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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.

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.

•rVEs show increased protection in eligible people receiving (vs not) a booster dose.•Overall rVE of any 2nd booster against COVID-19 hospitalization was 24.7 %.•rVEs were similar with 2nd booster doses of AZD1222 (29.4 %) and BNT162b2 (25.5 %).•rVE of any 1st booster vs having only received a primary series was 46.8 %.•The rVEs of 1st boosters of AZD1222 (42.5 %) and BNT162b2 (50.8 %) were similar. Although COVID-19 booster vaccination is widely recommended, there is limited long-term, population-level, real-world evidence on the magnitude of improved protection against severe COVID-19 conferred by boosting with monovalent COVID-19 vaccines developed against ancestral SARS-CoV-2, especially in low- or middle-income countries. We present interim results from the first large-scale assessment of the relative vaccine effectiveness (rVE) of first and second booster doses against severe COVID-19 in a low-/middle-income country. REFORCO-Brazil is an ongoing, test-negative case-control study (NCT05697705) utilizing Brazil national severe acute respiratory syndrome (SARS) surveillance and vaccination data. In SARS hospitalizations from August 1, 2021 to July 31, 2022, we matched test-positive (via SARS-CoV-2 antigen/reverse transcription polymerase chain reaction [RT-PCR]) cases and test-negative case-controls (via RT-PCR) based on admission date, preceding vaccinations, and age. We evaluated the rVEs of four monovalent COVID-19 vaccines (AZD1222, Ad26.COV2.S, CoronaVac, and BNT162b2) as second boosters compared with any first boosters received ≥4 months previously, and as first boosters compared with primary-series vaccinations completed ≥4 months previously. The overall rVE of second boosters, from 5668 (2238 test-positive) evaluated hospitalizations, was 24.7 % (95 % confidence interval [CI]: 12.6–35.1); the overall rVE of first boosters, from 30,272 (12,063 test-positive) hospitalizations, was 46.8 % (95 % CI: 43.3–50.0). The rVEs of AZD1222 and BNT162b2 were similar: 29.4 % (95 % CI: 8.6–45.5) and 25.5 % (95 % CI: 4.2–42.2), respectively, for second boosters; and 42.5 % (95 % CI: 28.0–54.0) and 50.8 % (95 % CI: 47.5–54.0), respectively, for first boosters. In general, rVEs were higher in elderly (≥80 years) and immunocompromised/high-risk individuals. Our results support the use of AZD1222 and other adenoviral/mRNA vaccine boosters to maintain protection against COVID-19 hospitalization from Omicron subvariants, including in elderly and immunocompromised individuals at increased risk of accelerated waning or severe outcomes.

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.

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.

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.

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.

•School-age and adolescent boosters protect targeted age groups against pertussis.•Pertussis incidence among infants remained unchanged since introduction of boosters.•Boosters may have offered indirect protection among adults.•Recent increases in incidence among children warrant evaluation of vaccination schedule. The acellular pertussis vaccine has been used in the Norwegian national immunisation program since 1998. Following an increase in pertussis incidence in all age groups, booster doses were introduced for 7–8-year-olds in 2006, and for 15–16-year-olds in 2013. We assessed the effects of the booster doses on pertussis incidence in different age groups to inform potential changes in vaccination policy. We included all pertussis cases notified to the Norwegian Surveillance System for Communicable Diseases in 1998–2019. We calculated annual incidence rates (IR, per 100,000 inhabitants) by age group. We estimated average annual changes in IRs (incidence rate ratios, IRR) for each age group for 2006–2012 and 2013–2019 using Poisson regression. In 1998–2019, 74,675 cases of pertussis were notified. Coinciding with booster introduction, between 2006 and 2012 the IR decreased among 8–15-year-olds (from 433 to 199/100,000, IRR 0.89 [95% confidence interval 0.88–0.90]). A similar decrease was seen between 2013 and 2019 among 16–19-year-olds (from 171 to 77/100,000, IRR 0.84 [0.82–0.86]). There was no significant change in IRs among children < 1 year of age between 2006 and 2012 (IRR 0.99 [0.95–1.04]) or 2013–2019 (IRR 0.96 [0.91–1.02]). The IR decreased in both periods among adults aged 20–39 and 40+ (IRR 0.94 [0.93–0.95] and 0.92 [0.91–0.92] in 2006–2012; IRR 0.97 [0.96–0.99] and 0.97 [0.96–0.99] in 2013–2019, respectively). Despite steady, high vaccination coverage, in 2013–2019, there was an increase in the IR among children aged 1–7 (63 to 86/100,000, IRR 1.05 [1.03–1.07]) and 8–15 years (88 to 122/100,000, IRR 1.08 [1.06–1.10]). Pertussis booster doses have offered direct protection in the targeted age groups. Our findings suggest indirect protection in adults, while the incidence in infants hasn’t changed. The recent increase in IRs among 1–15-year-olds warrants close monitoring and further evaluation of the vaccination schedule.

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.