Comparative Reactogenicity of Enhanced Influenza Vaccines in Older Adults

Multivalent H3 COBRA-based influenza vaccine elicits enhanced immune response in a pre-immune elderly ferret model

Influenza viruses cause significant mortality in humans, especially among people 65 years and older. The outbreaks of A(H3N2) influenza viruses or viruses of vaccine-mismatched strains are usually associated with more severe diseases in elderly population. Vaccination is the practical countermeasure for controlling influenza virus infection in humans. However, the immune responses elicited by current influenza vaccines in elderly are not as robust as those responses elicited in younger adults. There is an urgent need for a universal influenza virus vaccine that can induce broadly protective immunity against viral infection in elderly individuals. Currently, influenza virus vaccines that target conserved epitopes on a variety of influenza virus antigens are under evaluation. However, almost all these vaccine candidates are evaluated in adult animal models. In this study, we evaluated Computationally Optimized Broadly Reactive Antigen (COBRA)-based influenza vaccines in elderly ferrets with pre-existing immunity to historical influenza viruses to assess the breadth of vaccine induced protective antibody responses. Vaccination of elderly ferrets with Infectimune® adjuvanted mixtures of COBRA hemagglutinin (HA) and neuraminidase (NA) recombinant protein vaccines elicited robust binding antibodies against all components in the vaccine. Vaccine formulations with multiple H3 COBRA HA components significantly enhanced hemagglutination-inhibition (HAI) activity against H3N2 viruses. In addition, elderly ferrets vaccinated with multivalent COBRA HA and NA vaccines were protected from infection with reduced nasal virus shedding. Overall, a multivalent COBRA HA and NA vaccine may be an effective vaccine strategy to reduce morbidity and mortality in the elderly.

Non-linear effects of age in reporting of adverse events following influenza immunization in Zhejiang, China

BACKGROUND

Previous evidence had suggested age and sex affect the reporting rate of adverse events following immunization (AEFI), but with little exploration of potential their non-linear and interaction effects on AEFIs. Examining these non-linear effects could be beneficial for identifying high-risk populations.

METHODS

Using AEFI records and vaccination data from national passive surveillance system of adverse event following immunization and Zhejiang provincial immunization information system in the 2021-2022 influenza season, respectively. The effects of age and sex on AEFIs were analyzed through the generalized additive model (logistic regression with a smooth term) to estimate non-linear characteristics after adjusting for other co-variables (adopted significance level p < 0.05).

RESULTS

There were 1,259,975 influenza vaccine doses administered and 1304 AEFI records reported during the 2021-2022 influenza season, with a reporting rate of 10.35/10,000 doses. The odds of reporting an AEFI increased from 6 months of age, peaking at about 54 years of age, then gradually declined. The odds of females experiencing AEFIs are higher than that of males. The data model indicated clear effects of age, sex, and their interaction (p < 0.01) on reporting rate of AEFI. Concomitant vaccination and vaccine type were also the impact factors for reporting rate of AEFI.

CONCLUSION

This study revealed a non-linear property in age and the AEFI odds, with a significant interaction and higher reporting rate in females. In addition, the odds of AEFI increased with co-administration compared to separate vaccination.

Evidence base for yearly respiratory virus vaccines: Current status and proposed improved strategies

Annual vaccination is widely recommended for influenza and SARS-CoV-2. In this essay, we analyse and question the prevailing policymaking approach to these respiratory virus vaccines, especially in the United States. Every year, licensed influenza vaccines are reformulated to include specific strains expected to dominate in the season ahead. Updated vaccines are rapidly manufactured and approved without further regulatory requirement of clinical data. Novel vaccines (i.e. new products) typically undergo clinical trials, though generally powered for clinically unimportant outcomes (e.g. lab-confirmed infections, regardless of symptomatology or antibody levels). Eventually, the current and future efficacy of influenza and COVID-19 vaccines against hospitalization or death carries considerable uncertainty. The emergence of highly transmissible SARS-CoV-2 variants and waning vaccine-induced immunity led to plummeting vaccine effectiveness, at least against symptomatic infection, and booster doses have since been widely recommended. No further randomized trials were performed for clinically important outcomes for licensed updated boosters. In both cases, annual vaccine effectiveness estimates are generated by observational research, but observational studies are particularly susceptible to confounding and bias. Well-conducted experimental studies, particularly randomized trials, are necessary to address persistent uncertainties about influenza and COVID-19 vaccines. We propose a new research framework which would render results relevant to the current or future respiratory viral seasons. We demonstrate that experimental studies are feasible by adopting a more pragmatic approach and provide strategies on how to do so. When it comes to implementing policies that seriously impact people's lives, require substantial public resources and/or rely on widespread public acceptance, high evidence standards are desirable.

Immunogenicity of High-Dose Versus MF59-Adjuvanted Versus Standard Influenza Vaccine in Solid Organ Transplant Recipients: The Swiss/Spanish Trial in Solid Organ Transplantation on Prevention of Influenza (STOP-FLU Trial)

BACKGROUND

The immunogenicity of the standard influenza vaccine is reduced in solid-organ transplant (SOT) recipients, so new vaccination strategies are needed in this population.

METHODS

Adult SOT recipients from 9 transplant clinics in Switzerland and Spain were enrolled if they were >3 months after transplantation. Patients were randomized (1:1:1) to a MF59-adjuvanted or a high-dose vaccine (intervention), or a standard vaccine (control), with stratification by organ and time from transplant. The primary outcome was vaccine response rate, defined as a ≥4-fold increase of hemagglutination-inhibition titers to at least 1 vaccine strain at 28 days postvaccination. Secondary outcomes included polymerase chain reaction-confirmed influenza and vaccine reactogenicity.

RESULTS

A total of 619 patients were randomized, 616 received the assigned vaccines, and 598 had serum available for analysis of the primary endpoint (standard, n = 198; MF59-adjuvanted, n = 205; high-dose, n = 195 patients). Vaccine response rates were 42% (84/198) in the standard vaccine group, 60% (122/205) in the MF59-adjuvanted vaccine group, and 66% (129/195) in the high-dose vaccine group (difference in intervention vaccines vs standard vaccine, 0.20; 97.5% confidence interval [CI], .12-1); P < .001; difference in high-dose vs standard vaccine, 0.24 [95% CI, .16-1]; P < .001; difference in MF59-adjuvanted vs standard vaccine, 0.17 [97.5% CI, .08-1]; P < .001). Influenza occurred in 6% of the standard, 5% in the MF59-adjuvanted, and 7% in the high-dose vaccine groups. Vaccine-related adverse events occurred more frequently in the intervention vaccine groups, but most of the events were mild.

CONCLUSIONS

In SOT recipients, use of an MF59-adjuvanted or a high-dose influenza vaccine was safe and resulted in a higher vaccine response rate.

CLINICAL TRIALS REGISTRATION

Clinicaltrials.gov NCT03699839.

Predictive Value of Reactogenicity for Anti-SARS-CoV-2 Antibody Response in mRNA-1273 Recipients: A Multicenter Prospective Cohort Study

Messenger RNA (mRNA) vaccination was developed to mitigate the coronavirus disease 2019 pandemic. However, data on antibody kinetics and factors influencing these vaccines' immunogenicity are limited. We conducted a prospective study on healthy young adults who received two doses of the mRNA-1273 vaccine at 28-day intervals. After each dose, adverse events were prospectively evaluated, and blood samples were collected. The correlation between humoral immune response and reactogenicity after vaccination was determined. In 177 participants (19-55 years), the geometric mean titers of anti-S IgG antibody were 178.07 and 4409.61 U/mL, while those of 50% neutralizing titers were 479.95 and 2851.67 U/mL four weeks after the first and second vaccine doses, respectively. Anti-S IgG antibody titers were not associated with local reactogenicity but were higher in participants who experienced systemic adverse events (headache and muscle pain). Antipyretic use was an independent predictive factor of a robust anti-SARS-CoV-2 antibody response after receiving both vaccine doses. Systemic reactogenicity after the first dose influenced antibody response after the second dose. In conclusion, mRNA-1273 induced a robust antibody response in healthy young adults. Antipyretic use did not decrease the anti-SARS-CoV-2 antibody response after mRNA-1273 vaccination.

Health behaviors are largely not predictive of adverse events following influenza vaccination

BACKGROUND

Identifying health behaviors associated with adverse events following immunization (AEFI) could identify intervention targets for AEFI prevention.

METHODS

University employees receiving an influenza vaccination (n = 1301) completed a series of online surveys for health behaviors including sleep, exercise, dietary intake, and smoking habits, and emotional state (baseline), and for indications of AEFI (three days post-vaccination) and influenza-like illness (ILI) symptoms (fortnightly follow-up for 4 months).

RESULTS

29.9% of participants reported an AEFI and 46.0% reported experiencing ILI during follow-up. Multivariate logistic regression revealed usual sleep duration was associated with AEFI (odds ratio 1.20, 95% confidence interval 1.03-1.41), increasing with each hour of sleep. ILI was associated with reporting AEFI (1.70, 1.24-2.33), increasing BMI (1.03, 1.00-1.06) and survey response frequency (1.13, 1.04-1.22), and decreased with better usual sleep quality (0.96, 0.92-1.00) and with increasing age (0.98, 0.96-1.00). Sex stratification revealed no significant predictors of AEFI for either sex; in women, experiencing AEFI increased likelihood of ILI (1.88, 1.25-2.85) and in men, survey completion frequency increased ILI likelihood (1.19, 1.05-1.36).

CONCLUSIONS

Our study suggests modifying health behaviors would not alter AEFI risk and reactogenicity may signal weaker immunogenicity but confirmation through objective measures is warranted.

National safety surveillance of quadrivalent recombinant influenza vaccine in Taiwan during NH 20/21

BACKGROUND

During the COVID-19 pandemic, the need for influenza vaccine significantly increased in the initial weeks of the 2020-2021 influenza vaccination campaign season in Taiwan. To meet this demand, the Taiwanese government therefore purchased additional influenza vaccines via special import, including 350,000 doses of quadrivalent recombinant influenza vaccines (RIV4, Flublok Quadrivalent). Approved in the United States since 2016, there were limited numbers of published studies regarding RIV4 outside America. We utilized the national passive surveillance system consisting adverse event (AE) reports following RIV4 immunization to describe its safety profiles in Taiwan.

METHODS

We obtained the database from the Taiwan National Adverse Drugs Reactions Reporting System and collected reports from January 2021 to July 2021, which was at least one month after RIV4 immunization. AE reporting rates were calculated based on the total administered doses.

RESULTS

Eight AEs were reported among 200,287 administered doses, which led to a reporting rate of 3.99 AEs per 100,000 doses administered. The mean age of the reported individuals were 47.53 years, and women (75%) were the predominant gender. Most adverse events started within the first day after immunization, with one reported as starting 4 days after vaccination. Among the 8 cases, 75% (n = 6) were non-serious and the most common symptoms were erythematous skin rashes with pruritus. Two cases were listed as serious based on the criteria of "other clinically significant medical conditions", but neither was judged to have a causal relationship with RIV4 immunization.

CONCLUSION

The Taiwan national passive surveillance data supported the safety profiles of RIV4 in Taiwan population.

The safety of co-administration of Bacille Calmette-Guérin (BCG) and influenza vaccines

BACKGROUND

With the emergence of novel vaccines and new applications for older vaccines, co-administration is increasingly likely. The immunomodulatory effects of BCG could theoretically alter the reactogenicity of co-administered vaccines. Using active surveillance in a randomised controlled trial, we aimed to determine whether co-administration of BCG vaccination changes the safety profile of influenza vaccination.

METHODS

Participants who received influenza vaccine alone (Influenza group) were compared with those who also received BCG-Denmark vaccine in the contralateral arm (Influenza+BCG group). Data on the influenza vaccination site were collected using serial questionnaires and active follow-up for 3 months post vaccination.

RESULTS

Of 1351 participants in the Influenza+BCG group and 1418 participants in the Influenza group, 2615 (94%) provided influenza vaccine safety data. There was no significant difference in the proportion of participants with any local adverse reaction between the Influenza+BCG group and the Influenza group (918/1293 [71.0%] versus (906/1322 [68.5%], p = 0.17). The proportion of participants reporting any pain, erythema and tenderness at the influenza vaccination site were similar in both groups. Swelling was less frequent (81/1293 [6.3%] versus 119/1322 (9.0%), p = 0.01) and the maximal diameter of erythema was smaller (mean 1.8 cm [SD 2.0] versus 3.0 cm [SD 2.5], p<0.001) in the Influenza+BCG group. Sixteen participants reported serious adverse events: 9 participants in the Influenza+BCG group and 7 in the Influenza group.

CONCLUSIONS

Adverse events following influenza vaccination are not increased when BCG is co-administered.

Correlation of Immunogenicity and Reactogenicity of BNT162b2 and CoronaVac SARS-CoV-2 Vaccines

COVID-19 infection is a global health issue, and vaccination is the main strategy to control this pandemic. In this study, 189 participants received BNT162b2 or CoronaVac vaccine, and 133 of them recorded adverse events (AEs) daily for 4 weeks after vaccination. Their neutralizing antibody against SARS-CoV-2 was determined with live virus microneutralization (vMN) assay. The vMN geometric mean titer (GMT) on day 56 was 129.9 (95% confidence interval [CI],108.6 to 155.2) in the BNT162b2 group and 13.1 (95% CI, 11.2 to 15.3) in the CoronaVac group. Day 56 vMN GMT was 147.9 (95% CI, 118.9 to 184.1) in females and 129.9 (95% CI, 108.6 to 155.2) in males receiving BNT162b2, while it was 14.0 (95% CI, 11.6 to 17.0) in females and 11.4 (95% CI, 8.7 to 15.0) in males receiving CoronaVac. Injection site pain (88.8%) and redness (77.5%) were the most commonly BNT162b2-related AEs, and injection site pain (37.7%) and tiredness (26.4%) were more frequent in the CoronaVac group. Women showed a higher frequency of headache (45.7% versus 29.4%) and joint pain (26.1 versus 14.7%) than men in BTN162b2 group. Headache (26.5% versus 0%) and tiredness (38.2% versus 5.3%) were more common in women than in men vaccinated with CoronaVac. No correlation between any AE and antibody response was observed in BNT162b2 or CoronaVac platforms. After taking the gender factor into account, in the BNT162b2 group, a low correlation between day 21 vMN titer and redness (rho = 0.34) or itching (rho = 0.32) was presented in females, and a low correlation between day 56 vMN titer and fever (rho = 0.35) was presented in males. Taken together, AEs could have a low correlation with BNT162b2 vaccine response.

IMPORTANCE Effective vaccines against SARS-CoV-2 are vital tools for containing the COVID-19 pandemic by increasing population immunity. While currently available vaccines can elicit antibody response against SARS-CoV-2 with high efficacy, the associated side effects may cause vaccine hesitancy. Our work is important in that we have thoroughly analyzed the correlation between immunogenicity and reactogenicity of two COVID-19 vaccines (BNT162b2 and CoronaVac) in the study. Our results showed that women had higher levels of neutralizing antibodies than men after receiving BNT162b2 or CoronaVac. Furthermore, a low correlation was observed between day 21 vMN titer and local reactions (redness and itching) in females, as well as between day 56 vMN titer and fever in males receiving BNT162b2. Thus, common side effects are not always a negative impact of vaccination but may serve as an indicator of immunogenicity of vaccines. Our study may help in increasing the public’s acceptance and confidence over COVID-19 vaccination and ultimately achieving the goal of containing COVID-19 pandemic.

Adverse events following influenza immunization: understanding the role of age and sex interactions

BACKGROUND

Reduction of adverse events following immunization (AEFI) could improve vaccine uptake. Evidence suggests sex and age affect AEFI rates but, with limited understanding of their interaction, groups at higher risk for adverse reaction cannot be identified.

RESEARCH DESIGN AND METHODS

Using deidentified data (n = 308,481) from Australians receiving influenza vaccinations in the 2020 calendar year, we analyzed the effects of independent predictors (i.e. age and sex), on experiencing an AEFI using logistic regression generalized additive modeling to capture any nonlinear relationships and adjusting for vaccine brand and concomitant vaccination.

RESULTS

The overall reaction rate was 5.5%. Modeling revealed significant effects of age (p < 0.001), sex (p < 0.001), and age × sex (p < 0.001). Females were more likely than males to experience AEFIs between 7.5 and 87.5 years of age and exhibited peak odds at about 53 years, while peak odds for males occurred in infancy.

CONCLUSION

The results suggest there is a need for targeting AEFI reduction in females, particularly in 30-70-year-olds, to improve the vaccination experience. The results further suggest that reducing concomitant vaccination and choosing less reactogenic vaccine brands could reduce risk of AEFI, however, retaining concomitant vaccination may optimize vaccine uptake.

Does a lack of vaccine side effects correlate with reduced BNT162b2 mRNA vaccine response among healthcare workers and nursing home residents?

BACKGROUND

The BNT162b2 SARS-CoV-2 mRNA vaccination has mitigated the burden of COVID-19 among residents of long-term care facilities considerably, despite being excluded from the vaccine trials. Data on reactogenicity (vaccine side effects) in this population are limited.

AIMS

To assess reactogenicity among nursing home (NH) residents. To provide a plausible proxy for predicting vaccine response among this population.

METHODS

We enrolled and sampled NH residents and community-dwelling healthcare workers who received the BNT162b2 mRNA vaccine, to assess local or systemic reactogenicity and antibody levels (immunogenicity).

RESULTS

NH residents reported reactions at a much lower frequency and lesser severity than the community-dwelling healthcare workers. These reactions were mild and transient with all subjects experiencing more local than systemic reactions. Based on our reactogenicity and immunogenicity data, we developed a linear regression model predicting log-transformed anti-spike, anti-receptor-binding domain (RBD), and neutralizing titers, with a dichotomous variable indicating the presence or absence of reported reactions which revealed a statistically significant effect, with estimated shifts in log-transformed titers ranging from 0.32 to 0.37 (all p < 0.01) indicating greater immunogenicity in subjects with one or more reported reactions of varying severity.

DISCUSSION

With a significantly lower incidence of post-vaccination reactions among NH residents as reported in this study, the BNT162b2 mRNA vaccine appears to be well-tolerated among this vulnerable population. If validated in larger populations, absence of reactogenicity could help guide clinicians in prioritizing vaccine boosters.

CONCLUSIONS

Reactogenicity is significantly mild among nursing home residents and overall, subjects who reported post-vaccination reactions developed higher antibody titers.

Repeated influenza vaccination provides cumulative protection from distinct H3N2 viruses

OBJECTIVES

Current inactivated influenza vaccines provide suboptimal protection against antigenic drift, and repeated annual vaccinations shape antibody specificity but the effect on protection from infection is not well understood.

METHODS

We studied the effects of cumulative and staggered vaccinations in mice to determine the effect of influenza vaccination on protection from infection and immune quality.

RESULTS

We found that the timing of vaccination and antigenic change impacted the quality of immune responses. When mice received two different H3N2 strains (A/Hong Kong/4801/2014 and A/Singapore/INFIMH-16-0019/2016) by staggered timing of vaccination, there were higher H3HA antibody and B-cell memory responses than four cumulative vaccinations or when two vaccinations were successive. Interestingly, after challenge with a lethal-drifted H3N2 virus (A/Hong Kong/1/1968), mice with staggered vaccination were unable to produce high titres of antibodies specific to the challenge strain compared to other vaccination regimens because of high levels of vaccine-specific cross-reactive antibodies. All vaccination regimens resulted in protection, in terms of viral loads and survival, from lethal challenge, while lung IL-6 and inflammation were lowest in staggered or cumulative vaccination groups, indicating further advantage.

CONCLUSION

Our findings help justify influenza vaccination policies that currently recommend repeat vaccination in infants and annual seasonal vaccination, with no evidence for impaired immunity by repeated seasonal vaccination.

Safety of vaccines used for routine immunization in the United States: An updated systematic review and meta-analysis

BACKGROUND

Understanding the safety of vaccines is critical to inform decisions about vaccination. Our objective was to conduct a systematic review of the safety of vaccines recommended for children, adults, and pregnant women in the United States.

METHODS

We searched the literature in November 2020 to update a 2014 Agency for Healthcare Research and Quality review by integrating newly available data. Studies of vaccines that used a comparator and reported the presence or absence of key adverse events were eligible. Adhering to Evidence-based Practice Center methodology, we assessed the strength of evidence (SoE) for all evidence statements. The systematic review is registered in PROSPERO (CRD42020180089).

RESULTS

Of 56,603 reviewed citations, 338 studies reported in 518 publications met inclusion criteria. For children, SoE was high for no increased risk of autism following measles, mumps, and rubella (MMR) vaccine. SoE was high for increased risk of febrile seizures with MMR. There was no evidence of increased risk of  intussusception with rotavirus vaccine at the latest follow-up (moderate SoE), nor of diabetes (high SoE). There was no evidence of increased risk or insufficient evidence for key adverse events for newer vaccines such as 9-valent human papillomavirus and meningococcal B vaccines. For adults, there was no evidence of increased risk (varied SoE) or insufficient evidence for key adverse events for the new adjuvanted inactivated influenza vaccine and recombinant adjuvanted zoster vaccine. We found no evidence of increased risk (varied SoE) for key adverse events among pregnant women following tetanus, diphtheria, and acellular pertussis vaccine, including stillbirth (moderate SoE).

CONCLUSIONS

Across a large body of research we found few associations of vaccines and serious key adverse events; however, rare events are challenging to study. Any adverse events should be weighed against the protective benefits that vaccines provide.

Vaccines for older adults

The proportion of the global population aged 65 and older is rapidly increasing. Infections in this age group, most recently with SARS-CoV-2, cause substantial morbidity and mortality. Major improvements have been made in vaccines for older people, either through the addition of novel adjuvants-as in the new recombinant zoster vaccine and an adjuvanted influenza vaccine-or by increasing antigen concentration, as in influenza vaccines. In this article we review improvements in immunization for the three most important vaccine preventable diseases of aging. The recombinant zoster vaccine has an efficacy of 90% that is minimally affected by the age of the person being vaccinated and persists for more than four years. Increasing antigen dose or inclusion of adjuvant has improved the immunogenicity of influenza vaccines in older adults, although the relative effectiveness of the enhanced influenza vaccines and the durability of the immune response are the focus of ongoing clinical trials. Conjugate and polysaccharide pneumococcal vaccines have similar efficacy against invasive pneumococcal disease and pneumococcal pneumonia caused by vaccine serotypes in older adults. Their relative value varies by setting, depending on the prevalence of vaccine serotypes, largely related to conjugate vaccine coverage in children. Improved efficacy will increase public confidence and uptake of these vaccines. Co-administration of these vaccines is feasible and important for maximal uptake in older people. Development of new vaccine platforms has accelerated following the arrival of SARS-CoV-2, and will likely result in new vaccines against other pathogens in the future.