A game dynamic model for delayer strategies in vaccinating behaviour for pediatric infectious diseases

Several studies have found that some parents delay the age at which their children receive pediatric vaccines due to perception of higher vaccine risk at the recommended age of vaccination. This has been particularly apparently during the Measles-Mumps-Rubella scare in the United Kingdom. Under a voluntary vaccination policy, vaccine coverage in certain age groups is a potentially complex interplay between vaccinating behaviour, disease dynamics, and age-specific risk factors. Here, we construct an age-structured game dynamic model, where individuals decide whether to vaccinate according to imitation dynamics depending on age-dependent disease prevalence and perceived risk of vaccination. Individuals may be timely vaccinators, delayers, or non-vaccinators. The model exhibits multiple equilibria and a broad range of possible dynamics. For certain parameter regimes, the proportion of timely vaccinators and delayers oscillate in an anti-phase fashion in response to oscillations in infection prevalence. Under an exogenous change to the perceived risk of vaccination as might occur during a vaccine scare, the model can also capture an increase in delayer strategists similar in magnitude to that observed during the Measles-Mumps-Rubella vaccine scare in the United Kingdom. Our model also shows that number of delayers steadily increases with increasing severity of the scare, whereas it saturates to specific value with increases in duration of the scare. Finally, by comparing the model dynamics with and without the option of a delayer strategy, we show that adding a third delayer strategy can have a stabilizing effect on model dynamics. In an era where individual choice—rather than accessibility—is becoming an increasingly important determinant of vaccine uptake, more infectious disease models may need to use game theory or related techniques to determine vaccine uptake.     

The Effect of Perceived Risks on the Demand for Vaccination: Results from a Discrete Choice Experiment

The demand for vaccination against infectious diseases involves a choice between vaccinating and not vaccinating, in which there is a trade-off between the benefits and costs of each option. The aim of this paper is to investigate these trade-offs and to estimate how the perceived prevalence and severity of both the disease against which the vaccine is given and any vaccine associated adverse events (VAAE) might affect demand. A Discrete Choice Experiment (DCE) was used to elicit stated preferences from a representative sample of 369 UK mothers of children below 5 years of age, for three hypothetical vaccines. Cost was included as an attribute, which enabled estimation of the willingness to pay for different vaccines having differing levels of the probability of occurrence and severity of both the infection and VAAE. The results suggest that the severity of the health effects associated with both the diseases and VAAEs exert an important influence on the demand for vaccination, whereas the probability of these events occurring was not a significant predictor. This has important implications for public health policy, which has tended to focus on the probability of these health effects as the main influence on decision making. Our results also suggest that anticipated regrets about the consequences of making the wrong decision also exert an influence on demand.     

Ethnic inequalities in COVID-19 vaccine uptake and comparison to seasonal influenza vaccine uptake in Greater Manchester,UK: A cohort study

BackgroundCOVID-19 vaccine uptake is lower amongst most minority ethnic groups compared to the White British group in England, despite higher COVID-19 mortality rates. Here, we add to existing evidence by estimating inequalities for 16 minority ethnic groups, examining ethnic inequalities within population subgroups, and comparing the magnitudes of ethnic inequalities in COVID-19 vaccine uptake to those for routine seasonal influenza vaccine uptake.Methods and findingsWe conducted a retrospective cohort study using the Greater Manchester Care Record, which contains de-identified electronic health record data for the population of Greater Manchester, England. We used Cox proportional hazards models to estimate ethnic inequalities in time to COVID-19 vaccination amongst people eligible for vaccination on health or age (50+ years) criteria between 1 December 2020 and 18 April 2021 (138 days of follow-up). We included vaccination with any approved COVID-19 vaccine, and analysed first-dose vaccination only. We compared inequalities between COVID-19 and influenza vaccine uptake adjusting by age group and clinical risk, and used subgroup analysis to identify populations where inequalities were widest. The majority of individuals (871,231; 79.24%) were White British. The largest minority ethnic groups were Pakistani (50,268; 4.75%), ‘other White background’ (43,195; 3.93%), ‘other ethnic group’ (34,568; 3.14%), and Black African (18,802; 1.71%). In total, 83.64% (919,636/1,099,503) of eligible individuals received a COVID-19 vaccine. Uptake was lower compared to the White British group for 15 of 16 minority ethnic groups, with particularly wide inequalities amongst the groups ‘other Black background’ (hazard ratio [HR] 0.42, 95% CI 0.40 to 0.44), Black African (HR 0.43, 95% CI 0.42 to 0.44), Arab (HR 0.43, 95% CI 0.40 to 0.48), and Black Caribbean (HR 0.43, 95% CI 0.42 to 0.45). In total, 55.71% (419,314/752,715) of eligible individuals took up influenza vaccination. Compared to the White British group, inequalities in influenza vaccine uptake were widest amongst the groups ‘White and Black Caribbean’ (HR 0.63, 95% CI 0.58 to 0.68) and ‘White and Black African’ (HR 0.67, 95% CI 0.63 to 0.72). In contrast, uptake was slightly higher than the White British group amongst the groups ‘other ethnic group’ (HR 1.11, 95% CI 1.09 to 1.12) and Bangladeshi (HR 1.08, 95% CI 1.05 to 1.11). Overall, ethnic inequalities in vaccine uptake were wider for COVID-19 than influenza vaccination for 15 of 16 minority ethnic groups. COVID-19 vaccine uptake inequalities also existed amongst individuals who previously took up influenza vaccination. Ethnic inequalities in COVID-19 vaccine uptake were concentrated amongst older and extremely clinically vulnerable adults, and the most income-deprived. A limitation of this study is the focus on uptake of the first dose of COVID-19 vaccination, rather than full COVID-19 vaccination.ConclusionsEthnic inequalities in COVID-19 vaccine uptake exceeded those for influenza vaccine uptake, existed amongst those recently vaccinated against influenza, and were widest amongst those with greatest COVID-19 risk. This suggests the COVID-19 vaccination programme has created additional and different inequalities beyond pre-existing health inequalities. We suggest that further research and policy action is needed to understand and remove barriers to vaccine uptake, and to build trust and confidence amongst minority ethnic communities.

Ruth Elizabeth Watkinson and colleagues estimate inequalities in Covid-19 vaccine uptake for 16 minority ethnic groups and compare them to those in routine seasonal Influenza vaccine uptake.     

Influenza and Pneumococcal Vaccination Uptake in Patients with Rheumatoid Arthritis Treated with Immunosuppressive Therapy in the UK: A Retrospective Cohort Study Using Data from the Clinical Practice Research Datalink

IntroductionGuidelines for the management of rheumatoid arthritis (RA) recommend using influenza and pneumococcal vaccinations to mitigate infection risk. The level of adherence to these guidelines is not well known in the UK. The aims of this study were to describe the uptake of influenza and pneumococcal vaccinations in patients with RA in the UK, to compare the characteristics of those vaccinated to those not vaccinated and to compare vaccination rates across regions of the UK.MethodsA retrospective cohort study of adults diagnosed with incident RA and treated with non-biologic immunosuppressive therapy, using data from a large primary care database. For the influenza vaccination, patients were considered unvaccinated on 1st September each year and upon vaccination their status changed to vaccinated. For pneumococcal vaccination, patients were considered vaccinated after their first vaccination until the end of follow-up. Patients were stratified by age 65 at the start of follow-up, given differences in vaccination guidelines for the general population.ResultsOverall (N = 15,724), 80% patients received at least one influenza vaccination, and 50% patients received a pneumococcal vaccination, during follow-up (mean 5.3 years). Of those aged below 65 years (N = 9,969), 73% patients had received at least one influenza vaccination, and 43% patients received at least one pneumococcal vaccination. Of those aged over 65 years (N = 5,755), 91% patients received at least one influenza vaccination, and 61% patients had received at least one pneumococcal vaccination. Those vaccinated were older, had more comorbidity and visited the GP more often. Regional differences in vaccination rates were seen with the highest rates in Northern Ireland, and the lowest rates in London.ConclusionsOne in five patients received no influenza vaccinations and one in two patients received no pneumonia vaccine over five years of follow-up. There remains significant scope to improve uptake of vaccinations in patients with RA.     

Adjuvanted vaccines against influenza in the elderly

Influenza is an important public health issue,especially with the aging of the population,since the most serious consequences of the illness affect the elderly.Between 1979 and 2001,approximately 41000...     

Focus: Health Equity: COVID-19 Healthcare Inequity: Lessons Learned from Annual Influenza Vaccination Rates to Mitigate COVID-19 Vaccine Disparities

The COVID-19 pandemic has infected 33 million Americans and resulted in more than 600,000 deaths as of late Spring 2021. Black, Indigenous, and Latinx (BIL) people are disproportionately infected, hospitalized, and dying. Effective vaccines were rapidly developed and have been widely available in the United States since their initial rollout in late 2020-early 2021 but vaccination rates in BIL communities have remained low compared with non-BIL communities. Limited access to the vaccine, lack of customized information, and mistrust of the medical system, all contribute to vaccine hesitancy and low vaccination rates. Regrettably, COVID-19 is not the only vaccine-preventable illness with racial/ethnic inequities. Similar inequities are seen with the seasonal influenza vaccine. We review the racial/ethnic health disparities in COVID-19 illness and vaccination rates and what inequities contribute to these disparities. We use evidence from the seasonal influenza vaccination efforts to inform potential strategies to attenuate these inequities. The development of effective and sustainable strategies to improve vaccination rates and reduce factors that result in health inequities is essential in managing current and future pandemics and promoting improved health for all communities.     

Focus: Vaccines: COVID-19 Vaccine Hesitancy in Israel Immediately Before the Vaccine Operation

The development of a vaccine for COVID-19 presented hope for a way out of the global crisis caused by the virus. However, a potential barrier may be vaccine hesitancy, and identifying the factors that affect it is critical, especially concerning a new vaccine technology. The purpose of this research is to identify the factors that effects vaccine hesitancy by using a holistic view. The data were collected from 504 people in December 2020, 3 days before the vaccine operation started in Israel. The analysis included three categories of determinants: (1) contextual influences; (2) health records; and (3) perceived health attitudes. The results indicate that different sets of variables affect willingness to accept the vaccine among the whole spectrum of the vaccine-hesitant and the undecided subsample. In the full sample, gender, age, income, influenza vaccine, perceived trust, perceived susceptibility, perceived benefits, and perceived barriers affected vaccine acceptance. The perceived level of suffering from COVID-19 was associated with willingness to vaccinate, and when religious beliefs increased, the intention to vaccinate decreased. For the undecided subsample, the factors included gender, influenza vaccine, trust in the vaccine company, and perceived vaccine benefits and barriers. The results suggest that efforts of governments and health institutions should focus on women and highlight the vaccine as an opportunity to “go back to normal” without worries. Those results will help implement vaccine strategy in the following cases: if infant vaccination is pursued and if emergency vaccines or new vaccine technologies emerge for another pandemic as well.     

Socioeconomic Status and Other Related Factors of Seasonal Influenza Vaccination in the South Korean Adult Population Based on a Nationwide Cross-Sectional Study

PurposeWe investigated the association between seasonal influenza vaccination in South Korea and socioeconomic status (SES) as well as other potential related factors.MethodsThe study was based on data obtained in the Korea National Health and Nutrition Examination Survey from 2010 to 2011. Education level and household income were used as indicators for SES. Univariate and multiple logistic regression analyses were used to evaluate SES and other demographic variables as related factors for influenza vaccination, the primary outcome.ResultsHigher household income was positively associated with higher vaccine uptake in the younger (19–49 years) group [adjusted odds ratio (aOR) 1.55, 95% confidence interval (CI) 1.08–2.23], whereas the low-income and low-education group had increased vaccination coverage than the middle-income and middle-education group in the older (≥ 50 years) group (aOR 1.36, 95% CI 1.09–1.69). Current smokers tend to be unvaccinated in all age groups. Among individuals aged ≥ 50, older age, mild to moderate alcohol consumption, regular exercise, and having co-morbidities were positively associated with vaccination, while those who self-reported their health status as good were less likely to be vaccinated.ConclusionsThe relationship between SES and seasonal influenza vaccination coverage differed between the age groups throughout the adult South Korean population. Public health policies need to address these inequalities.     

Understanding COVID-19 vaccine demand and hesitancy: A nationwide online survey in China

BackgroundThis study attempts to understand coronavirus disease 2019 (COVID-19) vaccine demand and hesitancy by assessing the public’s vaccination intention and willingness-to-pay (WTP). Confidence in COVID-19 vaccines produced in China and preference for domestically-made or foreign-made vaccines was also investigated.MethodsA nationwide cross-sectional, self-administered online survey was conducted on 1–19 May 2020. The health belief model (HBM) was used as a theoretical framework for understanding COVID-19 vaccination intent and WTP.ResultsA total of 3,541 complete responses were received. The majority reported a probably yes intent (54.6%), followed by a definite yes intent (28.7%). The perception that vaccination decreases the chances of getting COVID-19 under the perceived benefit construct (OR = 3.14, 95% CI 2.05–4.83) and not being concerned about the efficacy of new COVID-19 vaccines under the perceived barriers construct (OR = 1.65, 95% CI 1.31–2.09) were found to have the highest significant odds of a definite intention to take the COVID-19 vaccine. The median (interquartile range [IQR]) of WTP for COVID-19 vaccine was CNY¥200/US$28 (IQR CNY¥100–500/USD$14–72). The highest marginal WTP for the vaccine was influenced by socio-economic factors. The majority were confident (48.7%) and completely confident (46.1%) in domestically-made COVID-19 vaccine. 64.2% reported a preference for a domestically-made over foreign-made COVID-19 vaccine.ConclusionsThe findings demonstrate the utility of HBM constructs in understanding COVID-19 vaccination intent and WTP. It is important to improve health promotion and reduce the barriers to COVID-19 vaccination.     

Improving community coverage of oral cholera mass vaccination campaigns: lessons learned in zanzibar

Background

Recent research in two cholera-endemic communities of Zanzibar has shown that a majority (∼94%) of the adult population was willing to receive free oral cholera vaccines (OCVs). Since OCV uptake in the 2009 campaign reached only ∼50% in these communities, an evaluation of social and cultural factors and of barriers was conducted to understand this difference for future cholera control planning.

Methodology/Principal Findings

A random sample of 367 adult peri-urban and rural community residents (46.6% immunized vs. 53.4% unimmunized) was studied with a semi-structured interview that inquired about social and cultural features of cholera depicted in a vignette and barriers to OCV uptake. Symptoms (rectal pain, loose skin only in rural community) and perceived causes (uncovered food, contact with contaminated water) specific for severe diarrhea were associated with uptake. Purchasing drugs from pharmacies to stop diarrhea and vomiting was negatively associated with uptake. Increasing household size, age and previous enteric illness episode were positively related to uptake, the latter only at the rural site. The most prominent barrier to uptake was competing obligations or priorities (reported by 74.5%, identified as most important barrier by 49.5%). Next most prominent barriers were lacking information about the campaign (29.6%, 12.2%), sickness (14.3%, 13.3%) and fear of possible vaccine side effects (15.3%, 5.6%). The majority of unvaccinated respondents requested repetition of the vaccination with free OCVs.

Conclusions/Significance

Factors associated with uptake indicated a positive impact of the vaccination campaign and of sensitization activities on vaccine acceptance behavior. Unlike communities opposed to cholera control or settings where public confidence in vaccines is lacking, identified barriers to uptake indicated a good campaign implementation and trust in the health system. Despite prospects and demand for repeating the vaccination, local decision-makers should reconsider how careful logistical arrangements may improve community coverage and thus effectiveness of vaccination campaigns.     

Serologic Vaccination Response after Solid Organ Transplantation: A Systematic Review

Background

Infectious diseases after solid organ transplantation (SOT) are one of the major complications in transplantation medicine. Vaccination-based prevention is desirable, but data on the response to active vaccination after SOT are conflicting.

Methods

In this systematic review, we identify the serologic response rate of SOT recipients to post-transplantation vaccination against tetanus, diphtheria, polio, hepatitis A and B, influenza, Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitides, tick-borne encephalitis, rabies, varicella, mumps, measles, and rubella.

Results

Of the 2478 papers initially identified, 72 were included in the final review. The most important findings are that (1) most clinical trials conducted and published over more than 30 years have all been small and highly heterogeneous regarding trial design, patient cohorts selected, patient inclusion criteria, dosing and vaccination schemes, follow up periods and outcomes assessed, (2) the individual vaccines investigated have been studied predominately only in one group of SOT recipients, i.e. tetanus, diphtheria and polio in RTX recipients, hepatitis A exclusively in adult LTX recipients and mumps, measles and rubella in paediatric LTX recipients, (3) SOT recipients mount an immune response which is for most vaccines lower than in healthy controls. The degree to which this response is impaired varies with the type of vaccine, age and organ transplanted and (4) for some vaccines antibodies decline rapidly.

Conclusion

Vaccine-based prevention of infectious diseases is far from satisfactory in SOT recipients. Despite the large number of vaccination studies preformed over the past decades, knowledge on vaccination response is still limited. Even though the protection, which can be achieved in SOT recipients through vaccination, appears encouraging on the basis of available data, current vaccination guidelines and recommendations for post-SOT recipients remain poorly supported by evidence. There is an urgent need to conduct appropriately powered vaccination trials in well-defined SOT recipient cohorts.     

Disease Interventions Can Interfere with One Another through Disease-Behaviour Interactions

Theoretical models of disease dynamics on networks can aid our understanding of how infectious diseases spread through a population. Models that incorporate decision-making mechanisms can furthermore capture how behaviour-driven aspects of transmission such as vaccination choices and the use of non-pharmaceutical interventions (NPIs) interact with disease dynamics. However, these two interventions are usually modelled separately. Here, we construct a simulation model of influenza transmission through a contact network, where individuals can choose whether to become vaccinated and/or practice NPIs. These decisions are based on previous experience with the disease, the current state of infection amongst one''s contacts, and the personal and social impacts of the choices they make. We find that the interventions interfere with one another: because of negative feedback between intervention uptake and infection prevalence, it is difficult to simultaneously increase uptake of all interventions by changing utilities or perceived risks. However, on account of vaccine efficacy being higher than NPI efficacy, measures to expand NPI practice have only a small net impact on influenza incidence due to strongly mitigating feedback from vaccinating behaviour, whereas expanding vaccine uptake causes a significant net reduction in influenza incidence, despite the reduction of NPI practice in response. As a result, measures that support expansion of only vaccination (such as reducing vaccine cost), or measures that simultaneously support vaccination and NPIs (such as emphasizing harms of influenza infection, or satisfaction from preventing infection in others through both interventions) can significantly reduce influenza incidence, whereas measures that only support expansion of NPI practice (such as making hand sanitizers more available) have little net impact on influenza incidence. (However, measures that improve NPI efficacy may fare better.) We conclude that the impact of interference on programs relying on multiple interventions should be more carefully studied, for both influenza and other infectious diseases.     

Protection against Tetanus by Needle-Free Inoculation of Adenovirus-Vectored Nasal and Epicutaneous Vaccines

The effectiveness of vaccination programs would be enhanced greatly through the availability of vaccines that can be administered simply and, preferably, painlessly without the need for timed booster injections. Tetanus is a prime example of a disease that is readily preventable by vaccination but remains a major threat to public health due to the problems associated with administration of the present vaccine. Here we show that a protective immune response against live Clostridium tetani infection in mice can be elicited by an adenovirus vector encoding the tetanus toxin C fragment when administered as a nasal or epicutaneous vaccine. The results suggest that these vaccination modalities would be effective needle-free alternatives. This is the first demonstration that absorption of a small number of vectored vaccines into the skin following topical application of a patch can provide protection against live bacteria in a disease setting.     

Monitoring vaccine safety during an influenza pandemic

In the event that a vaccine is available during an influenza pandemic, vaccine safety monitoring will occur as part of comprehensive public health surveillance of the vaccination campaign. Though inactivated influenza vaccines have been widely used in the United States and much is known about their safety profile, attention will need to be paid to both common self-limited adverse reactions and rarer, more serious events that may or may not be causally related to vaccination. The primary surveillance systems used to generate and test hypotheses about vaccine safety concerns are the Vaccine Adverse Event Reporting System (VAERS) and the Vaccine Safety Datalink (VSD), respectively. Examples of recent use of these systems to investigate influenza vaccine safety and enhancements planned for use during a pandemic are presented. Ethical issues that will need to be addressed as part of an overall vaccine safety response include risk communication and injury compensation. Advance planning and the use of available technologic solutions are needed to respond to the scientific and logistic challenges involved in safely implementing mass vaccination during a pandemic.     

Healthy Bodies,Toxic Medicines: College Students and the Rhetorics of Flu Vaccination

This article examines flu vaccination beliefs and practices produced during a survey of undergraduate students in Spring 2012 (IRB#10-732). This research uses the methods of rhetorical analysis — or the study of persuasive features and arguments used in language — to examine statements respondents made regarding flu and flu vaccine. In these responses, students generated unique categories of arguments about the perceived dangers of flu vaccination, including the assertion that vaccines cause disease (including illnesses and conditions other than flu), that vaccines are toxic medicines, and that vaccines carry unknown, population-wide risks that are inadequately acknowledged. This study provides insight into vaccination beliefs and rationales among a population at risk of flu (college students) and suggests that further study of this population may yield important keys to addressing flu vaccine concerns as expressed by college students. Rhetorical analysis also offers a useful set of methods to understanding vaccination beliefs and practices, adding to existing methods of study and analysis of vaccination practices and beliefs in medicine and public health.     

Attitudes toward and uptake of H1N1 vaccine among health care workers during the 2009 H1N1 pandemic

Background

Though recommended by many and mandated by some, influenza vaccination rates among health care workers, even in pandemics, remain below optimal levels. The objective of this study was to assess vaccination uptake, attitudes, and distinguishing characteristics (including doctor-nurse differences) of health care workers who did and did not receive the pandemic H1N1 influenza vaccine in late 2009.

Methodology/Principal Findings

In early 2010 we mailed a self-administered survey to 800 physicians and 800 nurses currently licensed and practicing in Minnesota. 1,073 individuals responded (cooperation rate: 69%). 85% and 62% of Minnesota physicians and nurses, respectively, reported being vaccinated. Accurately estimating the risk of vaccine side effects (OR 2.0; 95% CI 1.5–2.7), agreeing with a professional obligation to be vaccinated (OR 10.1; 95% CI 7.1–14.2), an ethical obligation to follow public health authorities'' recommendations (OR 9.9; 95% CI 6.6–14.9), and laws mandating pandemic vaccination (OR 3.1; 95% CI 2.3–4.1) were all independently associated with receiving the H1N1 influenza vaccine.

Conclusions/Significance

While a majority of health care workers in one midwestern state reported receiving the pandemic H1N1 vaccine, physicians and nurses differed significantly in vaccination uptake. Several key attitudes and perceptions may influence health care workers'' decisions regarding vaccination. These data inform how states might optimally enlist health care workers'' support in achieving vaccination goals during a pandemic.     

Effectiveness of Inactivated Influenza Vaccines in Preventing Influenza-Associated Deaths and Hospitalizations among Ontario Residents Aged ≥65 Years: Estimates with Generalized Linear Models Accounting for Healthy Vaccinee Effects

Background

Estimates of the effectiveness of influenza vaccines in older adults may be biased because of difficulties identifying and adjusting for confounders of the vaccine-outcome association. We estimated vaccine effectiveness for prevention of serious influenza complications among older persons by using methods to account for underlying differences in risk for these complications.

Methods

We conducted a retrospective cohort study among Ontario residents aged ≥65 years from September 1993 through September 2008. We linked weekly vaccination, hospitalization, and death records for 1.4 million community-dwelling persons aged ≥65 years. Vaccine effectiveness was estimated by comparing ratios of outcome rates during weeks of high versus low influenza activity (defined by viral surveillance data) among vaccinated and unvaccinated subjects by using log-linear regression models that accounted for temperature and time trends with natural spline functions. Effectiveness was estimated for three influenza-associated outcomes: all-cause deaths, deaths occurring within 30 days of pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations.

Results

During weeks when 5% of respiratory specimens tested positive for influenza A, vaccine effectiveness among persons aged ≥65 years was 22% (95% confidence interval [CI], −6%–42%) for all influenza-associated deaths, 25% (95% CI, 13%–37%) for deaths occurring within 30 days after an influenza-associated pneumonia/influenza hospitalization, and 19% (95% CI, 4%–31%) for influenza-associated pneumonia/influenza hospitalizations. Because small proportions of deaths, deaths after pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations were associated with influenza virus circulation, we estimated that vaccination prevented 1.6%, 4.8%, and 4.1% of these outcomes, respectively.

Conclusions

By using confounding-reducing techniques with 15 years of provincial-level data including vaccination and health outcomes, we estimated that influenza vaccination prevented ∼4% of influenza-associated hospitalizations and deaths occurring after hospitalizations among older adults in Ontario.     

Influenza vaccination in the elderly: 1. Determinants of acceptance.

In the autumn of 1982 routine annual influenza vaccination was offered, by reminder letters and follow-up telephone calls, to 273 independent elderly individuals registered at a community health clinic in Hamilton, Ont. The demographic and geographic characteristics and the health beliefs of those who either accepted or did not accept the vaccine were compared. Among those who received reminder letters there were no significant differences in the rates of vaccine acceptance according to age, sex, household composition or ease of access to the clinic. The patients who reported having previously experienced side effects from the vaccine and perceived a lack of efficacy of the vaccine were more likely not to accept it this time. Both a lack of effort by health care providers (to promote vaccination) and patient behaviour appeared to contribute to pre-existing low levels of influenza vaccination coverage. Although physicians'' efforts to inform patients about the vaccination clinics resulted in a tripling of the overall rate of acceptance of the vaccine, there remained a "hard core" of almost half the patients who were unwilling to receive the vaccine, apparently because they perceived its risks to outweigh its benefits.     

Live bivalent vaccine for parainfluenza and influenza virus infections

Influenza and human parainfluenza virus infections are of both medical and economical importance. Currently, inactivated vaccines provide suboptimal protection against influenza, and vaccines for human parainfluenza virus infection are not available, underscoring the need for new vaccines against these respiratory diseases. Furthermore, to reduce the burden of vaccination, the development of multivalent vaccines is highly desirable. Thus, to devise a single vaccine that would elicit immune responses against both influenza and parainfluenza viruses, we used reverse genetics to generate an influenza A virus that possesses the coding region for the hemagglutinin/neuraminidase ectodomain of parainfluenza virus instead of the influenza virus neuraminidase. The recombinant virus grew efficiently in eggs but was attenuated in mice. When intranasally immunized with the recombinant vaccine, all mice developed antibodies against both influenza and parainfluenza viruses and survived an otherwise lethal challenge with either of these viruses. This live bivalent vaccine has obvious advantages over combination vaccines, and its method of generation could, in principle, be applied in the development of a "cocktail" vaccine with efficacy against several different infectious diseases.     

Recipients of COVID-19 vaccines face challenges of SARS-CoV-2 variants

The coronavirus disease 19 (COVID-19) has been rampant since 2019, severely affecting global public health, and causing 5.75 million deaths worldwide. So far, many vaccines have been developed to prevent the infection of SARS-CoV-2 virus. However, the emergence of new variants may threat vaccine recipients as they might evade immunological surveillance that depends on the using of anti-SARS-CoV-2 antibody to neutralize the viral particles. Recent studies have found that recipients who received two doses of vaccination plus an additional booster shoot were able to quickly elevate neutralization response and immune response against wild-type SARS-CoV-2 virus and some initially appeared viral variants. In this review, we assessed the real-world effectiveness of different COVID-19 vaccines by population studies and neutralization assays and compared neutralization responses of booster vaccines in vitro. Finally, as the efficacy of COVID-19 vaccine is expected to decline over time, continued vaccination should be considered to achieve a long-term immune protection against coronavirus.