National immunisation campaigns with oral polio vaccine may reduce all-cause mortality: Analysis of 2004-2019 demographic surveillance data in rural Bangladesh

Contradictory mortality results in early 2-dose measles vaccine trials: interactions with oral polio vaccine may explain differences

OBJECTIVES

Between 2003 and 2019, three trials (randomised controlled trials [RCTs]) in Guinea-Bissau randomised infants to an early 2-dose measles vaccine (MV) schedule at 4 and 9 months vs standard MV at 9 months. The RCTs produced contradictory mortality results; the effect being beneficial in the 2-dose group in the first but tending to have higher mortality in the last two RCTs. We hypothesised that increased frequency of campaigns with oral polio vaccine (C-OPV) explained the pattern.

METHODS

We performed per-protocol analysis of individual-level survival data from the three RCTs in Cox proportional hazards models yielding hazard ratios (HR) for the 2-dose vs the 1-dose MV group. We examined whether timing of C-OPVs and early administration of OPV0 (birth to day 14) affected the HRs for 2-dose/1-dose MV.

RESULTS

The combined HR(2-dose/1-dose) was 0.79 (95% confidence interval: 0.62-1.00) for children receiving no C-OPV-before-enrolment, but 1.39 (0.97-1.99) for those receiving C-OPV-before-enrolment (homogeneity, P = 0.01). C-OPV-before-enrolment had a beneficial effect in the 1-dose group but tended to have a negative effect in the 2-dose group, especially in females. These effects were amplified further by early administration of OPV0.

CONCLUSION

In the absence of C-OPVs, an early 2-dose MV strategy had beneficial effects on mortality, but frequent C-OPVs may have benefitted the 1-dose group more than the 2-dose MV group, leading to varying results depending on the intensity of C-OPVs.

Effect of a campaign with oral polio vaccine on general health: A cluster-randomised trial in rural Guinea-Bissau

OBJECTIVES

To investigate in a cluster-randomised trial whether a campaign with oral polio vaccine (C-OPV) reduced mortality and morbidity.

METHODS

We randomised 222 village clusters under demographic surveillance to an intervention (health check and C-OPV) or control group (health check only). Children aged 0-8 months were eligible. In Cox proportional hazards models with age as the underlying timescale, we compared rates of non-accidental mortality/hospital admission (composite primary outcome) during 12 months of follow-up. Secondary analyses considered non-accidental admission and mortality as separate outcomes. Potential effect modifiers identified in prior studies including sex, season, and timing of the first routine OPV dose (OPV0, scheduled at birth) were assessed.

RESULTS

Among 10,175 children (5288 in 111 intervention clusters/4887 in 111 control clusters), we observed 265 deaths/admissions during 7616 person-years at risk (intervention: 129; control: 136). C-OPV did not reduce the composite endpoint, hazard ratio (HR): 0.87, 95%CI: 0.68-1.12 or its separate components. C-OPV reduced the risk in children receiving OPV0<15 days of birth (HR=0.66, 95%CI: 0.46-0.95), but not in other children (p for interaction: 0.03). Interactions for other potential effect modifiers were not statistically significant.

CONCLUSIONS

C-OPV had no overall effect on mortality/admissions, but the effect differed by early priming with OPV0.

The Association between Parental Child Vaccination Refusal Rate and the Impact of Mass Vaccination against COVID-19 in Kazakhstan: An Interrupted Time Series Analysis with Predictive Modelling of Nationwide Data Sources from 2013 to 2022

Despite well-established evidence supporting vaccination efficacy in reducing morbidity and mortality among infants and children, there is a global challenge with an increasing number of childhood vaccination refusals. This issue has intensified, especially during the COVID-19 pandemic. Our study aims to forecast mandatory childhood vaccination refusal trends in Kazakhstan until 2030, assessing the impact of mass COVID-19 vaccination on these rates. Utilizing annual official statistical data from 2013 to 2022 provided by the Ministry of Health of Kazakhstan, the study reveals a significant surge in refusals during the pandemic and post-pandemic periods, reaching record levels of 42,282 cases in 2021 and 44,180 cases in 2022. Notably, refusal rates sharply rose in specific regions, like Aktobe (13.9 times increase) and Atyrau (4.29 times increase), emphasizing the need for increased public healthcare attention in these areas. However, despite a decade of data, our forecasting analysis indicates a lack of volatility in childhood vaccine refusal trends for all vaccine types up to 2030, highlighting the statistical significance of the obtained results. The increasing trend in vaccine refusals underscores the necessity to enhance crisis response and support health initiatives, particularly in regions where a substantial rise in refusals has been observed in recent years.

Specific and Nonspecific Effects of Influenza Vaccines

With the introduction of the influenza vaccine in the official immunization schedule of most countries, several data regarding the efficacy, tolerability, and safety of influenza immunization were collected worldwide. Interestingly, together with the confirmation that influenza vaccines are effective in reducing the incidence of influenza virus infection and the incidence and severity of influenza disease, epidemiological data have indicated that influenza immunization could be useful for controlling antimicrobial resistance (AMR) development. Knowledge of the reliability of these findings seems essential for precise quantification of the clinical relevance of influenza immunization. If definitively confirmed, these findings can have a relevant impact on influenza vaccine development and use. Moreover, they can be used to convince even the most recalcitrant health authorities of the need to extend influenza immunization to the entire population. In this narrative review, present knowledge regarding these particular aspects of influenza immunization is discussed. Literature analysis showed that the specific effects of influenza immunization are great enough per se to recommend systematic annual immunization of younger children, old people, and all individuals with severe chronic underlying diseases. Moreover, influenza immunization can significantly contribute to limiting the emergence of antimicrobial resistance. The problem of the possible nonspecific effects of influenza vaccines remains unsolved. The definition of their role as inducers of trained immunity seems essential not only to evaluate how much they play a role in the prevention of infectious diseases but also to evaluate whether they can be used to prevent and treat clinical conditions in which chronic inflammation and autoimmunity play a fundamental pathogenetic role.

Do vaccines increase or decrease susceptibility to diseases other than those they protect against?

Contrary to the long-held belief that the effects of vaccines are specific for the disease they were created; compelling evidence has demonstrated that vaccines can exert positive or deleterious non-specific effects (NSEs). In this review, we compiled research reports from the last 40 years, which were found based on the PubMed search for the epidemiological and immunological studies on the non-specific effects (NSEs) of the most common human vaccines. Analysis of information showed that live vaccines induce positive NSEs, whereas non-live vaccines induce several negative NSEs, including increased female mortality associated with enhanced susceptibility to other infectious diseases, especially in developing countries. These negative NSEs are determined by the vaccination sequence, the antigen concentration in vaccines, the type of vaccine used (live vs. non-live), and also by repeated vaccination. We do not recommend stopping using non-live vaccines, as they have demonstrated to protect against their target disease, so the suggestion is that their detrimental NSEs can be minimized simply by changing the current vaccination sequence. High IgG4 antibody levels generated in response to repeated inoculation with mRNA COVID-19 vaccines could be associated with a higher mortality rate from unrelated diseases and infections by suppressing the immune system. Since most COVID-19 vaccinated countries are reporting high percentages of excess mortality not directly attributable to deaths from such disease, the NSEs of mRNA vaccines on overall mortality should be studied in depth.

Do Pentavalent (DTwP-Hib-HBV) vaccines have sex-differential nonspecific effects? An observational study

Vaccines may alter the ability to combat infections unrelated to the target disease, i.e. have "nonspecific effects." The non-live Diphtheria-Tetanus-Pertussis vaccine (DTP) has been associated with increased child mortality, especially for females. In 2008, the DTP-containing Pentavalent vaccine replaced DTP vaccine in Guinea-Bissau. We investigate female relative to male mortality after Penta vaccination. In Guinea-Bissau, Bandim Health Project (BHP) registered children's vaccination and vital status at biannual village visits and provided vaccines. Among children Penta-vaccinated by BHP, we compared mortality of males and females in Cox proportional hazards models. Children aged 6 weeks to 8 months entered the analysis at the date of vaccination and were followed for up to 6 months. Between September 2008 and December 2017, 33,989 children aged 6 weeks to 8 months were under surveillance. Of these 12,753 (females: 6,363; males: 6,390) received Penta by the BHP and entered the study contributing with 19,667 observations. The mortality rate following Penta vaccination was 25.2 per 1,000 person years for females and 26.6 for males, resulting in an adjusted Female/Male mortality rate ratio of (F/M aMRR) 1.01 (0.82-1.25). The association between sex and mortality differed by timeliness of vaccination, F/M aMRR: 0.62 (0.41-0.93) for children vaccinated below median age, and F/M aMRR: 1.38 (0.90-2.13) for children vaccinated above median age. We did not find higher overall mortality in females than males after Penta vaccination. Our findings suggest that mortality differences between males and females following Penta vaccination may depend on timeliness of Penta vaccination.

Effect of national immunisation campaigns with oral polio vaccine on all-cause mortality in children in rural northern Ghana: 20 years of demographic surveillance cohort data

Background

Studies from Guinea-Bissau and Bangladesh have shown that campaigns with oral polio vaccine (C-OPV) may be associated with 25-31% lower child mortality. Between 1996 and 2015, Ghana had 50 national C-OPVs and numerous campaigns with vitamin A supplementation (VAS), and measles vaccine (MV). We investigated whether C-OPVs had beneficial non-specific effects (NSEs) on child survival in northern Ghana.

Methods

We used data from a health and demographic surveillance system in the Navrongo Health Research Centre in rural northern Ghana to examine mortality from day 1-5 years of age. We used Cox models with age as underlying time scale to calculate hazard ratios (HR) for the time-varying covariate "after-campaign" mortality versus "before-campaign" mortality, adjusted for temporal change in mortality, other campaign interventions and stratified for season at risk.

Findings

From 1996 to 2015, 75,610 children were followed for 280,156 person-years between day 1 and 5 years of age. In initial analysis, assuming a common effect across all ages, we did not find that OPV-only campaigns significantly reduced all-cause mortality, the HR being 0.96 (95% CI: 0.88-1.05). However, we subsequently found the HR differed strongly by age group, being 0.92 (0.75-1.13), 1.29 (1.10-1.51), 0.79 (0.66-0.94), 0.67 (0.53-0.86) and 1.03 (0.78-1.36) respectively for children aged 0-2, 3-5, 6-8, 9-11 and above 12 months of age (p < 0.001). Triangulation of the evidence from this and previous studies suggested that increased frequency of C-OPVs and a different historical period could explain these results.

Interpretation

In Ghana, C-OPVs had limited effects on overall child survival. However, triangulating the evidence suggested that NSEs of C-OPVs depend on age of first exposure and routine vaccination programs. C-OPVs had beneficial effects for children that were not exposed before 6 months of age. These non-specific effects of OPV should be exploited to further reduce child mortality.

Funding

DANIDA; Else og Mogens Wedell Wedellsborgs Fond.

A Matter of the Heart: Why It Is Time to Change How We Talk About Maternal Mortality

As the global burden of disease shifts from "diseases of poverty" such as diarrhea to "diseases of affluence" like diabetes and heart disease, a parallel shift is underway in maternal health. Maternal death from hemorrhage is decreasing, while deaths resulting from exacerbation of underlying chronic disease are on the rise.

Beneficial non-specific effects of live vaccines against COVID-19 and other unrelated infections

Live attenuated vaccines could have beneficial, non-specific effects of protecting against vaccine-unrelated infections, such as BCG protecting against respiratory infection. During the COVID-19 pandemic, testing of these effects against COVID-19 was of interest to the pandemic control programme. Non-specific effects occur due to the broad effects of specific live attenuated vaccines on the host immune system, relying on heterologous lymphocyte responses and induction of trained immunity. Knowledge of non-specific effects has been developed in randomised controlled trials and observational studies with children, but examining of whether the same principles apply to adults and older adults was of interest to researchers during the pandemic. In this Personal View, we aim to define a framework for the analysis of non-specific effects of live attenuated vaccines against vaccine-unrelated infections with pandemic potential using several important concepts. First, study endpoints should prioritise severity of infection and overall patient health rather than incidence of infection only (eg, although several trials found no protection of the BCG vaccine against COVID-19 infection, it is associated with lower overall mortality than placebo). Second, revaccination of an individual with the same live attenuated vaccine could be the most effective strategy against vaccine-unrelated infections. Third, coadministration of several live attenuated vaccines might enhance beneficial non-specific effects. Fourth, the sequence of vaccine administration matters; the live attenuated vaccine should be the last vaccine administered before exposure to the pandemic infection and non-live vaccines should not be administered afterwards. Fifth, live attenuated vaccines could modify the immune response to specific COVID-19 vaccines. Finally, non-specific effects of live attenuated vaccines should always be analysed with subgroup analysis by sex of individuals receiving the vaccines.

Oral Polio Vaccine to Mitigate the Risk of Illness and Mortality During the Coronavirus Disease 2019 Pandemic: A Cluster-Randomized Trial in Guinea-Bissau

Background

Oral polio vaccine (OPV) may improve resistance to non-polio-infections. We tested whether OPV reduced the risk of illness and mortality before coronavirus disease 2019 (COVID-19) vaccines were available.

Methods

During the early COVID-19 pandemic, houses in urban Guinea-Bissau were randomized 1:1 to intervention or control. Residents aged 50+ years were invited to participate. Participants received bivalent OPV (single dose) or nothing. Rates of mortality, admissions, and consultation for infections (primary composite outcome) during 6 months of follow-up were compared in Cox proportional hazards models adjusted for age and residential area. Secondary outcomes included mortality, admissions, consultations, and symptoms of infection.

Results

We followed 3726 participants (OPV, 1580; control, 2146) and registered 66 deaths, 97 admissions, and 298 consultations for infections. OPV did not reduce the risk of the composite outcome overall (hazard ratio [HR] = 0.97; 95% confidence interval [CI], .79–1.18). OPV reduced the risk in males (HR = 0.71; 95% CI, .51–.98) but not in females (HR = 1.18; 95% CI, .91–1.52) (P for same effect = .02). OPV also reduced the risk in Bacillus Calmette-Guérin scar-positive (HR = 0.70; 95% CI, .49–.99) but not in scar-negative participants (HR = 1.13; 95% CI, .89–1.45) (P = .03). OPV had no overall significant effect on mortality (HR = 0.96; 95% CI, .59–1.55), admissions (HR = 0.76; 95% CI, .49–1.17) or recorded consultations (HR = 0.99; 95% CI, .79–1.25), but the OPV group reported more episodes with symptoms of infection (6050 episodes; HR = 1.10 [95% CI, 1.03–1.17]).

Conclusions

In line with previous studies, OPV had beneficial nonspecific effects in males.

Stopping Oral Polio Vaccine (OPV) After Defeating Poliomyelitis in Low- and Middle-Income Countries: Harmful Unintended Consequences? Review of the Nonspecific Effects of OPV

Background

The live vaccines bacille Calmette-Guérin (BCG) and measles vaccine have beneficial nonspecific effects (NSEs) reducing mortality, more than can be explained by prevention of tuberculosis or measles infection. Live oral polio vaccine (OPV) will be stopped after polio eradication; we therefore reviewed the potential NSEs of OPV.

Methods

OPV has been provided in 3 contexts: (1) coadministration of OPV and diphtheria-tetanus-pertussis (DTP) vaccine at 6, 10, and 14 weeks of age; (2) at birth (OPV0) with BCG; and (3) in OPV campaigns (C-OPVs) initiated to eradicate polio infection. We searched PubMed and Embase for studies of OPV with mortality as an outcome. We used meta-analysis to obtain the combined relative risk (RR) of mortality associated with different uses of OPV.

Results

First, in natural experiments when DTP was missing, OPV-only compared with DTP + OPV was associated with 3-fold lower mortality in community studies (RR, 0.33 [95% confidence interval {CI}, .14-.75]) and a hospital study (RR, 0.29 [95% CI, .11-.77]). Conversely, when OPV was missing, DTP-only was associated with 3-fold higher mortality than DTP + OPV (RR, 3.23 [95% CI, 1.27-8.21]). Second, in a randomized controlled trial, BCG + OPV0 vs BCG + no OPV0 was associated with 32% (95% CI, 0-55%) lower infant mortality. Beneficial NSEs were stronger with early use of OPV0. Third, in 5 population-based studies from Guinea-Bissau and Bangladesh, the mortality rate was 24% (95% CI, 17%-31%) lower after C-OPVs than before C-OPVs.

Conclusions

There have been few clinical polio cases reported in this century, and no confounding factors or bias would explain all these patterns. The only consistent interpretation is that OPV has beneficial NSEs, reducing nonpolio child mortality.

Vaccination With Oral Polio Vaccine Reduces COVID-19 Incidence

Background

Effective response to emerging pandemic threats is complicated by the need to develop specific vaccines and other medical products. The availability of broadly specific countermeasures that could be deployed early in the pandemic could significantly alter its course and save countless lives. Live attenuated vaccines (LAVs) were shown to induce non-specific protection against a broad spectrum of off-target pathogens by stimulating innate immune responses. The purpose of this study was to evaluate the effect of immunization with bivalent Oral Poliovirus Vaccine (bOPV) on the incidence of COVID-19 and other acute respiratory infections (ARIs).

Methods and Findings

A randomized parallel-group comparative study was conducted in Kirov Medical University. 1115 healthy volunteers aged 18 to 65 were randomized into two equal groups, one of which was immunized orally with a single dose of bOPV “BiVac Polio” and another with placebo. The study participants were monitored for three months for respiratory illnesses including COVID-19. The endpoint was the incidence of acute respiratory infections and laboratory confirmed COVID-19 in both groups during 3 months after immunization. The number of laboratory-confirmed cases of COVID-19 was significantly lower in the vaccinated group than in placebo (25 cases vs. 44, p=0.036). The difference between the overall number of clinically diagnosed respiratory illnesses in the two groups was not statistically significant.

Conclusions

Immunization with bOPV reduced the number of laboratory-confirmed COVID-19 cases, consistent with the original hypothesis that LAVs induce non-specific protection against off-target infections. The findings are in line with previous observations of the protective effects of OPV against seasonal influenza and other viral and bacterial pathogens. The absence of a statistically significant effect on the total number of ARIs may be due to the insufficient number of participants and heterogeneous etiology of ARIs. OPV could be used to complement specific coronavirus vaccines, especially in regions of the world where the vaccines are unavailable, and as a stopgap measure for urgent response to future emerging infections. Clinical trial registration number NCT05083039 at clinicaltrals.gov https://clinicaltrials.gov/ct2/show/NCT05083039?term=NCT05083039&draw=2&rank=1

Understanding the child mortality decline in Guinea-Bissau: the role of population-level nutritional status measured by mid-upper arm circumference

BACKGROUND

Malnutrition is considered an important contributing factor to child mortality, and the mid-upper arm circumference (MUAC) is regarded as one of the better anthropometric predictors of child mortality. We explored whether the decline in child mortality over recent decades could be explained by changes in children's MUAC.

METHODS

This prospective study analysed individual-level data from 47 731 children from the capital of Guinea-Bissau followed from 3 months until 36 months of age over 2003 to 2016. We used standardization to compare the mortality rate as if only the MUAC distribution had changed between an early period (2003-05) and a late period (2014-16). We adjusted the analyses for age, sex, socioeconomic-related possessions and maternal education.

RESULTS

A total of 949 deaths were included in the analysis. The adjusted mortality rate was 18.9 [95% confidence interval (CI) 14.3-23.3] deaths per 1000 person-years (pyrs) in the early period and declined to 4.4 (95% CI 2.9-6.0) deaths per 1000 pyrs in the late period, a 77% (95% CI 71-83%) reduction in the mortality rate. At all calendar years, the MUAC distribution in the population was close to the WHO reference population. MUAC below -1 z-score was associated with increased child mortality. The change in MUAC distribution from the early period to the late period (in the early period mortality standardization) corresponded to 1.5 (95% CI 1.0-2.2) fewer deaths per 1000 pyrs, equivalent to 11% (95% CI 7-14%) of the observed change in child mortality.

CONCLUSIONS

From 2003 to 2016, child mortality in urban Guinea-Bissau declined considerably but, though a low MUAC was associated with increased mortality, changes in the MUAC distribution in the population explained little of the decline. Understanding the driving factors of child mortality decline can help scope tomorrow's interventions.

Trained immunity: implications for vaccination

The concept that only adaptive immunity can build immunological memory has been challenged in the past decade. Live attenuated vaccines such as the Bacillus Calmette-Guérin, measles-containing vaccines, and the oral polio vaccine have been shown to reduce overall mortality beyond their effects attributable to the targeted diseases. After an encounter with a primary stimulus, epigenetic and metabolic reprogramming of bone marrow progenitor cells and functional changes of tissue immune cell populations result in augmented immune responses against a secondary challenge. This process has been termed trained immunity. This review describes the mechanisms leading to trained immunity and summarizes the most important developments from the past few years.

COVID-19 vaccine development based on recombinant viral and bacterial vector systems: combinatorial effect of adaptive and trained immunity

Severe acute respiratory syndrome coronavirus 2 virus (SARS-CoV-2) infection, which causes coronavirus disease 2019 (COVID-19), has led to many cases and deaths worldwide. Therefore, a number of vaccine candidates have been developed to control the COVID-19 pandemic. Of these, to date, 21 vaccines have received emergency approval for human use in at least one country. However, the recent global emergence of SARS-CoV-2 variants has compromised the efficacy of the currently available vaccines. To protect against these variants, the use of vaccines that modulate T cell-mediated immune responses or innate immune cell memory function, termed trained immunity, is needed. The major advantage of a vaccine that uses bacteria or viral systems for the delivery of COVID-19 antigens is the ability to induce both T cell-mediated and humoral immune responses. In addition, such vaccine systems can also exert off-target effects via the vector itself, mediated partly through trained immunity; compared to other vaccine platforms, suggesting that this approach can provide better protection against even vaccine escape variants. This review presents the current status of the development of COVID-19 vaccines based on recombinant viral and bacterial delivery systems. We also discuss the current status of the use of licensed live vaccines for other infections, including BCG, oral polio and MMR vaccines, to prevent COVID-19 infections.

Infectious Diseases-Related Hospitalizations During Oral Polio Vaccine(OPV) and non-OPV immunization periods: An Empirical Evaluation of all Hospital Discharges in California(1985-2010)

BACKGROUND

Live attenuated vaccines such as oral polio vaccine (OPV) can stimulate innate immunity and may have off-target protective effects on other pathogens. We aimed to address this hypothesis by examining changes in infectious diseases (ID)-related hospitalizations in all hospital discharges in California during OPV-(1985-1996) and non-OPV-immunization periods (2000-2010).

METHODS

We searched the OSHPD (Office of Statewide Health Planning and Development) database for all hospital discharges with any ID-related discharge diagnosis code during 1985-2010. We compared the proportion of ID-related hospitalizations (with at least one ID-related discharge diagnosis) among total hospitalizations during OPV immunization (1985-1996) vs non-OPV immunization (2000-2010) periods.

RESULTS

There were 19,281,039 ID-related hospitalizations (8,464,037 with an ID-related discharge-diagnosis as the principal discharge diagnosis for the hospitalization) among 98,117,475 hospitalizations in 1985-2010; 9,520,810 ID-hospitalizations/43,456,484 total hospitalizations in 2000-2010 vs 7,526,957/43,472,796 in 1985-1996. The RR for ID-related hospitalizations in 2000-2010 vs 1985-1996 was 1.27(95% CI: 1.26-1.27) for all diagnoses and 1.15(95% CI: 1.15-1.16) for principal diagnoses. Increases also existed in the proportion of lower respiratory and gastrointestinal infections.

DISCUSSION

The proportion of ID-related hospitalizations was lower in the OPV-immunization period compared to the period after OPV was discontinued. When focused only on hospitalizations with ID as the principal discharge diagnosis the signal remained significant but was smaller. These findings require replication in additional studies.

Heterologous vaccination interventions to reduce pandemic morbidity and mortality: Modeling the US winter 2020 COVID-19 wave

COVID-19 remains a stark health threat worldwide, in part because of minimal levels of targeted vaccination outside high-income countries and highly transmissible variants causing infection in vaccinated individuals. Decades of theoretical and experimental data suggest that nonspecific effects of non-COVID-19 vaccines may help bolster population immunological resilience to new pathogens. These routine vaccinations can stimulate heterologous cross-protective effects, which modulate nontargeted infections. For example, immunization with Bacillus Calmette-Guérin, inactivated influenza vaccine, oral polio vaccine, and other vaccines have been associated with some protection from SARS-CoV-2 infection and amelioration of COVID-19 disease. If heterologous vaccine interventions (HVIs) are to be seriously considered by policy makers as bridging or boosting interventions in pandemic settings to augment nonpharmaceutical interventions and specific vaccination efforts, evidence is needed to determine their optimal implementation. Using the COVID-19 International Modeling Consortium mathematical model, we show that logistically realistic HVIs with low (5 to 15%) effectiveness could have reduced COVID-19 cases, hospitalization, and mortality in the United States fall/winter 2020 wave. Similar to other mass drug administration campaigns (e.g., for malaria), HVI impact is highly dependent on both age targeting and intervention timing in relation to incidence, with maximal benefit accruing from implementation across the widest age cohort when the pandemic reproduction number is >1.0. Optimal HVI logistics therefore differ from optimal rollout parameters for specific COVID-19 immunizations. These results may be generalizable beyond COVID-19 and the US to indicate how even minimally effective heterologous immunization campaigns could reduce the burden of future viral pandemics.

Immune Memory in Aging: a Wide Perspective Covering Microbiota, Brain, Metabolism, and Epigenetics

Non-specific innate and antigen-specific adaptive immunological memories are vital evolutionary adaptations that confer long-lasting protection against a wide range of pathogens. Adaptive memory is established by memory T and B lymphocytes following the recognition of an antigen. On the other hand, innate immune memory, also called trained immunity, is imprinted in innate cells such as macrophages and natural killer cells through epigenetic and metabolic reprogramming. However, these mechanisms of memory generation and maintenance are compromised as organisms age. Almost all immune cell types, both mature cells and their progenitors, go through age-related changes concerning numbers and functions. The aging immune system renders the elderly highly susceptible to infections and incapable of mounting a proper immune response upon vaccinations. Besides the increased infectious burden, older individuals also have heightened risks of metabolic and neurodegenerative diseases, which have an immunological component. This review discusses how immune function, particularly the establishment and maintenance of innate and adaptive immunological memory, regulates and is regulated by epigenetics, metabolic processes, gut microbiota, and the central nervous system throughout life, with a focus on old age. We explain in-depth how epigenetics and cellular metabolism impact immune cell function and contribute or resist the aging process. Microbiota is intimately linked with the immune system of the human host, and therefore, plays an important role in immunological memory during both homeostasis and aging. The brain, which is not an immune-isolated organ despite former opinion, interacts with the peripheral immune cells, and the aging of both systems influences the health of each other. With all these in mind, we aimed to present a comprehensive view of the aging immune system and its consequences, especially in terms of immunological memory. The review also details the mechanisms of promising anti-aging interventions and highlights a few, namely, caloric restriction, physical exercise, metformin, and resveratrol, that impact multiple facets of the aging process, including the regulation of innate and adaptive immune memory. We propose that understanding aging as a complex phenomenon, with the immune system at the center role interacting with all the other tissues and systems, would allow for more effective anti-aging strategies.

Oral Polio Vaccine Campaigns May Reduce the Risk of Death from Respiratory Infections

Oral polio vaccine (OPV) campaigns, but not other campaigns, have been associated with major reductions in child mortality. Studies have shown that OPV reduces the risk of respiratory infections. We analysed the causes of death at 0–2 years of age in Chakaria, a health and demographic surveillance Systems in Bangladesh, in the period 2012–2019 where 13 national campaigns with combinations of OPV (n = 4), vitamin A supplementation (n = 9), measles vaccine (MV) (n = 2), and albendazole (n = 2) were implemented. OPV-only campaigns reduced overall mortality by 30% (95% confidence interval: −10–56%). Deaths from respiratory infections were reduced by 62% (20–82%, p = 0.01) in the post-neonatal period (1–35 months), whereas there was as slight increase of 19% (−37–127%, p = 0.54) for deaths from other causes. There was no benefit of other types of campaigns. Hence, the hypothesis that OPV may have beneficial non-specific effects, protecting particularly against respiratory infections, was confirmed.