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Given emerging evidence of immune escape in the SARS-CoV-2 Omicron viral variant, and its dominance, effectiveness of heterologous and homologous boosting schedules commonly used in low-to-middle income countries needs to be re-evaluated. We conducted a test-negative design using consolidated national administrative data in Malaysia to compare the effectiveness of homologous and heterologous BNT162b2, CoronaVac, and AZD1222 booster vaccination against SARS-CoV-2 infection in predominant-Delta and predominant-Omicron periods. Across both periods, homologous CoronaVac and AZD1222 boosting demonstrated lower effectiveness than heterologous boosting for CoronaVac and AZD1222 primary vaccination recipients and homologous BNT162b2 boosting. Broadly, marginal effectiveness was smaller by 40-50 percentage points in the Omicron period than the Delta period. Without effective and accessible second-generation vaccines, heterologous boosting using BNT162b2 for inactivated and vectored primary vaccination recipients is preferred.

In people with multiple sclerosis (PWMS), exercise improves aerobic capacity and muscle strength which are key components of physical function and overall health status. However, the effects diminish after exercise cessation. Therefore, the present study aimed to investigate whether exercise booster sessions (EBS) could preserve the exercise-induced improvements. Multicentre RCT. Ninety-four PWMS performed 12 weeks of aerobic-training (AT) or resistance-training (RT) and were subsequently randomised to receive EBS (two sessions every fifth week) (ATboost n = 24, RTboost n = 24) or usual-care (ATuc n = 20, or RTuc n = 26) for 40 weeks. The primary outcome was physical function measured as a composite score of the six-minute walk test (6MWT) and five-time sit-to-stand test (5STS). Secondary outcomes were aerobic capacity and muscle strength. No between-group difference was observed in the composite score of 6MWT and 5STS (arbitrary unit) between ATboost and RTboost 0.00 [−0.20; 0.20]. No between-group difference was observed for aerobic capacity (mL O2/kg/min) between ATboost and ATuc 1.1 [−1.9; 4.1], although a within-group change was observed for ATboost −1.9 [−4.0; 0.1], but not for ATuc −3.0 [−5.2; −0.8]. No between-group difference was seen for muscle strength (Nm/kg) between RTboost and RTuc −0.04 [−0.36; 0.28]. Also, no within-group change was observed for neither RTboost −0.07 [−0.30; 0.14] nor RTuc −0.04 [−0.27; 0.20]. EBS had no apparent effect on preservation of physical function, aerobic capacity, or muscle strength in PWMS. Muscle strength was preserved regardless of group, whereas only ATboost preserved exercise-induced improvements in aerobic capacity.

IntroductionCOVID-19 boosters restore waning immunity. After demonstrating non-inferiority of 15 μg versus 30 μg BNT162b2 at 28 days in Mongolian adults, we assessed 24-month immunogenicity and safety.MethodsIn this randomised, controlled trial, adults primed with ChAdOx1-S, BBIBP-CorV, or Gam-COVID-Vac were assigned (1:1) to 15 μg or 30 μg BNT162b2. Anti-spike IgG, surrogate virus neutralisation (sVNT) against Wuhan-Hu-1 and Omicron BA.1, and interferon-gamma (IFN-γ) release assays (Ag1/Ag2) were assessed to 24 months. SARS-CoV-2 infections and serious adverse events (SAEs) were recorded. ClinicalTrials.gov: NCT05265065.ResultsOf 601 participants, 520 (86.5%) completed follow-up. IgG and IFN-γ responses were comparable between arms at 24 months (IgG geometric mean ratio (GMR) 1.06 [95% CI 0.95–1.18]; Ag1 GMR 1.17 [95% CI 0.82–1.66]; Ag2 GMR 1.06 [95% CI 0.73–1.54]). Median sVNT inhibition remained high (Wuhan-Hu-1 88% [interquartile range (IQR) 86–90]; Omicron BA.1 85% [IQR 70–88]). Twenty-eight SARS-CoV-2 infections occurred. Fifty-three SAEs were balanced by study arm, and none were vaccine related.DiscussionEquivalent immunity and safety from 15 μg and 30 μg BNT162b2 boosters support fractional dosing as a cost-saving strategy.Clinical Trial Registrationhttps://clinicaltrials.gov/study/NCT05265065, identifier NCT05265065.

The development of COVID-19 vaccines has helped limit the extent of the pandemic, which over the past 2 years has claimed the lived of millions of people. The Moderna and Pfizer COVID-19 vaccines were the first to be manufactured using mRNA technology. Since then, other manufacturers have built their own vaccines which utilize adenovirus vector, whole inactivated coronavirus, and protein subunit methods. Given the continued mutation of the SARS-CoV-2 virus, a booster of the COVID-19 vaccine offers additional protection for citizens, especially those with comorbid conditions. However, uptake of the vaccine and booster has faced hurdles. This literature review aims to analyze the acceptance of the COVID-19 booster among different populations throughout the world. Keywords searched include “COVID-19 vaccine rates OR COVID-19 booster rates,” “COVID-19 vaccine hesitancy,” “COVID-19 booster hesitancy,” “reasons against COVID-19 vaccine,” “reasons for COVID-19 vaccine,” and “COVID-19 vaccine acceptance” (for each country). Research articles indexed in PubMed, University of Illinois Urbana-Champaign Library, and Google Scholar were included. Despite the proven effectiveness of the COVID-19 booster, vaccine hesitancy is still causing suboptimal compliance to the primary vaccine and booster, thus slowing down control of the pandemic. Reasons for vaccine hesitancy differ by country and acceptance is affected by misinformation, political circumstances, and cultural values. Among the most common reasons found are distrust in the government, a lack of safety information, and fear of side effects. Uptake of the COVID-19 vaccine has also been delayed in low and middle income countries due to resource allocation and as a result, these countries have fallen behind vaccination benchmarks. The future of COVID-19 vaccination is unknown, but vaccine mandates and additional booster doses are a possibility. Determining the ethical impact that these policies could have will allow for the best implementation.

COVID-19 vaccines are highly effective in preventing severe disease and death but are underused. Interventions to address COVID-19 vaccine hesitancy are paramount to reducing the burden of COVID-19. We aimed to evaluate the preliminary efficacy, usability, and acceptability of a chatbot for promoting COVID-19 vaccination and examine the factors associated with COVID-19 vaccine hesitancy. In November 2021, we conducted a pre-post pilot study to evaluate “Vac Chat, Fact Check,” a web-based chatbot for promoting COVID-19 vaccination. We conducted a web-based survey (N=290) on COVID-19 vaccination at a university in Hong Kong. A subset of 46 participants who were either unvaccinated (n=22) or were vaccinated but hesitant to receive boosters (n=24) were selected and given access to the chatbot for a 7-day trial period. The chatbot provided information about COVID-19 vaccination (eg, efficacy and common side effects), debunked common myths about the vaccine, and included a decision aid for selecting vaccine platforms (inactivated and mRNA vaccines). The main efficacy outcome was changes in the COVID-19 Vaccine Hesitancy Scale (VHS) score (range 9-45) from preintervention (web-based survey) to postintervention (immediately posttrial). Other efficacy outcomes included changes in intention to vaccinate or receive boosters and willingness to encourage others to vaccinate on a scale from 1 (not at all) to 5 (very). Usability was assessed by the System Usability Scale (range 0-100). Linear regression was used to examine the factors associated with COVID-19 VHS scores in all survey respondents. The mean (SD) age of all survey respondents was 21.4 (6.3) years, and 61% (177/290) of respondents were female. Higher eHealth literacy (B=–0.26; P<.001) and perceived danger of COVID-19 (B=–0.17; P=.009) were associated with lower COVID-19 vaccine hesitancy, adjusting for age, sex, chronic disease status, previous flu vaccination, and perceived susceptibility to COVID-19. The main efficacy outcome of COVID-19 VHS score significantly decreased from 28.6 (preintervention) to 24.5 (postintervention), with a mean difference of –4.2 (P<.001) and an effect size (Cohen d) of 0.94. The intention to vaccinate increased from 3.0 to 3.9 (P<.001) in unvaccinated participants, whereas the intention to receive boosters increased from 1.9 to 2.8 (P<.001) in booster-hesitant participants. Willingness to encourage others to vaccinate increased from 2.7 to 3.0 (P=.04). At postintervention, the median (IQR) System Usability Scale score was 72.5 (65-77.5), whereas the median (IQR) recommendation score was 7 (6-8) on a scale from 0 to 10. In a post hoc 4-month follow-up, 82% (18/22) of initially unvaccinated participants reported having received the COVID-19 vaccine, whereas 29% (7/24) of booster-hesitant participants received boosters. This pilot study provided initial evidence to support the efficacy, usability, and acceptability of a chatbot for promoting COVID-19 vaccination in young adults who were unvaccinated or booster-hesitant.

As vaccine resources were distributed unevenly worldwide, sometimes there might have been shortages or delays in vaccine supply; therefore, considering the use of heterogeneous booster doses for Coronavirus disease 2019 (COVID-19) might be an alternative strategy. Therefore, we aimed to review the data available to evaluate and compare the effectiveness and safety of heterologous booster doses with homologous booster doses for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines. We searched relevant studies up to 27 April 2022. Random-effects inverse variance models were used to evaluate the vaccine effectiveness (VE) and its 95% confidence interval (CI) of COVID-19 outcomes and odds ratio (OR) and its CI of safety events. The Newcastle–Ottawa quality assessment scale and Cochrane Collaboration’s tool were used to assess the quality of the included cohort studies. A total of 23 studies involving 1,726,506 inoculation cases of homologous booster dose and 5,343,580 inoculation cases of heterologous booster dose was included. The VE of heterologous booster for the prevention of SARS-CoV-2 infection (VEheterologous = 96.10%, VEhomologous = 84.00%), symptomatic COVID-19 (VEheterologous = 56.80%, VEhomologous = 17.30%), and COVID-19-related hospital admissions (VEheterologous = 97.40%, VEhomologous = 93.20%) was higher than homologous booster. Compared with homologous booster group, there was a higher risk of fever (OR = 1.930, 95% CI, 1.199–3.107), myalgia (OR = 1.825, 95% CI, 1.079–3.089), and malaise or fatigue (OR = 1.745, 95% CI, 1.047–2.906) within 7 days after boosting, and a higher risk of malaise or fatigue (OR = 4.140, 95% CI, 1.729–9.916) within 28 days after boosting in heterologous booster group. Compared with homologous booster group, geometric mean neutralizing titers (GMTs) of neutralizing antibody for different SARS-CoV-2 variants and response rate of antibody and gama interferon were higher in heterologous booster group. Our findings suggested that both homologous and heterologous COVID-19 booster doses had great effectiveness, immunogenicity, and acceptable safety, and a heterologous booster dose was more effective, which would help make appropriate public health decisions and reduce public hesitancy in vaccination.

It is examined if any limitations in existing solid rocket propellant grain manufacturing methods adversely affected the payload capability of recent space launch vehicles. It is seen if the transition from heavy, segmented metal rocket motor casings to lightweight monolith composite casings is possible without loss of ability to design and realize high-performance grain configurations using simple and safe methods. Considering payload fraction as the comparative performance metric, recently flown solid rocket-propelled, small-lift launch vehicles were surveyed and ranked. Solid rocket boosters of underperforming launch vehicles were investigated for manufacturing factors influencing payload fraction by comparing them to boosters of better-performing launch vehicles in their weight class. Relationships between payload fraction and the solid boosters’ mass fractions, casing construction, shape of thrust profile, propellant grain configuration and method employed to manufacture the grain were analysed. It is shown that those launch vehicles that did not possess or use the technology necessary to manufacture high-performance grain configurations like undercut finocyl in monolith composite casings ended up having boosters delivering poor thrust profiles with high inert mass ultimately leading to low payload fractions.

A multistage rocket is considered, made according to the model: the central block (last stage), to which four side blocks (boosters) are connected in parallel. The paper assumes a linear dependence of the mass of the fuel tank block on the initial volume of the fuel in the tank, and the mass of each engine is assumed to be proportional to the initial mass of the rocket. It has been shown that the use of boosters with different fuel reserves, which are separated as they burn out, makes it possible to increase the delivered payload with minor design changes compared to the use of four identical boosters. The increase in the mass of the rocket payload has been estimated for several variants of using boosters with different fuel reserves.

A successful guaranteed launch of a mainline diesel locomotive is one of the most important and urgent problems of the rolling stock operation. Improvement of the start-up system of the main diesel locomotive when using a supercapacitor allows multiple restarts of diesel locomotives, meaning that the operation of the diesel locomotive can be stopped several times without wasting fuel in idle operations. In this study, we simulated the electric starting circuit of a diesel locomotive with a block of supercapacitors using the Matlab Simulink program. The simulation results show that using only a supercapacitor in the start-up system is impossible. Even though the supercapacitor produces the required current and voltage, its operating time is extremely insufficient. Using a storage battery along with a supercapacitor in the diesel locomotive start-up system is most effective. This reduces the peak current load on the standard battery. The article suggests an effective principle for starting a mainline diesel locomotive and provides an effective circuit solution involving a supercapacitor. Based on the booster stabilizer scheme, a new scheme was modeled to study the successful launch of a diesel locomotive that has various start-up systems. Applying a supercapacitor in the start-up system of a main diesel locomotive is proposed and the results of its use are presented. In addition, this study defines the basic requirements for using a system based on a battery in conjunction with a supercapacitor. Characteristics such as the temperature range of the system are shown.

•Children with rheumatic diseases are often treated with methotrexate and biologics.•Live-attenuated measles-mumps-rubella (MMR) or MMR varicella (MMRV) boosters did not cause severe adverse reactions.•Live-attenuated MMR or MMRV booster is safe in immunocompromised children with rheumatic disease.•Vaccination rates in pediatric patients with rheumatic diseases should increase. To collect retrospective data of patients with Juvenile Idiopathic Arthritis (JIA) and other rheumatic diseases who received live attenuated booster measles-mumps-rubella (MMR) or measles-mumps-rubella-varicella (MMR/V) during treatment with immunosuppressive therapy. Data from 13 pediatric rheumatology centers in 10 countries, including 234 patients, were collected. Mean age at diagnosis was 5 ± 2.7 years, 67% were girls. Among them, 211 (90.2%) had JIA and 110 (47%) were in remission on medication. Disease activity was low in 37%, high in 8%, and moderate in 8%. One hundred-twenty-four received MMR/V booster while on methotrexate (MTX); 3 reported local mild adverse events (AE). Among 62 on MTX + biologics and 9 patients who received a combination of 2 disease modifying antirheumatic drugs (DMARDs), 9 reported mild AE. Among 39 on biologics, 1 reported fever one day after booster vaccination. No vaccine-related infection of measles, rubella, mumps or varicella was reported, none of the patients developed disease flare, including those with high disease activity. In this retrospective study, live-attenuated MMR/V booster vaccines were safe for children with rheumatic diseases, on immunosuppressive therapies. This strengthens the Paediatric Rheumatology European Society (PReS) recommendation that vaccination with live attenuated vaccines in patients on immunosuppressive therapies can be considered individually, weighing the benefit of vaccination against the risk of inducing infection through vaccination. These data provide the basis for a prospective data collection study, planned by the PReS vaccination study group.