COVID-19 hospitalizations and medically attended COVID-19 among adults aged ≥ 65 years. Inverse probability of treatment weighting was applied to balance baseline characteristics between vaccine groups. Incidence rates from patient-level data and hazard ratios (HRs) with 95 % confidence intervals (CIs) using weighted Cox proportional hazards models were calculated to estimate relative VE for each outcome.
RESULTS: Overall, 94,587 and 92,377 individuals received a third dose of mRNA-1273 and BNT162b2, respectively. Among the weighted population, the median age was 69 years (interquartile range, 66-74), 53 % were female, and 46 % were commercially insured. COVID-19 hospitalization rates per 1000 person-years (PYs) were 5.61 (95 % CI, 5.13-6.09) for mRNA-1273 and 7.06 (95 % CI, 6.54-7.57) for BNT162b2 (HR, 0.82; 0.69-0.98). Medically attended COVID-19 rates per 1000 PYs (95 % CI) were 95.05 (95 % CI, 93.03-97.06) for mRNA-1273 and 106.55 (95 % CI, 104.53-108.57) for BNT162b2 (HR, 0.93; 0.89-0.98).
CONCLUSIONS: Results from this observational comparative VE database study provide evidence that among older adults, a third dose of mRNA-1273 was more effective in preventing breakthrough COVID-19 hospitalization and medically attended COVID-19 infection compared with a third dose of BNT162b2.

The BOOST (Booster promotion for older outpatients using SMS text reminders) program at Taipei Veterans General Hospital assessed the effectiveness of text message reminders in enhancing COVID-19 booster vaccination rates among the elderly, guided by the Health Belief Model (HBM). Targeting patients aged 65 and above, eligible yet unvaccinated for a COVID-19 booster, this cohort study sent personalized reminders a week prior to their scheduled appointments between April 18, 2022, and May 12, 2022, acting as cues to action to enhance vaccination uptake by overcoming perceived barriers and raising awareness of benefits. Over 5 weeks, the study observed a 38% increase in vaccination rate among 3,500 eligible patients, markedly surpassing the concurrent national rate increase of 4% for the same demographic. The majority of vaccinations occurred within two weeks after the reminder, illustrating the effectiveness of the strategy. Cox regression analysis identified age and time since last vaccination as significant predictors of responsiveness, with those aged 65-74 and 75-84 showing higher uptake, particularly when reminders were sent within 4 months after the last dose. A single reminder proved to be effective. The findings of this study demonstrate the potential of SMS reminders to promote COVID-19 vaccination among the elderly through the strategic use of HBM principles, suggesting a feasible and effective approach to public health communication.

UNASSIGNED: Coronavirus disease 2019 (COVID-19) has become a global pandemic and led to increased mortality and morbidity. Vaccines against the etiologic agent; severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) were approved for emergency use on different platforms. In the early phase of the pandemic, Thai healthcare workers (HCWs) received CoronaVac, an inactivated vaccine, as the first vaccine against SARS-CoV-2, followed by ChAdOx1 nCoV-19, a viral vector-based vaccine, or BNT162b2, an mRNA vaccine, as a booster dose. This preliminary study evaluated the immunogenicity of ChAdOx1 nCoV-19 and BNT162b2 as a booster dose in HCWs who previously received two doses of CoronaVac.
UNASSIGNED: Ten HCW participants received ChAdOx1 nCoV-19 and another 10 HCWs received BNT162b2 as a booster dose after two doses of CoronaVac. Anti-RBD IgG, neutralizing antibodies (NAb), and cellular immunity, including interferon-gamma (IFN-γ)-releasing CD4, CD8, double negative T cells, and NK cells, were measured at 3 and 5 months after the booster dose.
UNASSIGNED: There was no significant difference in anti-RBD IgG levels at 3 and 5 months between the two different types of booster vaccine. The levels of anti-RBD IgG and NAb were significantly decreased at 5 months. HCWs receiving BNT162b2 had significantly higher NAb levels than those receiving ChAdOx1 nCoV-19 at 5 months after the booster dose. IFN-γ release from CD4 T cells was detected at 3 months with no significant difference between the two types of booster vaccines. However, IFN-γ-releasing CD4 T cells were present at 5 months in the ChAdOx1 nCoV-19 group only.
UNASSIGNED: ChAdOx1 nCoV-19 or BNT162b2 can be used as a booster dose after completion of the primary series primed by inactivated vaccine. Although the levels of immunity decline at 5 months, they may be adequate during the first 3 months after the booster dose.

Suspected allergic reactions after mRNA COVID-19 vaccination withheld multiple individuals from getting fully vaccinated during the pandemic. We vaccinated adults who had experienced possible allergic symptoms after their first intramuscular dose of a COVID-19 mRNA vaccine with a 1/5th fractional intradermal test dose of the mRNA-1273 (Moderna) COVID-19 vaccine. No anaphylactic reactions were observed after intradermal vaccination (n = 56). Serum anti-S1 IgG concentrations were measured using a bead-based multiplex assay four weeks after vaccinations. Antibody concentrations were compared with a previously collected nationwide cohort that had received two intramuscular doses of mRNA-1273. Antibody responses in all subjects tested (n = 47) were comparable to standard of care intramuscular dosing. Fractional intradermal dosing of mRNA COVID-19 vaccines may provide a pragmatic solution that is safe, time efficient compared to skin prick testing, dose sparing and immunogenic in individuals with suspected vaccine allergy.

As solid organ transplant (SOT) recipients remain at risk of severe outcomes after SARS-CoV-2 infections, vaccination continues to be an important preventive measure. In SOT recipients previously vaccinated with at least three doses of BNT162b2, we investigated humoral responses to BNT162b2 booster doses. Anti-SARS-CoV-2 receptor binding domain (RBD) immunoglobulin G (IgG) was measured using an in-house ELISA. Linear mixed models were fitted to investigate the change in the geometric mean concentration (GMC) of anti-SARS-CoV-2 RBD IgG after vaccination in participants with intervals of more or less than six months between the last two doses of vaccine. We included 107 SOT recipients vaccinated with a BNT162b2 vaccine. In participants with an interval of more than six months between the last two vaccine doses, we found a 1.34-fold change in GMC per month (95% CI 1.25-1.44), while we found a 1.09-fold change in GMC per month (95% CI 0.89-1.34) in participants with an interval of less than six months between the last two vaccine doses, resulting in a rate ratio of 0.82 (95% CI 0.66 to 1.01, p = 0.063). In conclusion, the administration of identical COVID-19 mRNA vaccine boosters within six months to SOT recipients may result in limited humoral immunogenicity of the last dose.

BACKGROUND: Data on protection afforded by updated COVID-19 vaccines (bivalent/XBB 1.5 monovalent) against the emergent JN.1 variant remains limited.
METHODS: We conducted a retrospective population-based cohort study amongst all boosted Singaporeans aged ≥18 years during a COVID-19 wave predominantly driven by JN.1, from 26th November 2023 to 13th January 2024. Multivariable Cox regression was utilised to assess risk of SARS-CoV-2 infection and COVID-19 associated emergency-department (ED) visits/hospitalizations, stratified by vaccination status/prior infection; with individuals last boosted ≥1 year utilized as the reference category. Vaccination and infection status were classified using national registries.
RESULTS: 3,086,562 boosted adult Singaporeans were included in the study population, accounting for 146,863,476 person-days of observation. During the JN.1 outbreak, 28,160 SARS-CoV-2 infections were recorded, with 2,926 hospitalizations and 3,747 ED-visits. Compared with individuals last boosted ≥1 year prior with ancestral monovalent vaccines, receipt of an updated XBB.1.5 booster 8-120 days prior was associated with lower risk of JN.1 infection (adjusted-hazard-ratio, aHR = 0.59[0.52-0.66]), COVID-19 associated ED-visits (aHR = 0.50[0.34-0.73]) and hospitalizations(aHR = 0.58[0.37-0.91]), while receipt of a bivalent booster 121-365 days prior was associated with lower risk of JN.1 infection (aHR = 0.92[0.88-0.95]) and ED-visits (aHR = 0.80[0.70-0.90]). Lower risk of COVID-19 hospitalization during the JN.1 outbreak (aHR = 0.57[0.33-0.97]) was still observed following receipt of an updated XBB.1.5 booster 8-120 days prior, even when analysis was restricted to previously infected individuals.
CONCLUSIONS: Recent receipt of updated boosters conferred protection against SARS-CoV-2 infection and ED-visits/hospitalization during a JN.1 variant wave, in both previously infected and uninfected individuals. Annual booster doses confer protection during COVID-19 endemicity.