Determinants of information diffusion in online communication on vaccination: The benefits of visual displays

ObjectiveSocial media are an increasingly important source of information on the benefits and risks of vaccinations, but the high prevalence of misinformation provides challenges for informed vaccination decisions. It is therefore important to understand which messages are likely to diffuse online and why, and how relevant aspects—such as scientific facts on vaccination effectiveness—can be made more comprehensible and more likely to be shared. In two studies, we (i) explore which characteristics of messages on flu vaccination facilitate their diffusion in online communication, and (ii) whether visual displays (i.e., icon arrays) facilitate the comprehension and diffusion of scientific effectiveness information.MethodsIn Study 1, 208 participants each rated a random sample of 15 out of 63 messages on comprehensibility, trustworthiness, persuasiveness, familiarity, informativeness, valence, and arousal, and then reported which information they would share with subsequent study participants. In Study 2 (N = 758), we employed the same rating procedure for a selected set of 9 messages and experimentally manipulated how scientific effectiveness information was displayed.ResultsStudy 1 illustrated that scientific effectiveness information was difficult to understand and thus did not diffuse well. Study 2 demonstrated that visual displays improved the understanding of this information, which could, in turn, increase its social impact.ConclusionsThe comprehensibility of scientific information is an important prerequisite for its diffusion. Visual displays can facilitate informed vaccination decisions by rendering important information on vaccination effectiveness more transparent and increasing the willingness to share this information.     

Serological response with Heplisav-B® in prior Hepatitis B vaccine non-responders living with HIV

BackgroundAs people living with HIV (PLWH) are at risk for contracting Hepatitis B Virus (HBV), they should be screened for HBV and vaccinated if not immune. Seroconversion rates in PLWH receiving traditional recombinant HBV vaccines (Engerix-B® and Recombivax-HB®) have historically been low with at most 70% achieving immunity. In 2017, a recombinant, adjuvanted HBV vaccine (Heplisav-B®) was approved for use in HIV-negative patients.Heplisav-B® has shown superior seroprotection in this population compared to Engerix-B® and Recombivax-HB®, as well as interim analysis showing higher seropositivity rates in patients undergoing dialysis. However, its efficacy in PLWH is currently unknown. This study evaluates the rate of seroconversion following Heplisav-B® administration in PLWH with previous HBV vaccination failure.MethodsRetrospective, cross-sectional study at The Brooklyn Hospital Center’s HIV primary care clinic in Brooklyn, NY. HIV-positive adults who received at least two doses of Heplisav-B® and had previously failed to seroconvert after vaccination with Engerix-B® or Recombivax-HB® were included. The primary outcome is the percentage of PLWH who became seropositive following Heplisav-B®.ResultsA total of 67 patients met the inclusion criteria. Twenty-five (37.3%) PLWH had failed at least 2 courses of recombinant vaccines. Fifty-eight (86.6%) PLWH became seropositive (Anti-HBs > 10 mIU/mL) at least two months after completing Heplisav-B®. For the 9 (13.4%) patients that did not develop immunity, 3 (33%) had a detectable HIV RNA and 3 (33%) had a CD4 count < 200 cells/uL³.ConclusionsHeplisav-B® was highly effective in achieving immunity to HBV in PLWH who failed non-adjuvanted recombinant vaccines.     

COVID-19 vaccine – Long term immune decline and breakthrough infections

BackgroundSince the introduction of BNT162b2 mRNA COVID-19 vaccine by Pfizer in late 2020, efficacy and immunogenicity waning of COVID-19 vaccines was reported, and decision making regarding a booster remains a top priority worldwide, a decision that should be made based on breakthrough infection rate and antibody titer decline overtime.MethodsWe conducted a 5-month longitudinal prospective study involving vaccinated healthcare personnel, who were tested monthly for antibody titer, and sampled biweekly and on clinical indication for SARS-COV-2 polymerase chain reaction (PCR), to determine antibody decline and breakthrough infection.Results100 participants were recruited to the study. Antibody titer reached the climate after one month of the second dose of the vaccine, and declined rapidly thereafter: the median antibody levels were 895; 22,266; 9,682; 2,554 and 1,401 AU/ml in the day of the second dose, and in one month interval thereafter, respectively. In other words, four months after vaccination, the mean antibody level was 6% of the peak levels. During the study period, 4 breakthrough infections were diagnosed, 2 of which were asymptomatic, and the remaining two were mild cases; sharp elevation of antibody titer was seen after infection.ConclusionAntibody titer drops rapidly one month after the second dose of the vaccine. All infections within the study period were mild or asymptomatic, after which titer elevations were seen.     

Evaluation of a Campylobacter jejuni N-glycan-ExoA glycoconjugate vaccine to reduce C. jejuni colonisation in chickens

Campylobacter jejuni is the leading bacterial cause of human gastroenteritis worldwide and handling or consumption of contaminated poultry meat is the key source of infection. Glycoconjugate vaccines containing the C. jejuni N-glycan have been reported to be partially protective in chickens. However, our previous studies with subunit vaccines comprising the C. jejuni FlpA or SodB proteins with up to two or three C. jejuni N-glycans, respectively, failed to elicit significant protection. In this study, protein glycan coupling technology was used to add up to ten C. jejuni N-glycans onto a detoxified form of Pseudomonas aeruginosa exotoxin A (ExoA). The glycoprotein, G-ExoA, was evaluated for efficacy against intestinal colonisation of White Leghorn chickens by C. jejuni strains M1 and 11168H relative to unglycosylated ExoA. Chickens were challenged with the minimum dose required for reliable colonisation, which was 10² colony-forming units (CFU) for strain M1 and and 10⁴ CFU for strain 11168H. Vaccine-specific serum IgY was detected in chickens vaccinated with both ExoA and G-ExoA. However, no reduction in caecal colonisation by C. jejuni was observed. While the glycan dose achieved with G-ExoA was higher than FlpA- or SodB-based glycoconjugates that were previously evaluated, it was lower than that of glycoconjugates where protection against C. jejuni has been reported, indicating that protection may be highly sensitive to the amount of glycan presented and/or study-specific variables.     

Priming with social benefit information of vaccination to increase acceptance of COVID-19 vaccines

Vaccine hesitancy can be heightened due to increasing negative reports about vaccines. Emphasizing the social benefits of vaccination may shift individual attention from individual to social benefit of vaccination and hence promote prosocial vaccination. In six rounds of a population-based survey conducted over one major community epidemic of coronavirus disease 2019 (COVID-19) in Hong Kong from June to November 2020, we manipulated the question asking about acceptance of a COVID-19 vaccine with or without emphasizing the social benefit of vaccination against COVID-19 (prosocial priming) and monitored the changes of vaccine confidence by news media sentiment on vaccines. Population-weighted percentages of accepting COVID-19 vaccines by priming condition and vaccine confidence were compared across survey rounds. Logit regression models assessed the main effect of prosocial priming and the modification effects of vaccine confidence and perceived personal risk from COVID-19 on acceptance of COVID-19 vaccines. We found that prosocial priming significantly increased acceptance of COVID-19 vaccines across all survey rounds except for Round 3 when incidence of COVID-19 reached a peak. Vaccine confidence significantly declined in Round 6 when news media sentiment on vaccines became predominantly negative. The effect of prosocial priming on promoting vaccine acceptance was significantly greater in participants with low vaccine confidence and those perceiving the severity of COVID-19 to be mild/very mild. Our study suggests that packaging vaccination against COVID-19 as a prosocial behaviour can help overcome low vaccine confidence and promote prosocial vaccination particularly when disease incidence temporarily declines and the public perceive low severity of COVID-19.     

The cost-effectiveness of starting 23-valent pneumococcal polysaccharide vaccine and influenza vaccination at 50 vs. 65 years: A comparative modelling study

ObjectivesPneumococcal infection is a leading cause of morbidity and mortality. We aimed to evaluate the cost-effectiveness of 23-valent polysaccharide vaccine (PPV23) together with influenza vaccination or pneumococcal vaccination alone in adults starting from 50 years vs. 65 years in Hong Kong.MethodsA hypothetical population of 100,000 older adults was included in a Markov model with age ranging from 50 to 85 years to calculate the cost and quality-adjusted life-years (QALYs) gained for vaccination strategies, including: (1) annual influenza vaccine and PPV23 at 50 and 65 years; (2) annual influenza vaccine and PPV23 at 65 years (similar with the current vaccination programme); (3) PPV23 at 50 and 65 years; (4) PPV23 at 65 years; and (5) no vaccination. We evaluated the incremental cost-effectiveness ratio (ICER) and used Monte Carlo simulation for probabilistic sensitivity analysis. The cost-effectiveness threshold was extracted from previous literature.ResultsIn comparison with no vaccination, all strategies were cost-effective with ICERs less than the threshold (US$24,302 per QALY gained). When compared with no vaccination, strategies 1–4 saved US$ 49.5, US$ 94.9, US$ 584.3, and US$ 1114.2 to gain one QALY respectively. In comparison with strategy 2, strategy 1 spent US$ 195.3 to gain one QALY, whilst strategies 3 and 4 showed less effectiveness with increased costs.ConclusionsAll vaccination strategies were cost-effective, among which the strategy of PPV23 at 50/65 years with annual influenza vaccine was cost-effective even in comparison with current vaccination programme. These findings could help inform the design and implementation of vaccination strategies.     

Aggregating human judgment probabilistic predictions of the safety,efficacy, and timing of a COVID-19 vaccine

Safe, efficacious vaccines were developed to reduce the transmission of SARS-CoV-2 during the COVID-19 pandemic. But in the middle of 2020, vaccine effectiveness, safety, and the timeline for when a vaccine would be approved and distributed to the public was uncertain. To support public health decision making, we solicited trained forecasters and experts in vaccinology and infectious disease to provide monthly probabilistic predictions from July to September of 2020 of the efficacy, safety, timing, and delivery of a COVID-19 vaccine. We found, that despite sparse historical data, a linear pool—a combination of human judgment probabilistic predictions—can quantify the uncertainty in clinical significance and timing of a potential vaccine. The linear pool underestimated how fast a therapy would show a survival benefit and the high efficacy of approved COVID-19 vaccines. However, the linear pool did make an accurate prediction for when a vaccine would be approved by the FDA. Compared to individual forecasters, the linear pool was consistently above the median of the most accurate forecasts. A linear pool is a fast and versatile method to build probabilistic predictions of a developing vaccine that is robust to poor individual predictions. Though experts and trained forecasters did underestimate the speed of development and the high efficacy of a SARS-CoV-2 vaccine, linear pool predictions can improve situational awareness for public health officials and for the public make clearer the risks, rewards, and timing of a vaccine.     

Looking ahead: Caregivers’ COVID-19 vaccination intention for children 5 years old and younger using the health belief model

COVID-19 vaccine hesitancy is a significant public health issue. While vaccines are not yet available for children, clinical trials are underway, and children will likely be an important factor in the U.S. reaching herd immunity. However, little research has been conducted to examine parents’ intention to vaccinate their young children for COVID-19.MethodAn online survey with a national U.S. sample of 682 primary caregivers of children under age six assessed variables associated with intention to accept the COVID-19 vaccine for their children from November 13, 2020, to December 8, 2020.ResultsCaregivers whose child received a recent influenza vaccine, as well as those with previous experience COVID-19, were more likely to express COVID-19 vaccination intention for their young child. Identifying as female was associated with lower COVID-19 vaccination intention, while identifying as Hispanic or Latino was associated with higher intention. Health Belief Model variables of perceived severity of COVID-19 for their child, as well as vaccine confidence, were positive predictors of COVID-19 vaccine intention and mediated the relationship between prior behavior, demographic variables, and intention.ConclusionsThe findings highlight the importance of early, proactive COVID-19 vaccination education efforts directed at caregivers, including those with young children. Vaccines for young children will likely become a necessary part of ending the pandemic’s impact in school settings. Operationally, COVID-19 vaccination may also become a part of childhood vaccination schedules. Understanding the beliefs and intentions of caregivers of young children before vaccinations are recommended for children will enable public health officials and medical practitioners to prepare in advance.     

Effective improvements to the live-attenuated Newcastle disease virus vaccine by polyethylenimine-based biomimetic silicification

Live and killed vaccines impart a significant role in preventing of Newcastle disease (ND) in China. Vaccine efficacy could be ameliorated by improving vaccine-induced cellular immunity and antibody persistency. Previous studies substantiated the potency of silicon dioxide (SiO₂) in the control-release of drugs and as a vaccine adjuvant, and polyethylenimine (PEI) merits as a mucosal adjuvanticity with electro-positivity. The present study employed SiO₂ and PEI to prepare biomimetic silicon mineralized nanoparticle G7M@SiO₂-PEI and microparticle (SiO₂ + PEI)@G7M vaccines of G7M, a candidate for live attenuated vaccine of genotype VII Newcastle disease virus (NDV). The zeta potential experiment confirmed the significant increase in the average zeta potential of the nanoparticle G7M@SiO₂-PEI and microparticle (SiO₂ + PEI)@G7M relative to G7M before mineralization. The results of RT-qPCR revealed more than 99% mineralization efficiency of the G7M@SiO₂-PEI and (SiO₂ + PEI)@G7M. The morphology detected by transmission electron microscopy reported that the diameters of G7M@SiO₂-PEI were similar to those of G7M, while for (SiO₂ + PEI)@G7M, it was about five times larger than that of G7M. Silicon was detected on the surface of both mineralization particles, except for G7M, as observed from the elemental distribution detected by elemental mapping and energy dispersive X-ray spectrogram. Indirect immunofluorescence assays validated that mineralization virus have replicated ability in BHK-21F cells. In vivo experiments revealed higher than 5.50 log₂ of antibody in nanoparticles G7M@SiO₂-PEI group until 10-week post-vaccination, and significant proliferation of antigen-specific CD3⁺CD4⁺ in nanoparticles G7M@SiO₂-PEI immunized group corroborated improved cellular immune responses. Vaccines provided full protection to the immunized chickens, whereas all the chickens receiving mock immunizations succumbed to the disease. Overall, our study concluded the efficacy of biomimetic mineralization of live attenuated vaccine in nanoparticles to improve humoral and cellular immune responses.     

Safety of measles and pertussis-containing vaccines in children with autism spectrum disorders

ObjectivesTo determine whether children aged 4–7 years with a diagnosis of autism spectrum disorders (ASD) were at increased risk of fever, febrile seizures, or emergency department (ED) visits following measles- or pertussis-containing vaccines compared with children without ASD.MethodsThe study included children born between 1995–2012, aged 4–7 years at vaccination, and members of six healthcare delivery systems within Vaccine Safety Datalink. We conducted self-controlled risk interval analyses comparing rates of outcomes in risk and control intervals within each group defined by ASD status, and then compared outcome rates between children with and without ASD, in risk and control intervals, by estimating difference-in-differences using logistic regressions.ResultsThe study included 14,947 children with ASD and 1,650,041 children without ASD. After measles- or pertussis-containing vaccination, there were no differences in association between children with and without ASD for fever (ratio of rate ratio for measles-containing vaccine = 1.07, 95% CI 0.58–1.96; for pertussis-containing vaccine = 1.16, 95% CI 0.63–2.15) or ED visits (ratio of rate ratio for measles-containing vaccine = 1.11, 95% CI 0.80–1.54; for pertussis-containing vaccine = 0.87, 95% CI 0.59–1.28). Febrile seizures were rare. Pertussis-containing vaccines were associated with small increased risk of febrile seizures in children without ASD.ConclusionChildren with ASD were not at increased risk for fever or ED visits compared with children without ASD following measles- or pertussis-containing vaccines. These results may provide further reassurance that these vaccines are safe for all children, including those with ASD.