Modeling Respiratory Syncytial Virus Adult Vaccination in the United States With a Dynamic Transmission Model

BACKGROUND

Respiratory syncytial virus (RSV) is shown to cause substantial morbidity, hospitalization, and mortality in infants and older adults. Population-level modeling of RSV allows to estimate the full burden of disease and the potential epidemiological impact of novel prophylactics.

METHODS

We modeled the RSV epidemiology in the United States across all ages using a deterministic compartmental transmission model. Population-level symptomatic RSV acute respiratory tract infection (ARI) cases were projected across different natural history scenarios with and without vaccination of adults aged ≥60 years. The impact of vaccine efficacy against ARIs, infectiousness and vaccine coverage on ARI incidence were assessed. The impact on medical attendance, hospitalization, complications, death, and other outcomes was also derived.

RESULTS

Without a vaccine, we project 17.5-22.6 million symptomatic RSV ARI cases annually in adults aged ≥18 years in the US, with 3.6-4.8 million/year occurring in adults aged ≥60 years. Modeling indicates that up to 2.0 million symptomatic RSV-ARI cases could be prevented annually in ≥60-year-olds with a hypothetical vaccine (70% vaccine efficacy against symptomatic ARI and 60% vaccine coverage) and that up to 0.69 million/year could be prevented in the nonvaccinated population, assuming 50% vaccine impact on infectiousness.

CONCLUSIONS

The model provides estimated burden of RSV in the US across all age groups, with substantial burden projected specifically in older adults. Vaccination of adults aged ≥60 years could significantly reduce the burden of disease in this population, with additional indirect effect in adults aged <60 years due to reduced transmissibility.

Cost analysis of Down syndrome screening in advanced maternal age

OBJECTIVE

To analyze the potential cost and efficacy of Down syndrome screening in the population with advanced maternal age.

METHODS

Three screening methods defining Down syndrome risk for women with advanced maternal age were analyzed: advanced maternal age; advanced maternal age and maternal serum triple screen; and advanced maternal age, maternal serum triple screen and genetic sonogram. Costs for all tests and procedures were estimated. Procedure-related loss for amniocentesis was assumed to be 1:200. Efficacy was defined as: number of amniocenteses performed, number of Down syndrome cases detected, procedure-related losses, Down syndrome cases detected per fetal loss, cost per Down syndrome case detected and total cost of screening.

RESULTS

In 1999 in the USA, there were 530,610 women with advanced maternal age at 16 weeks' gestation carrying an estimated 4,043 fetuses with Down syndrome. Screening by maternal age alone would result in the 100% detection of Down syndrome cases, but would require over 530,000 amniocenteses and result in 2,653 procedure-related losses. Combining age with serum screen and genetic sonogram would detect 97.6% of Down syndrome cases, but would require only 119,791 amniocenteses and result in 599 procedure-related losses. The projected cost per Down syndrome case detected using age screening is 219,109 dollars versus 155,992 dollars using serum screen and genetic sonogram.

CONCLUSIONS

The combination of advanced maternal age, maternal serum screen and genetic sonogram would result in the fewest procedure-related losses and lowest cost per Down syndrome case detected.

Pulmonary function subsequent to expiratory muscle fatigue in healthy humans

One of the mechanisms proposed to explain the decrement in pulmonary function often seen after exercise is fatigue of the expiratory muscles. To test the hypothesis that expiratory muscle fatigue alters lung function, several indices of pulmonary function were measured before and after expiratory muscle fatigue was induced by expiratory loaded breathing. Eight subjects completed a fatigue trial (EF) in which expiratory threshold loaded breathing was performed at an initial resistance equal to 80 % of their maximal expiratory pressure (MEP), at a respiratory rate of 13 bpm, and a duty cycle (T(I)/T(Tot)) of 0.33. MEP was taken at predefined intervals throughout the loaded breathing protocol, and loaded breathing was discontinued when MEP was less than 80 % of each subject's pre EF trial MEP (T(Lim)). FVC, FEV(1.0), FEF(25 %), FEF(25-75 %), and maximal inspiratory and expiratory pressures (MIP and MEP) were taken prior to, immediately after, and at 5, 10, and 15 min post fatigue. On a separate day a control trial (CON) was performed that was identical to each subjects EF trial with the exception that no expiratory load was utilized. At T(Lim) MEP was significantly reduced (p < 0.001) by 23.5 % from the pre-expiratory loaded breathing value (183.1 +/- 39.56 to 140.13 +/- 30.45 mmHg), whereas it remained unchanged during the CON trial (191.06 +/- 44.18 to 188.06 +/- 43.50 mmHg). FVC measured prior to and immediately after T(Lim) remained unchanged following both the EF (5349.45 +/- 1130.8 to 5387.43 +/- 1139.92 mL) and CON trials (5287.75 +/- 1220.29 and 5352.78 +/- 1191.30 mL). These results suggest that any expiratory muscle fatigue developed during exercise by itself does not result in altered pulmonary function. However, any interactions between expiratory muscle fatigue and other consequences of exercise that may alter lung function cannot be ruled out.

Perceptual reactance and task performance

57 female subjects participated in a study in which perceptual reactance was assessed by the kinesthetic figural aftereffects test. Subjects identified as augmenters were quicker than reducers on a disjunctive reaction time task and a significant interactive effect was found on a paired-associate task. Augmenters performed better on a similar list while reducers were more effective on a dissimilar list.

The errant spouse: a study in person perception

College students rated protagonists of vignettes involved in extra-marital affairs in two separate studies. In the first study, where the affair resulted in the errant spouse falling in love, both the husband and wife were perceived more favorably when they cheated than when they were being cheated. The results of the second study, where the affair did not involve love, were opposite from those of the first. The cheating spouse was viewed negatively. No significant differences were found between married and unmarried subjects' perceptions. Results indicated that the motivation for an extramarital affair may be crucial in evaluation. Implications of perceived competence of the spouse were considered.

Perceptual reactance and melanic density

Following assessment of eye color, a total of 108 college students (33 males and 75 females) estimated changes in sizes of standardized blocks while blindfolded. Subjects were classfied as perceptual augmenters, moderates or reducers as a function of their overestimation, accurate estimation, or underestimation, respectively, of the sizes of the blocks. A significant interaction of gender by perceptual reactance appeared, with augmenting males being rated the most dark-eyed and augmenting females being rated the most light-eyed. Interpretation of the findings was made in terms of attention to relevant cues.