Assessment of potential adverse events following the 2022-2023 seasonal influenza vaccines among U.S. adults aged 65 years and older

BACKGROUND

While safety of influenza vaccines is well-established, some studies have suggested potential associations between influenza vaccines and certain adverse events (AEs). This study examined the safety of the 2022-2023 influenza vaccines among U.S. adults ≥ 65 years.

METHODS

A self-controlled case series compared incidence rates of anaphylaxis, encephalitis/encephalomyelitis, Guillain-Barré Syndrome (GBS), and transverse myelitis following 2022-2023 seasonal influenza vaccinations (i.e., any, high-dose or adjuvanted) in risk and control intervals among Medicare beneficiaries ≥ 65 years. We used conditional Poisson regression to estimate incidence rate ratios (IRRs) and 95 % confidence intervals (CIs) adjusted for event-dependent observation time and seasonality. Analyses also accounted for uncertainty from outcome misclassification where feasible. For AEs with any statistically significant associations, we stratified results by concomitant vaccination status.

RESULTS

Among 12.7 million vaccine recipients, we observed 76 anaphylaxis, 276 encephalitis/encephalomyelitis, 134 GBS and 75 transverse myelitis cases. Only rates of anaphylaxis were elevated in risk compared to control intervals. With all adjustments, an elevated, but non-statistically significant, anaphylaxis rate was observed following any (IRR: 2.40, 95% CI: 0.96-6.03), high-dose (IRR: 2.31, 95% CI: 0.67-7.91), and adjuvanted (IRR: 3.28, 95% CI: 0.71-15.08) influenza vaccination; anaphylaxis IRRs were 2.54 (95% CI: 0.49-13.05) and 1.64 (95% CI: 0.38-7.05) for persons with and without concomitant vaccination, respectively.

CONCLUSIONS

Rates of encephalitis/encephalomyelitis, GBS, or transverse myelitis were not elevated following 2022-2023 seasonal influenza vaccinations among U.S. adults ≥ 65 years. There was an increased rate of anaphylaxis following influenza vaccination that may have been influenced by concomitant vaccination.

Effectiveness of BNT162b2 COVID-19 primary series vaccination in children aged 5-17 years in the United States: a cohort study

BACKGROUND

COVID-19 vaccines are authorized for use in children in the United States; real-world assessment of vaccine effectiveness in children is needed. This study's objective was to estimate the effectiveness of receiving a complete primary series of monovalent BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine in US children.

METHODS

This cohort study identified children aged 5-17 years vaccinated with BNT162b2 matched with unvaccinated children. Participants and BNT162b2 vaccinations were identified in Optum and CVS Health insurance administrative claims databases linked with Immunization Information System (IIS) COVID-19 vaccination records from 16 US jurisdictions between December 11, 2020, and May 31, 2022 (end date varied by database and IIS). Vaccinated children were followed from their first BNT162b2 dose and matched to unvaccinated children on calendar date, US county of residence, and demographic and clinical factors. Censoring occurred if vaccinated children failed to receive a timely dose 2 or if unvaccinated children received any dose. Two COVID-19 outcome definitions were evaluated: COVID-19 diagnosis in any medical setting and COVID-19 diagnosis in hospitals/emergency departments (EDs). Propensity score-weighted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated with Cox proportional hazards models, and vaccine effectiveness (VE) was estimated as 1 minus HR. VE was estimated overall, within age subgroups, and within variant-specific eras. Sensitivity, negative control, and quantitative bias analyses evaluated various potential biases.

RESULTS

There were 453,655 eligible vaccinated children one-to-one matched to unvaccinated comparators (mean age 12 years; 50% female). COVID-19 hospitalizations/ED visits were rare in children, regardless of vaccination status (Optum, 41.2 per 10,000 person-years; CVS Health, 44.1 per 10,000 person-years). Overall, vaccination was associated with reduced incidence of any medically diagnosed COVID-19 (meta-analyzed VE = 38% [95% CI, 36-40%]) and hospital/ED-diagnosed COVID-19 (meta-analyzed VE = 61% [95% CI, 56-65%]). VE estimates were lowest among children 5-11 years and during the Omicron-variant era.

CONCLUSIONS

Receipt of a complete BNT162b2 vaccine primary series was associated with overall reduced medically diagnosed COVID-19 and hospital/ED-diagnosed COVID-19 in children; observed VE estimates differed by age group and variant era.

REGISTRATION

The study protocol was publicly posted on the BEST Initiative website ( https://bestinitiative.org/wp-content/uploads/2022/03/C19-VX-Effectiveness-Protocol_2022_508.pdf ).

Safety of Ancestral Monovalent BNT162b2, mRNA-1273, and NVX-CoV2373 COVID-19 Vaccines in US Children Aged 6 Months to 17 Years

Importance

Active monitoring of health outcomes after COVID-19 vaccination provides early detection of rare outcomes that may not be identified in prelicensure trials.

Objective

To conduct near-real-time monitoring of health outcomes after COVID-19 vaccination in the US pediatric population.

Design, Setting, and Participants

This cohort study evaluated 21 prespecified health outcomes after exposure before early 2023 to BNT162b2, mRNA-1273, or NVX-CoV2373 ancestral monovalent COVID-19 vaccines in children aged 6 months to 17 years by applying a near-real-time monitoring framework using health care data from 3 commercial claims databases in the US (Optum [through April 2023], Carelon Research [through March 2023], and CVS Health [through February 2023]). Increased rates of each outcome after vaccination were compared with annual historical rates from January 1 to December 31, 2019, and January 1 to December 31, 2020, as well as between April 1 and December 31, 2020.

Exposure

Receipt of an ancestral monovalent BNT162b2, mRNA-1273, or NVX-CoV2373 COVID-19 vaccine dose identified through administrative claims data linked with Immunization Information Systems data.

Main Outcomes and Measures

Twenty-one prespecified health outcomes, of which 15 underwent sequential testing and 6 were only monitored descriptively due to lack of historical rates.

Results

Among 4 102 016 vaccinated enrollees aged 6 months to 17 years, 2 058 142 (50.2%) were male and 3 901 370 (95.1%) lived in an urban area. Thirteen of 15 sequentially tested outcomes did not meet the threshold for a statistical signal. Statistical signals were detected for myocarditis or pericarditis after BNT162b2 vaccination in children aged 12 to 17 years and seizure after vaccination with BNT162b2 and mRNA-1273 in children aged 2 to 4 or 5 years. However, in post hoc sensitivity analyses, a statistical signal for seizure was observed only after mRNA-1273 when 2019 background rates were selected; no statistical signal was observed when 2022 rates were selected.

Conclusions and Relevance

In this cohort study of pediatric enrollees across 3 commercial health insurance databases, statistical signals detected for myocarditis or pericarditis after BNT162b2 (ages 12-17 years) were consistent with previous reports, and seizures after BNT162b2 (ages 2-4 years) and mRNA-1273 vaccinations (ages 2-5 years) should be further investigated in a robust epidemiologic study with confounding adjustment. The US Food and Drug Administration concludes that the known and potential benefits of COVID-19 vaccination outweigh the known and potential risks of COVID-19 infection.

Incidence rates of thrombosis with thrombocytopenia syndrome (TTS) among adults in United States commercial and Medicare claims databases, 2017-2020

BACKGROUND

Increased risk of thrombosis with thrombocytopenia syndrome (TTS) following adenovirus vector-based COVID-19 vaccinations has been identified in passive surveillance systems. TTS incidence rates (IRs) in the United States (U.S.) are needed to contextualize reports following COVID-19 vaccination.

METHODS

We estimated annual and monthly IRs of overall TTS, common site TTS, and unusual site TTS for adults aged 18-64 years in Carelon Research and MarketScan commercial claims (2017-Oct 2020), CVS Health and Optum commercial claims (2019-Oct 2020), and adults aged ≥ 65 years using CMS Medicare claims (2019-Oct 2020); IRs were stratified by age, sex, and race/ethnicity (CMS Medicare).

RESULTS

Across data sources, annual IRs for overall TTS were similar between Jan-Dec 2019 and Jan-Oct 2020. Rates were higher in Medicare (IRs: 370.72 and 365.63 per 100,000 person-years for 2019 and 2020, respectively) than commercial data sources (MarketScan IRs: 24.21 and 24.06 per 100,000 person-years; Optum IRs: 32.60 and 31.29 per 100,000 person-years; Carelon Research IRs: 24.46 and 26.16 per 100,000 person-years; CVS Health IRs: 30.31 and 30.25 per 100,000 person-years). Across years and databases, common site TTS IRs increased with age and were higher among males. Among adults aged ≥ 65 years, the common site TTS IR was highest among non-Hispanic black adults. Annual unusual site TTS IRs ranged between 2.02 and 3.04 (commercial) and 12.49 (Medicare) per 100,000 person-years for Jan-Dec 2019; IRs ranged between 1.53 and 2.67 (commercial) and 11.57 (Medicare) per 100,000 person-years for Jan-Oct 2020. Unusual site TTS IRs were higher in males and increased with age in commercial data sources; among adults aged ≥ 65 years, IRs decreased with age and were highest among non-Hispanic American Indian/Alaska native adults.

CONCLUSION

TTS IRs were generally similar across years, higher for males, and increased with age. These rates may contribute to surveillance of post-vaccination TTS.

Stroke Risk After COVID-19 Bivalent Vaccination Among US Older Adults

Importance

In January 2023, the US Centers for Disease Control and Prevention and the US Food and Drug Administration noted a safety concern for ischemic stroke among adults aged 65 years or older who received the Pfizer-BioNTech BNT162b2; WT/OMI BA.4/BA.5 COVID-19 bivalent vaccine.

Objective

To evaluate stroke risk after administration of (1) either brand of the COVID-19 bivalent vaccine, (2) either brand of the COVID-19 bivalent plus a high-dose or adjuvanted influenza vaccine on the same day (concomitant administration), and (3) a high-dose or adjuvanted influenza vaccine.

Design, Setting, and Participants

Self-controlled case series including 11 001 Medicare beneficiaries aged 65 years or older who experienced stroke after receiving either brand of the COVID-19 bivalent vaccine (among 5 397 278 vaccinated individuals). The study period was August 31, 2022, through February 4, 2023.

Exposures

Receipt of (1) either brand of the COVID-19 bivalent vaccine (primary) or (2) a high-dose or adjuvanted influenza vaccine (secondary).

Main Outcomes and Measures

Stroke risk (nonhemorrhagic stroke, transient ischemic attack, combined outcome of nonhemorrhagic stroke or transient ischemic attack, or hemorrhagic stroke) during the 1- to 21-day or 22- to 42-day risk window after vaccination vs the 43- to 90-day control window.

Results

There were 5 397 278 Medicare beneficiaries who received either brand of the COVID-19 bivalent vaccine (median age, 74 years [IQR, 70-80 years]; 56% were women). Among the 11 001 beneficiaries who experienced stroke after receiving either brand of the COVID-19 bivalent vaccine, there were no statistically significant associations between either brand of the COVID-19 bivalent vaccine and the outcomes of nonhemorrhagic stroke, transient ischemic attack, nonhemorrhagic stroke or transient ischemic attack, or hemorrhagic stroke during the 1- to 21-day or 22- to 42-day risk window vs the 43- to 90-day control window (incidence rate ratio [IRR] range, 0.72-1.12). Among the 4596 beneficiaries who experienced stroke after concomitant administration of either brand of the COVID-19 bivalent vaccine plus a high-dose or adjuvanted influenza vaccine, there was a statistically significant association between vaccination and nonhemorrhagic stroke during the 22- to 42-day risk window for the Pfizer-BioNTech BNT162b2; WT/OMI BA.4/BA.5 COVID-19 bivalent vaccine (IRR, 1.20 [95% CI, 1.01-1.42]; risk difference/100 000 doses, 3.13 [95% CI, 0.05-6.22]) and a statistically significant association between vaccination and transient ischemic attack during the 1- to 21-day risk window for the Moderna mRNA-1273.222 COVID-19 bivalent vaccine (IRR, 1.35 [95% CI, 1.06-1.74]; risk difference/100 000 doses, 3.33 [95% CI, 0.46-6.20]). Among the 21 345 beneficiaries who experienced stroke after administration of a high-dose or adjuvanted influenza vaccine, there was a statistically significant association between vaccination and nonhemorrhagic stroke during the 22- to 42-day risk window (IRR, 1.09 [95% CI, 1.02-1.17]; risk difference/100 000 doses, 1.65 [95% CI, 0.43-2.87]).

Conclusions and Relevance

Among Medicare beneficiaries aged 65 years or older who experienced stroke after receiving either brand of the COVID-19 bivalent vaccine, there was no evidence of a significantly elevated risk for stroke during the days immediately after vaccination.

Real-world Effectiveness of mRNA COVID-19 Vaccines Among US Nursing Home Residents Aged ≥65 Years in the Pre-Delta and High Delta Periods

Background

Long-term care residents were among the most vulnerable during the COVID-19 pandemic. We estimated vaccine effectiveness of mRNA COVID-19 vaccines in Medicare nursing home residents aged ≥65 years during pre-Delta and high Delta periods.

Methods

We conducted a retrospective cohort study from 13 December 2020 to 20 November 2021 using Medicare claims data. Exposures included 2 and 3 doses of Pfizer-BioNTech and Moderna COVID-19 vaccines. We used inverse probability weighting and Cox proportional hazards models to estimate absolute and relative vaccine effectiveness.

Results

Two-dose vaccine effectiveness against COVID-19-related death was 69.8% (95% CI, 65.9%‒73.3%) during the pre-Delta period and 55.7% (49.5%‒61.1%) during the high Delta period, without adjusting for time since vaccination. We observed substantial waning of effectiveness from 65.1% (54.2%‒73.5%) within 6 months from second-dose vaccination to 45.2% (30.6%‒56.7%) ≥6 months after second-dose vaccination in the high Delta period. Three doses provided 88.7% (73.5%‒95.2%) vaccine effectiveness against death, and the incremental benefit of 3 vs 2 doses was 74.6% (40.4%‒89.2%) during high Delta. Among beneficiaries with a prior COVID-19 infection, 3-dose vaccine effectiveness for preventing death was 78.6% (50.0%‒90.8%), and the additional protection of 3 vs 2 doses was 70.0% (30.1%‒87.1%) during high Delta. Vaccine effectiveness estimates against less severe outcomes (eg, infection) were lower.

Conclusions

This nationwide real-world study demonstrated that mRNA COVID-19 vaccines provided substantial protection against COVID-19-related death. Two-dose protection waned after 6 months. Third doses during the high Delta period provided significant additional protection for individuals with or without a prior COVID-19 infection.

Effectiveness of monovalent COVID-19 booster/additional vaccine doses in the United States

Background

Monovalent booster/additional doses of COVID-19 vaccines were first authorized in August 2021 in the United States. We evaluated the real-world effectiveness of receipt of a monovalent booster/additional dose of COVID-19 vaccine compared with receiving a primary vaccine series without a booster/additional dose.

Methods

Cohorts of individuals receiving a COVID-19 booster/additional dose after receipt of a complete primary vaccine series were identified in 2 administrative insurance claims databases (Optum, CVS Health) supplemented with state immunization information system data between August 2021 and March 2022. Individuals with a complete primary series but without a booster/additional dose were one-to-one matched to boosted individuals on calendar date, geography, and clinical factors. COVID-19 diagnoses were identified in any medical setting, or specifically in hospitals/emergency departments (EDs). Propensity score-weighted hazards ratios (HRs) and 95% confidence intervals (CI) were estimated with Cox proportional hazards models; vaccine effectiveness (VE) was estimated as 1 minus the HR by vaccine brand overall and within subgroups of variant-specific eras, immunocompromised status, and homologous/heterologous booster status.

Results

Across both data sources, we identified 752,165 matched pairs for BNT162b2, 410,501 for mRNA-1273, and 11,398 for JNJ-7836735. For any medically diagnosed COVID-19, meta-analyzed VE estimates for BNT162b2, mRNA-1273, and JNJ-7836735, respectively, were: BNT162b2, 54% (95% CI, 53%-56%); mRNA-1273, 58% (95% CI, 56%-59%); JNJ-7836735, 34% (95% CI, 23%-44%). For hospital/ED-diagnosed COVID-19, VE estimates ranged from 70% to 76%. VE was generally lower during the Omicron era than the Delta era and for immunocompromised individuals. There was little difference observed by homologous or heterologous booster status.

Conclusion

The original, monovalent booster/additional doses were reasonably effective in real-world use among the populations for which they were indicated during the study period. Additional studies may be informative in the future as new variants emerge and new vaccines become available.Registration: The study protocol was publicly posted on the BEST Initiative website (https://bestinitiative.org/wp-content/uploads/2022/03/C19-VX-Effectiveness-Protocol_2022_508.pdf).

Risk of Severe COVID-19 in Prevalent Users of Alpha-1 Adrenergic Receptor Antagonists: A National Case-Control Study of Medicare Beneficiaries

BACKGROUND

Alpha-1 adrenergic receptor antagonists prevent cytokine storm in mouse sepsis models. This led to the hypothesis that alpha-1 blockers may prevent severe coronavirus disease 2019 (COVID-19), which is characterized by hypercytokinemia and progressive respiratory failure.

METHODS

We performed an observational case-control study in male Medicare beneficiaries aged 65 years or older, with or without benign prostatic hyperplasia (BPH), and treated with alpha-1 receptor blockers or 5-alpha reductase inhibitors. Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were estimated for outcomes of uncomplicated and severe COVID-19 hospitalization (intensive care unit admission, invasive mechanical ventilation, or death).

RESULTS

There were 20,963 cases of hospitalized COVID-19 matched to 101,161 controls on calendar date and neighborhood of residence. In the primary analysis (males with BPH), there was no difference in risk of uncomplicated COVID-19 hospitalization (aOR 1.08, 95% CI 0.996-1.17) or hospitalization with severe complications (aOR 0.97, 95% CI 0.88-1.08). In the secondary analysis (males with or without BPH), the corresponding aORs were 1.02 (95% CI, 0.96-1.09) (uncomplicated) and 0.99 (95% CI, 0.91-1.07) (complicated), respectively. Subgroup and sensitivity analyses yielded similar results. Of note, there was no difference in risk of severe COVID-19 hospitalization when comparing non-selective vs selective alpha-1 blocker use (aOR 0.98, 95% CI 0.86-1.10), higher- vs lower-dose alpha-1 blocker use (aOR 0.96, 95% CI 0.86-1.08), or current vs remote alpha-1 blocker use (aOR 1.04, 95% CI 0.91-1.18).

CONCLUSIONS

Prevalent use of alpha-1 receptor blockers was not associated with a protective or harmful effect on risk of uncomplicated or severe hospitalized COVID-19.

HIV risk behavior profiles among men who have sex with men interested in donating blood: Findings from the Assessing Donor Variability and New Concepts in Eligibility study

BACKGROUND

Individual risk assessment allows donors to be evaluated based on their own behaviors. Study objectives were to assess human immunodeficiency virus (HIV) risk behaviors in men who have sex with men (MSM) and estimate the proportion of the study population who would not be deferred for higher risk HIV sexual behaviors.

STUDY DESIGN AND METHODS

Cross-sectional survey and biomarker assessment were conducted in eight U.S. cities. Participants were sexually active MSM interested in blood donation aged 18-39 years, assigned male sex at birth. Participants completed surveys during two study visits to define eligibility, and self-reported sexual and HIV prevention behaviors. Blood was drawn at study visit 1 and tested for HIV and the presence of tenofovir, one of the drugs in oral HIV pre-exposure prophylaxis (PrEP). Associations were assessed between HIV infection status or HIV PrEP use and behaviors, including sex partners, new partners, and anal sex.

RESULTS

A total of 1566 MSM completed the visit 1 questionnaire and blood draw and 1197 completed the visit 2 questionnaire. Among 1562 persons without HIV, 789 (50.4%) were not taking PrEP. Of those not taking PrEP, 66.2% reported one sexual partner or no anal sex and 69% reported no new sexual partners or no anal sex with a new partner in the past 3 months.

CONCLUSION

The study found that questions were able to identify sexually active, HIV-negative MSM who report lower risk sexual behaviors. About a quarter of enrolled study participants would be potentially eligible blood donors using individual risk assessment questions.

Benefit-risk assessment of Covid-19 vaccine, MRNA (MRNA-1273) for males age 18-64 years

Since the authorization of the Moderna mRNA COVID-19 vaccine, real-world evidence has indicated its effectiveness in preventing COVID-19 cases. However, increased cases of mRNA vaccine-associated myocarditis/pericarditis have been reported, predominantly in young adults and adolescents. The Food and Drug Administration conducted a benefit-risk assessment to inform the review of the Biologics License Application for use of the Moderna vaccine among individuals ages 18 and older. We modeled the benefit-risk per million individuals who receive two complete doses of the vaccine. Benefit endpoints were vaccine-preventable COVID-19 cases, hospitalizations, intensive care unit (ICU) admissions, and deaths. The risk endpoints were vaccine-related myocarditis/pericarditis cases, hospitalizations, ICU admissions, and deaths. The analysis was conducted on the age-stratified male population due to data signals and previous work showing males to be the main risk group. We constructed six scenarios to evaluate the impact of uncertainty associated with pandemic dynamics, vaccine effectiveness (VE) against novel variants, and rates of vaccine-associated myocarditis/pericarditis cases on the model results. For our most likely scenario, we assumed the US COVID-19 incidence was for the week of December 25, 2021, with a VE of 30% against cases and 72% against hospitalization with the Omicron-dominant strain. Our source for estimating vaccine-attributable myocarditis/pericarditis rates was FDA's CBER Biologics Effectiveness and Safety (BEST) System databases. Overall, our results supported the conclusion that the benefits of the vaccine outweigh its risks. Remarkably, we predicted vaccinating one million 18-25 year-old males would prevent 82,484 cases, 4,766 hospitalizations, 1,144 ICU admissions, and 51 deaths due to COVID-19, comparing to 128 vaccine-attributable myocarditis/pericarditis cases, 110 hospitalizations, zero ICU admissions, and zero deaths. Uncertainties in the pandemic trajectory, effectiveness of vaccine against novel variants, and vaccine-attributable myocarditis/pericarditis rate are important limitations of our analysis. Also, the model does not evaluate potential long-term adverse effects due to either COVID-19 or vaccine-attributable myocarditis/pericarditis.

Evaluation of potential adverse events following COVID-19 mRNA vaccination among adults aged 65 years and older: Two self-controlled studies in the U.S

BACKGROUND

Our near-real-time safety monitoring of 16 adverse events (AEs) following COVID-19 mRNA vaccination identified potential elevation in risk for six AEs following primary series and monovalent booster dose administration. The crude association with AEs does not imply causality. Accordingly, we conducted robust evaluation of potential associations.

METHODS

We conducted two self-controlled case series studies of COVID-19 mRNA vaccines (BNT162b2 and mRNA-1273) in U.S. Medicare beneficiaries aged ≥ 65 years. Adjusted incidence rate ratio (IRRs) and 95 % confidence intervals (CIs) were estimated following primary series doses for acute myocardial infarction (AMI), pulmonary embolism (PE), immune thrombocytopenia (ITP), disseminated intravascular coagulation (DIC); and following monovalent booster doses for AMI, PE, ITP, Bell's Palsy (BP) and Myocarditis/Pericarditis (Myo/Peri).

RESULTS

The primary series study included 3,360,981 individuals who received 6,388,542 primary series doses; the booster study included 6,156,100 individuals with one monovalent booster dose. The AMI IRR following BNT162b2 primary series and booster was 1.04 (95 % CI: 0.91 to 1.18) and 1.06 (95 % CI: 1.003 to 1.12), respectively; for mRNA-1273 primary series and booster, 1.01 (95 % CI: 0.82 to 1.26) and 1.05 (95 % CI: 0.998 to 1.11), respectively. The hospital inpatient PE IRR following BNT162b2 primary series and booster was 1.19 (95 % CI: 1.03 to 1.38) and 0.86 (95 % CI: 0.78 to 0.95), respectively; for mRNA-1273 primary series and booster, 1.15 (95 % CI: 0.94 to 1.41) and 0.87 (95 % CI: 0.79 to 0.96), respectively. The studies' results do not support that exposure to COVID-19 mRNA vaccines elevate the risk of ITP, DIC, Myo/Peri, and BP.

CONCLUSION

We did not find an increased risk for AMI, ITP, DIC, BP, and Myo/Peri and there was not consistent evidence for PE after exposure to COVID-19 mRNA primary series or monovalent booster vaccines. These results support the favorable safety profile of COVID-19 mRNA vaccines administered in the U.S. elderly population.

Use of Immunization Information Systems in Ascertainment of COVID-19 Vaccinations for Claims-Based Vaccine Safety and Effectiveness Studies

Importance

Safety and effectiveness studies of COVID-19 vaccines are being conducted using clinical data, including administrative claims. However, claims data only partially capture administered COVID-19 vaccine doses for numerous reasons, such as vaccination at sites that do not generate claims for reimbursement.

Objective

To evaluate the extent to which Immunization Information Systems (IIS) data linked to claims data enhances claims-based COVID-19 vaccine capture for a commercially insured population and to estimate the magnitude of misclassification of vaccinated individuals as having unvaccinated status in the linked IIS and claims data.

Design, Setting, and Participants

This cohort study used claims data from a commercial health insurance database and obtained vaccination data from IIS repositories in 11 US states. Participants were individuals younger than 65 years who resided in 1 of 11 states of interest and who were insured in health plans from December 1, 2020, through December 31, 2021.

Main Outcomes and Measures

Estimated proportion of individuals with at least 1 dose of any COVID-19 vaccine and proportion of individuals with a completed vaccine series based on general population guidelines. Vaccination status estimates were calculated and compared using claims data alone and linked IIS and claims data. Remaining misclassification of vaccination status was assessed by comparing linked IIS and claims data estimates with estimates from external surveillance data sources (Centers for Disease Control and Prevention [CDC] and state Department of Health [DOH]) and capture-recapture analysis.

Results

This cohort study included 5 112 722 individuals (mean [SD] age, 33.5 [17.6] years; 2 618 098 females [51.2%]) from 11 states. Characteristics of those who received at least 1 vaccine dose and those who completed a vaccine series were similar to the overall study population. The proportion with at least 1 vaccine dose increased from 32.8% using claims data alone to 48.1% when the data were supplemented with IIS vaccination records. Vaccination estimates using linked IIS and claims data varied widely by state. The percentage of individuals who completed a vaccine series increased from 24.4% to 41.9% after the addition of IIS vaccine records and varied across states. The percentages of underrecording using linked IIS and claims data were 12.1% to 47.1% lower than those using CDC data, 9.1% to 46.9% lower than the state DOH, and 9.2% to 50.9% lower than capture-recapture analysis.

Conclusion and Relevance

Results of this study suggested that supplementing COVID-19 claims records with IIS vaccination records substantially increased the number of individuals who were identified as vaccinated, yet potential underrecording remained. Improvements in reporting vaccination data to IIS infrastructures could allow frequent updates of vaccination status for all individuals and all vaccines.

A Retrospective Review of Center for Biologics Evaluation and Research Advisory Committee Meetings in the Context of the FDA's Benefit-Risk Framework

The US FDA Center for Biologics Evaluation and Research (CBER) is responsible for the regulation of biologically derived products. FDA has established Advisory Committees (AC) as vehicles to seek external expert advice on scientific and technical matters related to the development and evaluation of products regulated by the agency. We aimed to identify and evaluate common topics discussed in CBER AC meetings during the regulatory decision-making process for biological products and medical devices. We analyzed the content of 119 CBER-led AC meetings between 2009 and 2021 listed on the FDA AC webpage. We reviewed publicly available meeting materials such as briefing documents, summaries, and transcripts. Using a structured review codebook based on FDA benefit-risk guidance, we identified important considerations within the benefit-risk dimensions discussed at the AC meetings: therapeutic context, benefit, risk and risk management, and benefit-risk trade-off, where evidence and uncertainty are critical parts of the FDA benefit-risk framework. Based on a detailed review of 24 topics discussed in 23 selected AC meetings conducted between 2016 and 2021, the two most frequently discussed considerations were "Uncertainty about assessment of the safety profile" and "Uncertainty about assessment of the benefit based on clinical trial data" (16/24 times each) as defined in our codebook. Most of the reviewed meetings discussed Investigational New Drug or Biologics License Applications of products. This review could help sponsors better plan and design studies by contextualizing how the benefit-risk dimensions were embedded in the AC discussions and the considerations that went into the final AC recommendations.

Surveillance of COVID-19 vaccine safety among elderly persons aged 65 years and older

BACKGROUND

Monitoring safety outcomes following COVID-19 vaccination is critical for understanding vaccine safety especially when used in key populations such as elderly persons age 65 years and older who can benefit greatly from vaccination. We present new findings from a nationally representative early warning system that may expand the safety knowledge base to further public trust and inform decision making on vaccine safety by government agencies, healthcare providers, interested stakeholders, and the public.

METHODS

We evaluated 14 outcomes of interest following COVID-19 vaccination using the US Centers for Medicare & Medicaid Services (CMS) data covering 30,712,101 elderly persons. The CMS data from December 11, 2020 through Jan 15, 2022 included 17,411,342 COVID-19 vaccinees who received a total of 34,639,937 doses. We conducted weekly sequential testing and generated rate ratios (RR) of observed outcome rates compared to historical (or expected) rates prior to COVID-19 vaccination.

FINDINGS

Four outcomes met the threshold for a statistical signal following BNT162b2 vaccination including pulmonary embolism (PE; RR = 1.54), acute myocardial infarction (AMI; RR = 1.42), disseminated intravascular coagulation (DIC; RR = 1.91), and immune thrombocytopenia (ITP; RR = 1.44). After further evaluation, only the RR for PE still met the statistical threshold for a signal; however, the RRs for AMI, DIC, and ITP no longer did. No statistical signals were identified following vaccination with either the mRNA-1273 or Ad26 COV2.S vaccines.

INTERPRETATION

This early warning system is the first to identify temporal associations for PE, AMI, DIC, and ITP following BNT162b2 vaccination in the elderly. Because an early warning system does not prove that the vaccines cause these outcomes, more robust epidemiologic studies with adjustment for confounding, including age and nursing home residency, are underway to further evaluate these signals. FDA strongly believes the potential benefits of COVID-19 vaccination outweigh the potential risks of COVID-19 infection.

A Risk Assessment Model for Transfusion Transmission of Dengue

Dengue virus (DENV) is a disease-causing agent normally transmitted from person to person through the bite of an infected mosquito. In addition to mosquito-borne cases of dengue, there are instances of transmission of dengue after receipt of blood products or donor organs or tissue. To improve blood safety, we developed a quantitative risk assessment model to estimate the dengue risk of transmission to blood transfusion recipients from preclinical and subclinical blood donors. We derived predictive coefficients from model simulations for predicting the risk outcomes such as monthly infectious blood units and transfusion-transmitted DENV cases based on the rate of reported clinical cases. The model was validated with a previous study where donor blood samples from the 2012 dengue transmission season in Rio de Janeiro, Brazil were tested for DENV RNA by a transcription-mediated amplification (TMA) assay. In that study about 69.4% donations were tested by the TMA assay and 78 samples were found positive, indicating that 112 DENV RNA-positive donations would have been detected if testing screening had been performed on all donations. Our model estimated a mean of 93 (2.5^th%ile -97.5^th%ile : 47 - 186) infected units among the donations, which was consistent with the reported numbers.

Regulatory considerations for study of infant protection through maternal immunization

Childhood Immunization is one of the critical strategies to decrease infant morbidity and mortality due to infectious diseases, but primary immunization schedules for infants in most countries start at 2 months of age. Childhood vaccines therefore begin providing adequate protection later in life, leaving infants vulnerable to infectious diseases and creating an immunity gap that results in higher morbidity and mortality among younger infants. Maternal immunization, the practice of vaccinating individuals during pregnancy, reduces the risk of infant infection primarily through the transfer of protective maternal antibodies to the fetus during late pregnancy. Although much progress has been made in public health policies to support maternal immunization research, inclusion of pregnant individuals and children in clinical trials remains challenging. This has resulted in paucity of evidence regarding safety and effectiveness of vaccines to support licensure of products intended for use during pregnancy and lactation to prevent disease in the infant. In addition, although safeguards for clinical research in pregnancy are supportive, experimental vaccines, e.g., Respiratory Syncytial Virus, are more complicated to study because data on safety, efficacy, and dosing are limited. This requires randomized controlled trials with safety monitoring for the mother, the fetus, and the infant with follow-up for at least 1 year or longer to assess long-term health outcomes that may be associated with peripartum vaccine exposure. The goal of this paper is to discuss the general regulatory considerations for clinical research to evaluate safety and effectiveness of vaccines administered during pregnancy to protect infants from disease. This could be useful to inform future vaccine trials. This discussion is not intended to provide agency guidance nor to articulate agency policy.

Benefit-risk assessment of COVID-19 vaccine, mRNA (Comirnaty) for age 16-29 years

Since authorization of the Pfizer-BioNTech COVID-19 Vaccine, mRNA (Comirnaty), real-world evidence has indicated the vaccines are effective in preventing COVID-19 cases and related hospitalizations and deaths. However, increased cases of myocarditis/pericarditis have been reported in the United States associated with vaccination, particularly in adolescents and young adults. FDA conducted a benefit-risk assessment to determine whether the benefits of vaccination outweigh the risks among various age (16–17, 18–24, 25–29) and sex (M/F) subgroups being considered for approved use of the vaccine. We conducted a simulation study with sensitivity analysis of the benefits and risks of the vaccine across possible pandemic scenarios. The model results show benefits outweigh the risks for all scenarios including the high-risk subgroup, males 16–17 years old. Our worst-case scenario used sex and age subgroup-specific incidences for COVID-19 cases (47–98 per million per day) and hospitalizations (1–4 per million per day) which are the US COVID-19 incidences as of July 10, 2021, vaccine efficacy of 70% against COVID-19 cases and 80% against hospitalization, and unlikely, pessimistic, non-zero vaccine-attributable myocarditis death rate. For males 16–17 years old, the model predicts prevented COVID cases, hospitalizations, ICUs, and deaths of 13577, 127, 41, and 1, respectively; while the predicted ranges for excess myocarditis/pericarditis cases, hospitalizations, and deaths attributable to the vaccine are [98–196], [98–196], and 0, respectively, for the worst-case scenario. Considering the different clinical implications of hospitalization due to COVID-19 infection versus vaccine-attributable myocarditis/pericarditis cases, we determine the benefits still outweigh the risks even for this high-risk subgroup. Our results demonstrate that the benefits of the vaccine outweigh its risks for all age and sex subgroups we analyze in this study. Uncertainties exist in this assessment as both benefits and risks of vaccination may change with the continuing evolution of the pandemic.

Risk of Guillain-Barré Syndrome Following Recombinant Zoster Vaccine in Medicare Beneficiaries

IMPORTANCE

Guillain-Barré syndrome can be reported after vaccination. This study assesses the risk of Guillain-Barré syndrome after administration of recombinant zoster vaccine (RZV or Shingrix), which is administered in 2 doses 2 to 6 months apart.

OBJECTIVE

Use Medicare claims data to evaluate risk of developing Guillain-Barré syndrome following vaccination with zoster vaccine.

DESIGN, SETTING, AND PARTICIPANTS

This case series cohort study included 849 397 RZV-vaccinated and 1 817 099 zoster vaccine live (ZVL or Zostavax)-vaccinated beneficiaries aged 65 years or older. Self-controlled analyses included events identified from 2 113 758 eligible RZV-vaccinated beneficiaries 65 years or older. We compared the relative risk of Guillain-Barré syndrome after RZV vs ZVL, followed by claims-based and medical record-based self-controlled case series analyses to assess risk of Guillain-Barré syndrome during a postvaccination risk window (days 1-42) compared with a control window (days 43-183). In self-controlled analyses, RZV vaccinees were observed from October 1, 2017, to February 29, 2020. Patients were identified in the inpatient, outpatient procedural (including emergency department), and office settings using Medicare administrative data.

EXPOSURES

Vaccination with RZV or ZVL vaccines.

MAIN OUTCOMES AND MEASURES

Guillain-Barré syndrome was identified in Medicare administrative claims data, and cases were assessed through medical record review using the Brighton Collaboration case definition.

RESULTS

Amongst those who received RZV vaccinees, the mean age was 74.8 years at first dose, and 58% were women, whereas among those who received the ZVL vaccine, the mean age was 74.3 years, and 60% were women. In the cohort analysis we detected an increase in risk of Guillain-Barré syndrome among RZV vaccinees compared with ZVL vaccinees (rate ratio [RR], 2.34; 95% CI, 1.01-5.41; P = .047). In the self-controlled analyses, we observed 24 and 20 cases during the risk and control period, respectively. Our claims-based analysis identified an increased risk in the risk window compared with the control window (RR, 2.84; 95% CI, 1.53-5.27; P = .001), with an attributable risk of 3 per million RZV doses (95% CI, 0.62-5.64). Our medical record-based analysis confirmed this increased risk (RR, 4.96; 95% CI, 1.43-17.27; P = .01).

CONCLUSIONS AND RELEVANCE

Findings of this case series cohort study indicate a slightly increased risk of Guillain-Barré syndrome during the 42 days following RZV vaccination in the Medicare population, with approximately 3 excess Guillain-Barré syndrome cases per million vaccinations. Clinicians and patients should be aware of this risk, while considering the benefit of decreasing the risk of herpes zoster and its complications through an efficacious vaccine, as risk-benefit balance remains in favor of vaccination.

Risk of Covid-19-Related Hospitalization and More Severe Outcomes in Medicare Beneficiaries Treated with Renin-Angiotensin-Aldosterone System Inhibitors for Hypertension

BACKGROUND

There are theoretical concerns that angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) could increase the risk of severe Covid-19.

OBJECTIVE

To determine if ACEIs and ARBs are associated with an increased risk of Covid-19 hospitalization overall, or hospitalization involving intensive care unit (ICU) admission, invasive mechanical ventilation, or death.

DESIGN

Observational case-control study.

PARTICIPANTS

Medicare beneficiaries aged ≥ 66 years with hypertension, treated with ACEIs, ARBs, calcium channel blockers (CCBs), or thiazide diuretics.

MAIN MEASURES

Adjusted odds ratios (OR) and 95% confidence intervals (CI) for the outcomes of Covid-19 hospitalization, or hospitalization involving ICU admission, invasive mechanical ventilation, or death.

RESULTS

A total of 35,300 cases of hospitalized Covid-19 were matched to 228,228 controls on calendar date and neighborhood of residence. The median age of cases was 79 years, 57.4% were female, and the median duration of hospitalization was 8 days (interquartile range 5-12). ACEIs and ARBs were associated with a slight reduction in Covid-19 hospitalization risk compared with treatment with other first-line antihypertensives (OR for ACEIs 0.95, 95% CI 0.92-0.98; OR for ARBs 0.94, 95% CI 0.90-0.97). Similar results were obtained for hospitalizations involving ICU admission, invasive mechanical ventilation, or death. There were no meaningful differences in risk for ACEIs compared with ARBs. In an analysis restricted to monotherapy with a first-line agent, CCBs were associated with a small increased risk of Covid-19 hospitalization compared with ACEIs (OR 1.09, 95% CI 1.04-1.14), ARBs (OR 1.10, 95% CI 1.05-1.15), or thiazide diuretics (OR 1.11, 95% CI 1.03-1.19).

CONCLUSIONS

ACEIs and ARBs were not associated with an increased risk of Covid-19 hospitalization or with hospitalization involving ICU admission, invasive mechanical ventilation, or death. The finding of a small increased risk of Covid-19 hospitalization with CCBs was unexpected and could be due to residual confounding.

Risk factors for COVID-19 deaths among elderly nursing home Medicare beneficiaries in the pre-vaccine period

BACKGROUND

Evaluate pre-vaccine pandemic period COVID-19 death risk factors among nursing home (NH) residents.

METHODS

Retrospective cohort study covering Medicare fee-for-service beneficiaries ages ≥65 residing in U.S. NHs. We estimated adjusted hazard ratios (HRs) using multivariate Cox proportional hazards regressions.

RESULTS

Among 608,251 elderly NH residents, 57,398 (9.4%) died of COVID-related illness April 1 to December 22, 2020. About 46.9% (26,893) of these COVID-19 deaths occurred without prior COVID-19 hospitalizations. We observed a consistently increasing age trend for COVID-19 deaths. Racial/ethnic minorities generally shared a similarly high risk of NH COVID-19 deaths with Whites. NH facility characteristics including for-profit ownership and low health inspection ratings were associated with higher death risk. Resident characteristics, including male (HR 1.69), end-stage renal disease (HR 1.42), cognitive impairment (HR 1.34), and immunocompromised status (HR 1.20) were important death risk factors. Other individual-level characteristics were less predictive of death than they were in community-dwelling population.

CONCLUSIONS

Low NH health inspection ratings and private ownership contributed to COVID-19 death risks. Nearly half of NH COVID-19 deaths occurred without prior COVID-19 hospitalization and older residents were less likely to get hospitalized with COVID-19. No substantial differences were observed by race/ethnicity and socioeconomic status for NH COVID-19 deaths.

Comparison of hemagglutination inhibition and hemagglutinin pseudovirus neutralization titres in relation to protection against influenza in a mouse model

The hemagglutination inhibition (HI) test has long been used as a standard measure of antibody response for inactivated influenza vaccines. However, the HI test has limitations, such as insensitivity when using some H3N2 virus strains and failure to detect neutralizing antibodies that target regions distant from the receptor binding site. We therefore examined a hemagglutinin pseudovirus neutralization (PVN) test as a possible supplement or alternative to the HI test. We evaluated the association of HI or PVN titres with protection against influenza infection in mice based on morbidity (where the illness was defined as 25% body weight loss). We assessed this relationship using dose-response models incorporating HI or PVN titres as a variable. The morbidity was correlated with the pre-exposure titres, and such a correlation was well described by a modified dose-response model. The mathematical modelling suggests that PVN titres consistently show a stronger association with in vivo protection as compared to HI titres in mice. Given our findings, the PVN test warrants further investigation as a tool for evaluating antibody responses to influenza vaccines containing hemagglutinin. The resulting models may also be useful for analyzing human clinical data to identify potentially protective antibody titres against influenza illness.

A Quantitative Evaluation of COVID-19 Epidemiological Models

Quantifying how accurate epidemiological models of COVID-19 forecast the number of future cases and deaths can help frame how to incorporate mathematical models to inform public health decisions. Here we analyze and score the predictive ability of publicly available COVID-19 epidemiological models on the COVID-19 Forecast Hub. Our score uses the posted forecast cumulative distributions to compute the log-likelihood for held-out COVID-19 positive cases and deaths. Scores are updated continuously as new data become available, and model performance is tracked over time. We use model scores to construct ensemble models based on past performance. Our publicly available quantitative framework may aid in improving modeling frameworks, and assist policy makers in selecting modeling paradigms to balance the delicate trade-offs between the economy and public health.

Babesiosis Occurrence Among United States Medicare Beneficiaries, Ages 65 and Older, During 2006-2017: Overall and by State and County of Residence

Background

Human babesiosis is a mild-to-severe parasitic infection that poses health concerns especially in older and other at-risk populations. The study objective was to assess babesiosis occurrence among US Medicare beneficiaries, ages 65 and older, during 2006-2017.

Methods

Our retrospective claims-based study used Medicare databases. Babesiosis cases were identified using recorded diagnosis codes. The study estimated rates (per 100 000 beneficiary-years) overall, by year, diagnosis month, demographics, and state and county of residence.

Results

Nationwide, 19 469 beneficiaries had babesiosis recorded, at a rate of 6 per 100 000 person-years, ranging from 4 in 2006 to 9 in 2017 (P < .05). The highest babesiosis rates by state were in the following: Massachusetts (62), Rhode Island (61), Connecticut (51), New York (30), and New Jersey (19). The highest rates by county were in the following: Nantucket, Massachusetts (1089); Dukes, Massachusetts (236); Barnstable, Massachusetts (213); and Dutchess, New York (205). Increasing rates, from 2006 through 2017 (P < .05), were identified in multiple states, including states previously considered nonendemic. New Hampshire, Maine, Vermont, Pennsylvania, and Delaware saw rates increase by several times.

Conclusions

Our 12-year study shows substantially increasing babesiosis diagnosis trends, with highest rates in well established endemic states. It also suggests expansion of babesiosis infections in other states and highlights the utility of real-world evidence.

Guillain-Barré Syndrome After High-Dose Influenza Vaccine Administration in the United States, 2018-2019 Season

BACKGROUND

The Vaccine Safety Datalink (VSD) identified a statistical signal for an increased risk of Guillain-Barré syndrome (GBS) in days 1-42 after 2018-2019 high-dose influenza vaccine (IIV3-HD) administration. We evaluated the signal using Medicare.

METHODS

We conducted early- and end-of-season claims-based self-controlled risk interval analyses among Medicare beneficiaries ages ≥65 years, using days 8-21 and 1-42 postvaccination as risk windows and days 43-84 as control window. The VSD conducted chart-confirmed analyses.

RESULTS

Among 7 453 690 IIV3-HD vaccinations, we did not detect a statistically significant increased GBS risk for either the 8- to 21-day (odds ratio [OR], 1.85; 95% confidence interval [CI], 0.99-3.44) or 1- to 42-day (OR, 1.31; 95% CI, 0.78-2.18) risk windows. The findings from the end-of-season analyses were fully consistent with the early-season analyses for both the 8- to 21-day (OR, 1.64; 95% CI, 0.92-2.91) and 1- to 42-day (OR, 1.12; 95% CI, 0.70-1.79) risk windows. The VSD's chart-confirmed analysis, involving 646 996 IIV3-HD vaccinations, with 1 case each in the risk and control windows, yielded a relative risk of 1.00 (95% CI, 0.06-15.99).

CONCLUSIONS

The Medicare analyses did not exclude an association between IIV3-HD and GBS, but it determined that, if such a risk existed, it was similar in magnitude to prior seasons. Chart-confirmed VSD results did not confirm an increased risk of GBS.

Effect of Age on Relative Effectiveness of High-Dose Versus Standard-Dose Influenza Vaccines Among US Medicare Beneficiaries Aged ≥65 Years

BACKGROUND

Studies have found that the high-dose influenza vaccine has a higher relative vaccine effectiveness (RVE) versus standard-dose vaccines in some seasons. We evaluated the effect of age on the RVE of high-dose versus standard-dose influenza vaccines among Medicare beneficiaries.

METHODS

A 6-season retrospective cohort study from 2012 to 2018 among Medicare beneficiaries aged ≥65 years was performed. Poisson regression was used to evaluate the effect of age on the RVE of high-dose versus standard-dose influenza vaccines in preventing influenza-related hospitalizations.

RESULTS

The study included >19 million vaccinated beneficiaries in a community pharmacy setting. The Poisson models indicated a slightly increasing trend in RVE with age in all seasons. The high-dose vaccine was more effective than standard-dose vaccines in preventing influenza-related hospital encounters (ie, influenza-related inpatient stays and emergency department visits) in the 2012-2013 (RVE, 23.1%; 95% confidence interval [CI], 17.6%-28.3%), 2013-2014 (RVE, 15.3%; 95% CI, 7.8%-22.3%), 2014-2015 (RVE, 8.9%; 95% CI, 5.6%-12.1%), and 2016-2017 (RVE, 12.6%; 95% CI, 6.3%-18.4%) seasons and was at least as effective in all other seasons. We also found that the high-dose vaccine was consistently more effective than standard-dose vaccines across all seasons for people aged ≥85 years. Similar trends were observed for influenza-related inpatient stays.

CONCLUSIONS

The RVE of high-dose versus standard-dose influenza vaccines increases with age.

Assessment of risk of variant creutzfeldt-Jakob disease (vCJD) from use of bovine heparin

PURPOSE

In the late1990s, reacting to the outbreak of bovine spongiform encephalopathy (BSE) in the United Kingdom that caused a new variant of Creutzfeldt-Jakob disease (vCJD) in humans, manufacturers withdrew bovine heparin from the market in the United States. There have been growing concerns about the adequate supply and safety of porcine heparin. Since the BSE epidemic has been declining markedly, the US Food and Drug Administration reevaluates the vCJD risk via use of bovine heparin.

METHODS

We developed a computational model to estimate the vCJD risk to patients receiving bovine heparin injections. The model incorporated information including BSE prevalence, infectivity levels in the intestines, manufacturing batch size, yield of heparin, reduction in infectivity by manufacturing process, and the dose-response relationship.

RESULTS

The model estimates a median risk of vCJD infection from a single intravenous dose (10 000 USP units) of heparin made from US-sourced bovine intestines to be 6.9 × 10^-9 (2.5-97.fifth percentile: 1.5 × 10^-9 -4.3 × 10^-8 ), a risk of 1 in 145 million, and 4.6 × 10^-8 (2.5-97.fifth percentile: 1.1 × 10^-8 -2.6 × 10^-7 ), a risk of 1 in 22 million for Canada-sourced products. The model estimates a median risk of 1.4 × 10^-7 (2.5-97.fifth percentile: 2.9 × 10^-8 -9.3 × 10^-7 ) and 9.6 × 10^-7 (2.5-97.fifth percentile: 2.1 × 10^-7 -5.6 × 10^-6 ) for a typical treatment for venous thromboembolism (infusion of 2-4 doses daily per week) using US-sourced and Canada-sourced bovine heparin, respectively.

CONCLUSIONS

The model estimates the vCJD risk from use of heparin when appropriately manufactured from US or Canadian cattle is likely small. The model and conclusions should not be applied to other medicinal products manufactured using bovine-derived materials.

Comparative pharmacokinetic and biodistribution study of two distinct squalene-containing oil-in-water emulsion adjuvants in H5N1 influenza vaccines

BACKGROUND

In recent years, there has been great interest from academia, industry and government scientists for an increased understanding of the mode of action of vaccine adjuvants to characterize the safety and efficacy of vaccines. In this context, pharmacokinetic (PK) and biodistribution studies are useful for quantifying the concentration of vaccine adjuvants in mechanistically or toxicologically relevant target tissues.

METHODS

In this study, we conducted a comparative analysis of the PK and biodistribution profile of radiolabeled squalene for up to 336 h (14 days) after intramuscular injection of mice with adjuvanted H5N1 influenza vaccines. The evaluated adjuvants included an experimental-grade squalene-in-water (SQ/W) emulsion (AddaVax®) and an adjuvant system (AS03®) that contained squalene and α-tocopherol in the oil phase of the emulsion.

RESULTS

The half-life of the initial exponential decay from quadriceps muscle was 1.5 h for AS03 versus 12.9 h for AddaVax. At early time points (1-6 h), there was about a 10-fold higher concentration of labeled squalene in draining lymph nodes following AS03 injection compared to AddaVax. The area-under-concentration curve up to 336 h (AUC_0-336hr) and peak concentration of squalene in spleen (immune organ) was about 1.7-fold higher following injection of AS03 than AddaVax. The peak systemic tissue concentration of squalene from the two adjuvants, with or without antigen, remained below 1% of injected dose for toxicologically relevant target tissues, such as spinal cord, brain, and kidney. The pharmacokinetics of AS03 was unaffected by the presence of H5N1 antigen.

CONCLUSIONS

This study demonstrates a rapid decline of AS03 from the quadriceps muscles of mice as compared to conventional SQ/W emulsion adjuvant, with an increased transfer to mechanistically relevant tissues such as local lymph nodes. Systemic tissue exposure to potential toxicological target tissues was very low.

A simulation study of the statistical power and signaling characteristics of an early season sequential test for influenza vaccine safety

PURPOSE

The US Food and Drug Administration monitors the risk of Guillain-Barré syndrome (GBS) following influenza vaccination using several data sources including Medicare. In the 2017 to 2018 season, we transitioned our near real-time surveillance in Medicare to more effectively detect large GBS risk increases early in the season while avoiding false positives.

METHODS

We conducted a simulation study examining the ability of the updating sequential probability ratio test (USPRT) to detect substantially elevated GBS risk in the 8- to 21-day postvaccination versus 5× to 30× the historical rate. We varied the first testing week (weeks 5-8) and the null rate (1×-3×) and evaluated power. We estimated signal probability and the risk ratio (RR) after signaling when high-risk seasons were rare.

RESULTS

Applying fixed alternatives, we found >80% power to detect a risk 30× the historical rate in week 5 for the 1× null and in week 6 for the 1.5× to 3× nulls. Nearly all testing schedules had >80% power for a 5× risk by week 11. To test the robustness of USPRT, we further simulated seasons where 1% were true high-risk seasons. Using a 1× null led to 10% of seasons signaling by week 11 (median RR approximately 1.4), which decreased to approximately 1% with the ≥2.5× null (median RR approximately 16.0).

CONCLUSIONS

On the basis of the results from this simulation and subsequent consultations with experts and stakeholders, we specified USPRT to test continuously from weeks 7 to 11 using the null hypothesis that the observed GBS rate was 2.5× the historical rate. This helped improve the ability of USPRT to provide early detection of GBS risk following influenza vaccination as part of a multilayered system of surveillance.

Surveillance for Guillain-Barré syndrome after influenza vaccination among U.S. Medicare beneficiaries during the 2017-2018 season

BACKGROUND

The U.S. Food and Drug Administration and the Centers for Medicare & Medicaid Services have been actively monitoring the risk of Guillain-Barré syndrome (GBS) following influenza vaccination among Fee-for-Service (FFS) Medicare beneficiaries every season since 2008. We present our evaluation of the GBS risk following influenza vaccinations during the 2017-2018 season.

METHODS

We implemented a multilayered approach to active safety surveillance that included near real-time surveillance early in the season, comparing GBS rates post-vaccination during the 2017-2018 season with rates from five prior seasons using the Updating Sequential Probability Ratio Test (USPRT), and end-of-season self-controlled risk interval (SCRI) analyses.

RESULTS

We identified approximately 16 million influenza vaccinations. The near real-time surveillance did not signal for a potential 2.5-fold increased GBS risk either in days 8-21 or 1-42 post-influenza vaccination. In the SCRI analyses, we did not detect statistically significant increased GBS risks among influenza-vaccinated Medicare beneficiaries ≥65 years for either the 8-21 or 1-42-day risk windows for all seasonal vaccines combined, high-dose vaccine, or standard-dose vaccines; we did detect an increased GBS risk in days 8-21 post-vaccination for individuals vaccinated with the adjuvanted vaccine (OR: 3.75; 95% CI: 1.01, 13.96), although this finding was not statistically significant after multiplicity adjustment (p = 0.146).

CONCLUSIONS

Our multilayered surveillance approach-which allows for early detection of elevated GBS risk and provides reliable end-of-season SCRI estimates of effect size-did not identify an increased GBS risk following 2017-2018 influenza vaccinations. The slightly increased GBS risk with the adjuvanted vaccine, which was not statistically significant following multiplicity adjustment, is consistent with the package inserts of all U.S.-licensed influenza vaccines, which warn of a potential low increased GBS risk. The benefits of influenza vaccines in preventing morbidity and mortality heavily outweigh this potential risk.

Predictive model for Zika virus RNA minipool nucleic acid testing in outbreak scenarios

BACKGROUND

Zika virus (ZIKV), a mosquito-borne flavivirus, causes asymptomatic infections in blood donors and can be transmitted by transfusion. During the 2016 US outbreak, universal individual-donation nucleic acid testing (ID-NAT) was used to screen the blood supply for ZIKV. Testing pooled samples from multiple donations with minipool (MP)-NAT is less sensitive than ID-NAT, which raised questions about its utility in ZIKV outbreaks.

STUDY DESIGN AND METHODS

A mathematical model and computer simulation determined the risk of missing ID-NAT-reactive and immunoglobulin (Ig) M-negative donations in a ZIKV outbreak if MP-NAT is used initially instead of ID-NAT. The model calculated the time required for ZIKV RNA to replicate to a concentration detectable by testing donations individually or in pools of 6 (MP6) or 16 (MP16). A computer simulation then randomly selected infection times to determine the probability of detection by the candidate tests.

RESULTS

The probability of detecting the first ID-NAT-reactive unit in an outbreak is 92% (2.5th-97.5th percentile, 79%-99%) by MP6 and 85% (2.5th-97.5th percentile, 67%-99%) by MP16. When one donation is detected by MP-NAT, the model predicts that the chance of having missed one or more ID-NAT-reactive donations is 8% to 15%. The probability of missing a unit by MP-NAT is constant over the course of the outbreak (8% by MP6, 15% by MP16).

CONCLUSION

The model predicts that the probability that a candidate MP-NAT will detect the first ID-NAT-reactive unit in a ZIKV outbreak is 85% to 92% and remains constant over time.

Patterns of seasonal influenza activity in U.S. core-based statistical areas, described using prescriptions of oseltamivir in Medicare claims data

Using Medicare claims data on prescriptions of oseltamivir dispensed to people 65 years old and older, we present a descriptive analysis of patterns of influenza activity in the United States for 579 core-based statistical areas (CBSAs) from the 2010–2011 through the 2015–2016 influenza seasons. During this time, 1,010,819 beneficiaries received a prescription of oseltamivir, ranging from 45,888 in 2011–2012 to 380,745 in 2014–2015. For each season, the peak weekly number of prescriptions correlated with the total number of prescriptions (Pearson’s r ≥ 0.88). The variance in peak timing decreased with increasing severity (p < 0.0001). Among these 579 CBSAs, neither peak timing, nor relative timing, nor severity of influenza seasons showed evidence of spatial autocorrelation (0.02 ≤ Moran’s I ≤ 0.23). After aggregating data to the state level, agreement between the seasonal severity at the CBSA level and the state level was fair (median Cohen’s weighted κ = 0.32, interquartile range = 0.26–0.39). Based on seasonal severity, relative timing, and geographic place, we used hierarchical agglomerative clustering to join CBSAs into influenza zones for each season. Seasonal maps of influenza zones showed no obvious patterns that might assist in predicting influenza zones for future seasons. Because of the large number of prescriptions, these data may be especially useful for characterizing influenza activity and geographic distribution during low severity seasons, when other data sources measuring influenza activity are likely to be sparse.

Evaluating oseltamivir prescriptions in Centers for Medicare and Medicaid Services medical claims records as an indicator of seasonal influenza in the United States

Background

Over 34 million residents of the United States aged 65 years and older are also Medicare prescription drug beneficiaries. Medical claims records for this age group potentially provide a wealth of data for better understanding influenza epidemiology.

Objective

The purpose of this study was to evaluate data on oseltamivir dispensing extracted from medical claims records as an indicator of influenza activity in the United States for the 2010‐11 through 2014‐15 influenza seasons.

Methods

We used Centers for Medicare and Medicaid Services (CMS) medical claims data to evaluate the weekly number of therapeutic oseltamivir prescriptions dispensed following a rapid influenza diagnostic test among beneficiaries 65 years old and older as an indicator of influenza timing and intensity. We compared the temporal changes in this indicator to changes in the proportion of influenza‐like illnesses among outpatient visits in the US Outpatient Influenza‐like Illness Surveillance Network (ILINet) by administrative regions defined by the US Department of Health and Human Services. Using the moving epidemic method, we determined intensity thresholds and categorized the severity of seasons for both CMS and ILINet data.

Results

Centers for Medicare and Medicaid Services oseltamivir data and ILINet data were strongly correlated by administrative region (median Spearman's ρ = 0.78; interquartile range = 0.73‐0.80). CMS oseltamivir data and ILINet data substantially agreed (Cohen's weighted κ = 0.62) as to the seasonal severity across administrative regions.

Conclusions

Our results support the use of oseltamivir dispensing in medical claims data as an indicator of US influenza activity.

Detection of human immunodeficiency virus, hepatitis C virus, and hepatitis B virus in postmortem blood specimens using infectious disease assays licensed for cadaveric donor screening

BACKGROUND

Evaluation of assay performance on postmortem blood specimens (obtained after cessation of the heartbeat) presents unique scientific and regulatory challenges. In the United States, assay performance is evaluated in part by spiking postmortem specimens.

METHODS

Fifty-four specimens obtained from decedents known to be infected with human immunodeficiency virus (HIV), hepatitis C virus (HCV), or hepatitis B virus (HBV), including some coinfections, were tested for each virus using Food and Drug Administration (FDA)-licensed donor screening tests for nucleic acid, antibody, and antigen.

RESULTS

For each disease, >95% of subjects who were reported to have an infection at the time of death had a positive test result on at least one of the donor screening assays for that infection.

CONCLUSION

Licensed donor screening tests were positive on postmortem specimens obtained within 24 hours of death from individuals dying with HIV, HCV, and/or HBV, and were able to detect presence of the virus. The use of multiple tests (including antibody and direct viral detection methods) is necessary to adequately evaluate donors.

Occurrence of acute renal failure on the same day as immune globulin product administrations during 2008 to 2014

BACKGROUND

Acute renal failure (ARF) is a rare serious adverse event after immune globulin (IG) use. Our large claims-based study evaluated occurrence of same-day ARF after administration of different IGs and ascertained potential risk factors, during the 2008 to 2014 study period.

STUDY DESIGN AND METHODS

A retrospective cohort study was conducted using a large commercial administrative database. The cohort included individuals exposed to IG products as identified by procedure codes. ARF was ascertained using ICD-9-CM diagnoses. Unadjusted same-day ARF rates (per 1000 persons exposed) were estimated overall and by age, sex, and IG products. Regression analyses were conducted to control for confounding and assess potential risk factors.

RESULTS

Of 20,440 persons exposed, 163 (7.97 per 1000) had a recorded same-day ARF. The unadjusted nonzero same-day ARF rates (per 1000) ranged from 1.92 (95% confidence interval [CI], 0.05-10.69) for Hizentra to 16.97 (95% CI, 11.36-24.37) for Privigen and differed by sex. In multivariate analyses, compared to Gammagard Liquid, no significantly elevated ARF risks were identified with any IGs. A significantly lower odds ratio was identified with Gamunex, 0.53 (95% CI, 0.30-0.93). Age 45 and over, prior renal impairment, hypertension, and other factors were associated with increased risk of same-day ARF.

CONCLUSION

The study showed variation in the risk of IG-related ARF by age, sex, and IG products. The study results suggest the importance of recipient factors, such as older age and underlying health conditions. Variations in ARF occurrence may also be explained by product dosage, administration route and rate, and manufacturing processes, which warrant further evaluation.

Advancing the science of patient input throughout the regulatory decision-making process

The US Food and Drug Administration (FDA) understands the value of patient input in the regulatory decision-making process and has worked to enhance meaningful engagement. In recent years, there has been an increased scientific demand for more systematic and quantitative approaches to incorporate patient input throughout the medical product lifecycle, including to inform regulatory benefit-risk assessments. The use of patient preference information (PPI), elicited using established scientific methods, is a promising strategy for accomplishing this. Although much of the science behind PPI is not new, its application in a regulatory setting will require adapting and advancing the science of identifying, collecting, and evaluating patient input for informing regulatory decision making. Patient input and empowerment are foundational to a learning healthcare system. A learning healthcare system paradigm can also help us better understand and continuously improve the incorporation of the patient perspective in regulatory decision making. In this article, we highlight the Food and Drug Administration's Center for Biologics Evaluation and Research experience and current initiatives on advancing the science of patient input in a regulatory setting, in particular, PPI. We provide a use case that explores how the principles and benefits of PPI applied in shared clinical decision making can be realized and leveraged to enhance regulatory evaluation of innovative therapies. To further advance the application of the science of patient input in our regulatory framework, we compiled a list of example resources that support stakeholders in designing and conducting PPI studies. More collaborative research among stakeholders is needed to establish best practice approaches, ensure scientific validity, and continuously learn and improve the systematic incorporation of scientific patient input throughout the regulatory decision-making process.

Predicting dose sparing benefit and bleeding risk of pharmacokinetic-based personalized prophylactic dosing of factor VIII products

BACKGROUND

Previously published factor VIII (FVIII) pharmacokinetic (PK)-based dosing approaches employ fixed infusion interval with a wide dose range that may lead to increased risk of bleeding, excessive doses or decreased health-related quality of life.

AIM

The objectives of the study includes (i) personalizing infusion interval in lieu of fixed infusion, (ii) constraining dose within the range of 10-50 IU/kg and (iii) characterizing bleeding risk of PK-based dosing in comparison with empiric standard doses.

METHODS

Patient demographics and PK parameters for conventional FVIII products were obtained from published literatures. Subject-specific PK parameters were derived from FVIII activities vs time data generated through simulation.

RESULTS

Our data indicated approximately 4%, 38%, 37% and 20% of the subjects can be dosed with infusion interval of every 24, 48, 72 and 96 hours, respectively, for maintaining a target 1 IU/dL FVIII level within the dose range of 10-50 IU/kg. Maintaining an alternative trough value of 3 or 5 IU/dL requires more frequent infusion. The predicted median probability of bleeding risk per year was 35.7% (range, 11%-49%) for PK-based dosing maintaining 1 IU/dL. Predicted median bleeding risk was 37.9% (0%-74%), 32.8% (0%-72%) and 26.7% (0%-70%) for standard dosing of 20, 30 and 50 IU/kg, respectively. PK-based dosing resulted in a dose sparing benefit compared to standard dose of 30 or 50 IU/kg three times per week.

CONCLUSION

The results of the study demonstrate the feasibility of individualizing infusion interval, restricting FVIII dose, trough and peak concentration within an acceptable range.

Comparative Effectiveness of High-Dose Versus Standard-Dose Influenza Vaccines Among US Medicare Beneficiaries in Preventing Postinfluenza Deaths During 2012-2013 and 2013-2014

Background

Recipients of high-dose vs standard-dose influenza vaccines have fewer influenza illnesses. We evaluated the comparative effectiveness of high-dose vaccine in preventing postinfluenza deaths during 2012-2013 and 2013-2014, when influenza viruses and vaccines were similar.

Methods

We identified Medicare beneficiaries aged ≥65 years who received high-dose or standard-dose vaccines in community-located pharmacies offering both vaccines. The primary outcome was death in the 30 days following an inpatient or emergency department encounter listing an influenza International of Classification of Diseases, Ninth Revision, Clinical Modification code. Effectiveness was estimated by using multivariate Poisson regression models; effectiveness was allowed to vary by season.

Results

We studied 1039645 recipients of high-dose and 1683264 recipients of standard-dose vaccines during 2012-2013, and 1508176 high-dose and 1877327 standard-dose recipients during 2013-2014. Vaccinees were well-balanced for medical conditions and indicators of frail health. Rates of postinfluenza death were 0.028 and 0.038/10000 person-weeks in high-dose and standard-dose recipients, respectively. Comparative effectiveness was 24.0% (95% confidence interval [CI], .6%-42%); there was evidence of variation by season (P = .12). In 2012-2013, high-dose was 36.4% (95% CI, 9.0%-56%) more effective in reducing mortality; in 2013-2014, it was 2.5% (95% CI, -47% to 35%).

Conclusions

High-dose vaccine was significantly more effective in preventing postinfluenza deaths in 2012-2013, when A(H3N2) circulation was common, but not in 2013-2014.

Modeling the potential impact on the US blood supply of transfusing critically ill patients with fresher stored red blood cells

Background

Although some studies have suggested that transfusion recipients may have better medical outcomes if transfused with red blood cell units stored for a short time, the overall body of evidence shows mixed results. It is important to understand how using fresher stored red blood cell units for certain patient groups may affect blood availability.

Methods

Based on the Stock-and-Flow simulation model of the US blood supply developed by Simonetti et al. 2014, we evaluated a newly implemented allocation method of preferentially transfusing fresher stored red blood cell units to a subset of high-risk group of critically ill patients and its potential impact on supply.

Results

Simulation results showed that, depending on the scenario, the US blood total supply might be reduced between 2-42%, when compared to the standard of care in transfusion medicine practice. Among our simulated scenarios, we observed that the number of expired red blood cell units modulated the supply levels. The age threshold of the required red blood cell units was inversely correlated with both the supply levels and the number of transfused units that failed to meet that age threshold.

Conclusion

To our knowledge, this study represents the first attempt to develop a comprehensive framework to evaluate the impact of preferentially transfusing fresher stored red blood cells to the higher-risk critically ill patients on supply. Model results show the difficulties to identify an optimal scenario.

Pharmacokinetics and biodistribution of squalene-containing emulsion adjuvant following intramuscular injection of H5N1 influenza vaccine in mice

Squalene is a component of oil-in-water emulsion adjuvants developed for potential use in some influenza vaccines. The biodistribution of the squalene-containing emulsion adjuvant (AddaVax™) alone and as part of complete H5N1 vaccine was quantified in mechanistically and toxicologically relevant target tissues up to 336 h (14 days) following injection into quadriceps muscle. At 1 h, about 55% of the intramuscularly injected dose of squalene was detected in the local quadriceps muscles and this decreased to 26% at 48 h. Twenty-four hours after the injection, approximately 5%, 1%, and 0.6% of the injected dose was detected in inguinal fat, draining lymph nodes, and sciatic nerve, respectively. The peak concentration for kidney, brain, spinal cord, bone marrow, and spleen was each less than 1% of the injected dose, and H5N1 antigen did not significantly alter the biodistribution of squalene to these tissues. The area-under-blood-concentration curve (AUC) and peak blood concentration (Cmax) of squalene were slightly higher (20-25%) in the presence of H5N1 antigen. A population pharmacokinetic model-based statistical analysis identified body weight and H5N1 antigen as covariates influencing the clearance of squalene. The results contribute to the body of knowledge informing benefit-risk analyses of squalene-containing emulsion vaccine adjuvants.

Quantitative Bias Analysis in Regulatory Settings

Nonrandomized studies are essential in the postmarket activities of the US Food and Drug Administration, which, however, must often act on the basis of imperfect data. Systematic errors can lead to inaccurate inferences, so it is critical to develop analytic methods that quantify uncertainty and bias and ensure that these methods are implemented when needed. "Quantitative bias analysis" is an overarching term for methods that estimate quantitatively the direction, magnitude, and uncertainty associated with systematic errors influencing measures of associations. The Food and Drug Administration sponsored a collaborative project to develop tools to better quantify the uncertainties associated with postmarket surveillance studies used in regulatory decision making. We have described the rationale, progress, and future directions of this project.

Clotting factor product administration and same-day occurrence of thrombotic events, as recorded in a large healthcare database during 2008-2013

BACKGROUND

Thrombotic events (TEs) are serious adverse events that can occur following administration of clotting factors (CFs).

OBJECTIVES

To evaluate occurrence of same-day TEs for different CF products and potential risk factors.

METHODS

A retrospective cohort study of individuals exposed to CF products during 2008-2013 was conducted using a large commercial insurance database. CF products were identified by procedure codes, and TEs were ascertained via diagnosis codes. Crude same-day TE rates (per 1000 persons exposed) were estimated overall and by congenital factor deficiency (CFD) status, CF products, age and gender. Multivariable logistic regression analyses were used to control for confounding. Laboratory analysis was used to compare the procoagulant activities of FIX products.

RESULTS

Of 3801 individuals exposed to CFs, 117 (30.8 per 1000) had same-day TEs recorded. The crude same-day TE rate was higher for CF users without CFD, 70.2 (102 of 1452), as compared with those with CFD, 6.4 (15 of 2349) (RR, 11.0; 95% CI, 6.4-18.9). For individuals without CFD, a significantly increased same-day TE risk was identified for factor IX complex (OR, 6.92; 95% CI, 3.11-15.40), factor VIIa (OR, 9.42; 95% CI, 4.99-17.78) and other products when compared with fibrin sealant. An increased risk of a TE was found with older age (≥ 45 years), history of TEs and underlying health conditions. The laboratory identified elevated procoagulant activity in Profilnine(®) and Benefix(®) .

CONCLUSIONS

The study shows an increased same-day TE risk for CF users without CFD and suggests substantial off-label CF use. The study findings also show elevated same-day TE rates for different CF products and suggest the importance of product properties and patient factors.

Overall conceptual framework for studying the genetics of autoimmune diseases following vaccination: a regulatory perspective

The US Vaccine Adverse Event Reporting System contains case reports of autoimmune diseases (ADs) occurring following vaccinations. ADs are rare and occur in unvaccinated people, making the potential association between vaccines and ADs challenging to evaluate. Developing mechanistic pathways that link genes, immune mediators, vaccine components and ADs would be helpful for hypothesis generation, enhancing theories of biologic plausibility and grouping rare autoimmune adverse events to increase the ability to detect and evaluate safety signals. Here, we propose a conceptual framework for investigating the genetics of ADs as safety signals following vaccination, potentially contributing to the identification of relevant biomarkers. We also discuss a study design that incorporates genetic information into postmarket clinical evaluation of autoimmune adverse events following vaccination.