Infection-Induced Immunity Is Associated With Protection Against Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Decreased Infectivity.

BACKGROUND: The impact of infection-induced immunity on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission has not been well established. Here we estimate the effects of prior infection induced immunity in adults and children on SARS-CoV-2 transmission in households. METHODS: We conducted a household cohort study from March 2020-November 2022 in Managua, Nicaragua; following a housheold SARS-CoV-2 infection, household members are closely monitored for infection. We estimate the association of time period, age, symptoms, and prior infection with secondary attack risk. RESULTS: Overall, transmission occurred in 70.2% of households, 40.9% of household contacts were infected, and the secondary attack risk ranged from 8.1% to 13.9% depending on the time period. Symptomatic infected individuals were more infectious (rate ratio [RR] 21.2, 95% confidence interval [CI]: 7.4-60.7) and participants with a prior infection were half as likely to be infected compared to naïve individuals (RR 0.52, 95% CI:.38-.70). In models stratified by age, prior infection was associated with decreased infectivity in adults and adolescents (secondary attack risk [SAR] 12.3, 95% CI: 10.3, 14.8 vs 17.5, 95% CI: 14.8, 20.7). However, although young children were less likely to transmit, neither prior infection nor symptom presentation was associated with infectivity. During the Omicron era, infection-induced immunity remained protective against infection. CONCLUSIONS: Infection-induced immunity is associated with decreased infectivity for adults and adolescents. Although young children are less infectious, prior infection and asymptomatic presentation did not reduce their infectivity as was seen in adults. As SARS-CoV-2 transitions to endemicity, children may become more important in transmission dynamics.

Anti-Neuraminidase Antibodies Reduce the Susceptibility to and Infectivity of Influenza A/H3N2 Virus.

Immune responses against neuraminidase (NA) are of great interest for developing more robust influenza vaccines, but the role of anti-NA antibodies on influenza infectivity has not been established. We conducted household transmission studies in Managua, Nicaragua to examine the impact of anti-NA antibodies on influenza A/H3N2 susceptibility and infectivity. Analyzing these data with mathematical models capturing household transmission dynamics and their drivers, we estimated that having higher preexisting antibody levels against the hemagglutinin (HA) head, HA stalk, and NA was associated with reduced susceptibility to infection (relative susceptibility 0.67, 95% Credible Interval [CrI] 0.50-0.92 for HA head; 0.59, 95% CrI 0.42-0.82 for HA stalk; and 0.56, 95% CrI 0.40-0.77 for NA). Only anti-NA antibodies were associated with reduced infectivity (relative infectivity 0.36, 95% CrI 0.23-0.55). These benefits from anti-NA immunity were observed even among individuals with preexisting anti-HA immunity. These results suggest that influenza vaccines designed to elicit NA immunity in addition to hemagglutinin immunity may not only contribute to protection against infection but reduce infectivity of vaccinated individuals upon infection.

Comparative risks of all-cause mortality for Veterans with schizophrenia with ongoing receipt of clozapine and other antipsychotic medications.

To guide care for patients with schizophrenia, the Veterans Health Administration (VHA) evaluated the associations between current or recent use of clozapine and all-cause mortality and explored associations for other antipsychotic medications. Using a case-control design, patients with schizophrenia who died in fiscal years 2014-2018 were matched on age, sex, race, and VHA facility to up to 10 controls who were alive on the case's date of death (index date). Medication coverage during the 91 days before the index date was classified as none, partial (1-44 days), and consistent (45-91 days). Medication coverage patterns during the index period were compared to coverage patterns during the period of 92-182 days prior to index date with each medication coverage classified as no change, no coverage, increased, or decreased. Conditional logistic regression analyses controlling for patient characteristics identified no associations of consistent or increasing clozapine coverage with mortality; partial and decreasing coverage were associated with greater mortality and these effects did not differ from those of other the medications considered. Exploratory analyses considering non-clozapine antipsychotic agents suggest that consistent coverage by olanzapine may be associated with increased mortality, that mortality associated with olanzapine may be greater than aripiprazole, and that this effect can be attributed primarily to patients with diabetes. Further study of this topic is needed.

High Co-circulation of Influenza and Severe Acute Respiratory Syndrome Coronavirus 2.

In the first 2 years of the coronavirus disease 2019 pandemic, influenza transmission decreased substantially worldwide, meaning that health systems were not faced with simultaneous respiratory epidemics. In 2022, however, substantial influenza transmission returned to Nicaragua where it co-circulated with severe acute respiratory syndrome coronavirus 2, causing substantial disease burden.

Infection-induced immunity is associated with protection against SARS-CoV-2 infection, but not decreased infectivity during household transmission.

Background: Understanding the impact of infection-induced immunity on SARS-CoV-2 transmission will provide insight into the transition of SARS-CoV-2 to endemicity. Here we estimate the effects of prior infection induced immunity and children on SARS-CoV-2 transmission in households. Methods: We conducted a household cohort study between March 2020-June 2022 in Managua, Nicaragua where when one household member tests positive for SARS-CoV-2, household members are closely monitored for SARS-CoV-2 infection. Using a pairwise survival model, we estimate the association of infection period, age, symptoms, and infection-induced immunity with secondary attack risk. Results: Overall transmission occurred in 72.4% of households, 42% of household contacts were infected and the secondary attack risk was 13.0% (95% CI: 11.7, 14.6). Prior immunity did not impact the probability of transmitting SARS-CoV-2. However, participants with pre-existing infection-induced immunity were half as likely to be infected compared to naïve individuals (RR 0.53, 95% CI: 0.39, 0.72), but this reduction was not observed in children. Likewise, symptomatic infected individuals were more likely to transmit (RR 24.4, 95% CI: 7.8, 76.1); however, symptom presentation was not associated with infectivity of young children. Young children were less likely to transmit SARS-CoV-2 than adults. During the omicron era, infection-induced immunity remained protective against infection. Conclusions: Infection-induced immunity is associated with protection against infection for adults and adolescents. While young children are less infectious, prior infection and asymptomatic presentation did not reduce their infectivity as was seen in adults. As SARS-CoV-2 transitions to endemicity, children may become more important in transmission dynamics. Article summary: Infection-induced immunity protects against SARS-CoV-2 infection for adolescents and adults; however, there was no protection in children. Prior immunity in an infected individual did not impact the probability they will spread SARS-CoV-2 in a household setting.

High co-circulation of influenza and SARS-CoV-2.

In the first two years of the COVID-19 pandemic, influenza transmission decreased substantially worldwide meaning that health systems were not faced with simultaneous respiratory epidemics. In 2022, however, substantial influenza transmission returned to Nicaragua where it co-circulated with SARS-CoV-2 causing substantial disease burden.

Religion and Measles Vaccination in Indonesia, 1991-2017.

INTRODUCTION: Some Muslim religious councils in Indonesia have ruled that measles vaccines contain haram (i.e., forbidden materials). This study evaluates the changes in measles vaccination coverage between 1991 and 2017 and compares vaccination coverage between Muslims and non-Muslims in Indonesia. METHODS: A total of 7 cross-sectional in-person surveys of mothers in 1991-2017 in Indonesia were analyzed in 2019. Participants were asked about religion in 1991-2007, and 100 data sets of religion were imputed for 2012 and 2017. In this multiple imputation analysis, binomial regression models output prevalence differences adjusted for wealth, education, child's sex, and mother's age. A quadratic term for year (year X year) and an interaction term between year and religion evaluated changes in vaccination over time by religion. RESULTS: The 7 data sets included 23,106 children aged 12-23 months, with the proportion of those who were Muslims ranging between 85% and 89% across the survey years. Between 1991 and 2017, measles vaccination coverage increased from 57% to 79% among non-Muslims and from 59% to 79% among Muslims. In the multivariable regression model, measles vaccination coverage increased by 1.6% each year (with a quadratic term of -0.05%, indicating some leveling over time). At baseline in 1991, non-Muslims had a vaccination coverage of 6.2% higher than that of Muslims, but this disparity decreased by -0.2% each year. CONCLUSIONS: Measles vaccination increased in both Muslims and non-Muslims in Indonesia but has stagnated in recent years. Because of increased attention among Muslim groups on haram materials in vaccines since 2017, future studies should continue to examine the relationship between religion and vaccine uptake in Indonesia. SUPPLEMENT INFORMATION: This article is part of a supplement entitled Global Vaccination Equity, which is sponsored by the Global Institute for Vaccine Equity at the University of Michigan School of Public Health.

Demographics of Vaccine Hesitancy in Chandigarh, India.

The impact of vaccine hesitancy on childhood immunization in low- and middle-income countries remains largely uncharacterized. This study describes the sociodemographic patterns of vaccine hesitancy in Chandigarh, India. Mothers of children <5 years old were sampled from a two-stage cluster, systematic sample based on Anganwadi child care centers in Chandigarh. Vaccine hesitancy was measured using a 10-item Vaccine Hesitancy Scale, which was dichotomized. A multivariable logistic regression assessed the association between socioeconomic factors and vaccine hesitancy score. Among 305 mothers, >97% of mothers thought childhood vaccines were important, effective, and were a good way to protect against disease. However, many preferred their child to receive fewer co-administered vaccines (69%), and were concerned about side effects (39%). Compared to the "other caste" group, scheduled castes or scheduled tribes had 3.48 times greater odds of vaccine hesitancy (95% CI: 1.52, 7.99). Those with a high school education had 0.10 times the odds of vaccine hesitancy compared to those with less education (95% CI: 0.02, 0.61). Finally, those having more antenatal care visits were less vaccine hesitant (≥4 vs. <4 visits OR: 0.028, 95% CI: 0.1, 0.76). As India adds more vaccines to its Universal Immunization Program, consideration should be given to addressing maternal concerns about vaccination, in particular about adverse events and co-administration of multiple vaccines.