Showing posts with label covid. Show all posts
Showing posts with label covid. Show all posts

Tuesday, February 13, 2024

Incentives to take tests and get vaccinated

 As the pandemic phase of Covid-19 recedes, we can reflect on what we've learned about demand for tests and for vaccines.   Here's a paper from a year ago that I missed at the time  that discusses incentives and defaults.

Incentives and Defaults Can Increase COVID-19 Vaccine Intentions and Test Demand, by Marta Serra-Garcia and Nora Szech, Management Science, Vol. 69, No. 2, February 2023, Pages 723-1322, iii-iv

Abstract: Willingness to vaccinate and test are critical in the COVID-19 pandemic. We study the effects of two measures to increase the support of vaccination and testing: defaults and monetary compensations. Some organizations, such as restaurants, fire departments, hospitals, or governments in some countries, have used these measures. Yet there is the concern that compensations could erode intrinsic motivation and decrease vaccination intentions. We show that, in the early stages of the pandemic, both approaches, compensations and defaults, significantly increased COVID-19 test demand and vaccine intentions. Compensations for vaccines, however, need to be large enough because low compensations can backfire. We estimate heterogeneous treatment effects to document which groups are more likely to respond to these measures. The results show that defaults and avoidance of small compensations are especially important for individuals who are more skeptical of the vaccine, measured by their trust in the vaccine and their political views. Hence, both measures could be used in a targeted manner to achieve stronger results.

Monday, December 4, 2023

Convalescent plasma: the picture is getting clearer

 Slowly, there is evidence accumulating that convalescent plasma is helpful in treating patients with severe Covid, if it is administered early.  There is also evidence that it doesn't help much once the disease has become well established, particularly when the primary symptoms become due to the body's own immune reaction.  These caveats help explain why early reports did not find an effect of convalescent plasma--i.e. it helped only a subset of the patients to whom it was administered. But for those it was sometimes life saving. Here is a recent paper from the New England Journal of Medicine.

Convalescent Plasma for Covid-19–Induced ARDS in Mechanically Ventilated Patients by Benoît Misset, M.D., Michael Piagnerelli, M.D., Ph.D., Eric Hoste, M.D., Ph.D., Nadia Dardenne, M.Sc., David Grimaldi, M.D., Ph.D., Isabelle Michaux, M.D., Ph.D., Elisabeth De Waele, M.D., Ph.D., Alexander Dumoulin, M.D., Philippe G. Jorens, M.D., Ph.D., Emmanuel van der Hauwaert, M.D., Frédéric Vallot, M.D., Stoffel Lamote, M.D., et al., October 26, 2023, N Engl J Med 2023; 389:1590-1600 DOI: 10.1056/NEJMoa2209502

"Abstract

BACKGROUND

Passive immunization with plasma collected from convalescent patients has been regularly used to treat coronavirus disease 2019 (Covid-19). Minimal data are available regarding the use of convalescent plasma in patients with Covid-19–induced acute respiratory distress syndrome (ARDS).

METHODS

In this open-label trial, we randomly assigned adult patients with Covid-19–induced ARDS who had been receiving invasive mechanical ventilation for less than 5 days in a 1:1 ratio to receive either convalescent plasma with a neutralizing antibody titer of at least 1:320 or standard care alone. Randomization was stratified according to the time from tracheal intubation to inclusion. The primary outcome was death by day 28.

RESULTS

A total of 475 patients underwent randomization from September 2020 through March 2022. Overall, 237 patients were assigned to receive convalescent plasma and 238 to receive standard care. Owing to a shortage of convalescent plasma, a neutralizing antibody titer of 1:160 was administered to 17.7% of the patients in the convalescent-plasma group. Glucocorticoids were administered to 466 patients (98.1%). At day 28, mortality was 35.4% in the convalescent-plasma group and 45.0% in the standard-care group (P=0.03). In a prespecified analysis, this effect was observed mainly in patients who underwent randomization 48 hours or less after the initiation of invasive mechanical ventilation. Serious adverse events did not differ substantially between the two groups.

CONCLUSIONS

The administration of plasma collected from convalescent donors with a neutralizing antibody titer of at least 1:160 to patients with Covid-19–induced ARDS within 5 days after the initiation of invasive mechanical ventilation significantly reduced mortality at day 28. This effect was mainly observed in patients who underwent randomization 48 hours or less after ventilation initiation."

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Here are my posts on convalescent plasma, and the confusing initial reports about its effects.

Monday, September 4, 2023

Covid medication: allocation, information, hesitancy, and uptake: what are some things we have learned?

 I've posted before about how informational advertising about vaccine availability and safety seems to have had a positive effect on vaccination rates among disadvantaged populations. There was particular concern in the U.S. at one point that Black people were less likely to receive vaccines and other medications than other Americans.

Today's post collects several papers about the effect of randomly allocating invitations for temporarily scarce Covid medications, while giving members of disadvantaged groups a higher probability of receiving an invitation.  Included will be an editorial warning us that we shouldn't be satisfied to judge the outcome of a market design by its intended outcome ("Moving Beyond Intent and Realizing Health Equity").

There are market design lessons in these last few years of Covid experience that I hope will help make the responses to future pandemics more effective. Not least of these is that the allocation of public health  and medical resources turns out to be quite different from  the allocation of other kinds of resources, in many important ways that reflect the broader economic and social environments in which different kinds of allocation takes place.

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Here's a paper in the most recent issue of JAMA Health Forum, by a team that includes both medical professionals and market designers.

Weighted Lottery to Equitably Allocate Scarce Supply of COVID-19 Monoclonal Antibody , by Erin K. McCreary, PharmD1; Utibe R. Essien, MD, MPH2,3; Chung-Chou H. Chang, PhD4,5; Rachel A. Butler, MHA, MPH6; Parag Pathak, PhD7; Tayfun Sönmez, PhD8; M. Utku Ünver, PhD8; Ashley Steiner, BS9; Maddie Chrisman, PT, DPT10; Derek C. Angus, MD, MPH11; Douglas B. White, MD, MAS11, JAMA Health Forum. 2023;4(9):e232774. Sept. 1, doi:10.1001/jamahealthforum.2023.2774 

"Objective  To describe the development and use of a weighted lottery to allocate a scarce supply of tixagevimab with cilgavimab as preexposure prophylaxis to COVID-19 for immunocompromised individuals and examine whether this promoted equitable allocation to disadvantaged populations.

"Design, Setting, and Participants  This quality improvement study analyzed a weighted lottery process from December 8, 2021, to February 23, 2022, that assigned twice the odds of drug allocation of 450 tixagevimab with cilgavimab doses to individuals residing in highly disadvantaged neighborhoods according to the US Area Deprivation Index (ADI) in a 35-hospital system in Pennsylvania, New York, and Maryland. In all, 10 834 individuals were eligible for the lottery. Weighted lottery results were compared with 10 000 simulated unweighted lotteries in the same cohort performed after drug allocation occurred.

"Main Outcomes:  Proportion of individuals from disadvantaged neighborhoods and Black individuals who were allocated and received tixagevimab with cilgavimab.

"Results:  Of the 10 834 eligible individuals, 1800 (16.6%) were from disadvantaged neighborhoods and 767 (7.1%) were Black. Mean (SD) age was 62.9 (18.8) years, and 5471 (50.5%) were women. A higher proportion of individuals from disadvantaged neighborhoods was allocated the drug in the ADI-weighted lottery compared with the unweighted lottery (29.1% vs 16.6%; P < .001). The proportion of Black individuals allocated the drug was greater in the weighted lottery (9.1% vs 7.1%; P < .001). Among the 450 individuals allocated tixagevimab with cilgavimab in the ADI-weighted lottery, similar proportions of individuals from disadvantaged neighborhoods accepted the allocation and received the drug compared with those from other neighborhoods (27.5% vs 27.9%; P = .93). However, Black individuals allocated the drug were less likely to receive it compared with White individuals (3 of 41 [7.3%] vs 118 of 402 [29.4%]; P = .003).

...

"Conclusions and Relevance:  The findings of this quality improvement study suggest an ADI-weighted lottery process to allocate scarce resources is feasible in a large health system and resulted in more drug allocation to and receipt of drug by individuals who reside in disadvantaged neighborhoods. Although the ADI-weighted lottery also resulted in more drug allocation to Black individuals compared with an unweighted process, they were less likely to accept allocation and receive it compared with White individuals. Further strategies are needed to ensure that Black individuals receive scarce medications allocated."

...

"The lottery was repeated over several weeks, but we chose to examine only the first assignment. The interpretation of later rounds is problematic because eventually all individuals were offered tixagevimab with cilgavimab. By focusing on the first draw, we can specifically evaluate whether the intent of the lottery was met."

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Closely related reports:

White, D.B., McCreary, E.K., Chang, C.C.H., Schmidhofer, M., Bariola, J.R., Jonassaint, N.N., Persad, G., Truog, R.D., Pathak, P., Sonmez, T. and Unver, M.U., 2022. A multicenter weighted lottery to equitably allocate scarce COVID-19 therapeutics. American Journal of Respiratory and Critical Care Medicine, 206(4), pp.503-506.

Rubin, E., Dryden-Peterson, S.L., Hammond, S.P., Lennes, I., Letourneau, A.R., Pathak, P., Sonmez, T. and Ünver, M.U., 2021. A novel approach to equitable distribution of scarce therapeutics: institutional experience implementing a reserve system for allocation of COVID-19 monoclonal antibodies. Chest, 160(6), pp.2324-2331.*

White, D.B. and Angus, D.C., 2020. A proposed lottery system to allocate scarce COVID-19 medications: promoting fairness and generating knowledge. Jama, 324(4), pp.329-330.

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And here's an editorial in the same issue of JAMA Health Forum as the most recent article, pointing out that less-disadvantaged patients among those living in census blocks identified as disadvantaged (in particular  commercially insured and White patients) were much more likely to receive the treatment:

Moving Beyond Intent and Realizing Health Equity, by Atheendar S. Venkataramani, MD, PhD, Invited Commentary, September 1, 2023, JAMA Health Forum. 2023;4(9):e232525. doi:10.1001/jamahealthforum.2023.2525

"In a study published in this issue of JAMA Health Forum, McCreary and colleagues3 report on a landmark effort at the University of Pittsburgh Medical Center (UPMC) to distribute equitably a scarce monoclonal antibody resource, tixagevimab with cilgavimab, for COVID-19 preexposure prophylaxis in immunocompromised individuals. In December 2021, UPMC received an allotment of 450 doses of tixagevimab with cilgavimab from the Pennsylvania Department of Health to cover a large health system with 35 hospitals and 800 outpatient facilities through February 2022. In an ex ante effort to mitigate health disparities and respond to guidance from the Commonwealth of Pennsylvania to allocate scarce resources in a manner that accounts for multiple ethical objectives, UPMC convened an advisory group of clinicians, community stakeholders, and experts in community outreach.

...

"The lottery was constructed using the Area Deprivation Index (ADI) to ensure that patients in highly disadvantaged neighborhoods had an equal opportunity to access tixagevimab with cilgavimab. Patients living in neighborhoods with ADIs above a specific cutoff that has been shown to best target less affluent, rural, and Black patients received 2 entries in the lottery, compared with 1 entry for patients in more advantaged neighborhoods. In their study, McCreary and colleagues3 found that this process resulted in equitable access: similar proportions of individuals in more advantaged and more disadvantaged neighborhoods (about 28% in each group) received tixagevimab with cilgavimab during the study period, although Black patients who were allocated the drug in the lottery were significantly less likely to receive it compared with White patients (7.3% vs 29.4%).

...

"Having identified its patient population, UPMC required only patient addresses as well as publicly available data on ADIs to implement the lottery intervention. The ADIs are defined at the census block group level, which include about 1000 residents on average. Thus, UPMC was able to achieve equitable opportunity to access tixagevimab with cilgavimab across small localities with very different socioeconomic profiles.

...

On the other hand, higher-resolution data that specifically measure the types of intersecting, reinforcing, and cumulative disadvantages faced by historically marginalized groups5 may be needed to achieve equitable outcomes across other dimensions, such as race and ethnicity. Within census blocks, patients assigned the same ADI levels but who may have faced relatively fewer structural barriers compared with Black patients or patients receiving Medicaid—namely, commercially insured and White patients—were more likely to access tixagevimab with cilgavimab conditional on being allocated to receive it in the lottery

...

"The lower rates of drug receipt among Black patients also underscores the importance of complementary investments and operational decisions to address additional structural barriers to accessing medical technology.

...

"The study by McCreary and colleagues3 represents the type of courageous and rigorous work that is needed to chart a path forward in determining how best to bridge the access gap for leading-edge medical technology. Future work would benefit from the same type of clarity demonstrated in this study by including clear definitions for how equity should be operationalized, attempting to address fragmentation between clinical services and services that address social drivers of health, aligning incentives, and addressing historical barriers that have made it difficult to achieve health equity."

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*Earlier:

Saturday, August 14, 2021


Monday, March 6, 2023

Reconsideration of covid convalescent plasma

Recently Statnews reported that Covid convalescent plasma (CCP) may in fact be useful in preventing severe illness, despite the fact that earlier clinical trials did not show success in reversing severe illness:

Covid convalescent plasma: the ‘little engine that could’  By Michael J. Joyner, Nigel Paneth and Arturo Casadevall

"Unlike monoclonal antibodies, which can be defeated by new SARS-CoV-2 variants, CCP collected from vaccinated donors after recent breakthrough infections (VaxCCP) evolves with the variants and retains the ability to neutralize them. What makes CCP an even more promising therapy is that there are now many potential donors available in the U.S. who have been vaccinated and had recent breakthrough infections.

...

"An array of data, including randomized controlled trials and careful retrospective studies, show a clear survival benefit when CCP is given to immunocompromised individuals who test positive for SARS-CoV-2. There are also impressive case reports and case series showing that Covid convalescent plasma, especially VaxCCP, is effective in patients with smoldering Covid-19.

...

"the early “major” RCTs that tested the efficacy of CCP on survival in hospitalized patients tested the wrong use case. These studies treated patients who were too sick for too long to benefit from antibody therapy. But the major “negative” trials all showed evidence of effectiveness among people who received CCP earlier, who were not already desperately ill, who were immunocompromised, or who received the most antibodies. Unfortunately, these positive signals, which were consistent with impressive real-world data on Covid-19 and CCP, were buried under the top-line results."

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Earlier posts on convalescent plasma

Tuesday, February 7, 2023

Social media advertising and COVID vaccination, in PNAS

 Vaccine rollout is different than allocating other (initially) scarce goods because it involves overcoming vaccine hesitancy.  Here's a meta-analysis which concludes that advertising was helpful and cost effective.

Athey, Susan, Kristen Grabarz, Michael Luca, and Nils Wernerfelt. "Digital public health interventions at scale: The impact of social media advertising on beliefs and outcomes related to COVID vaccines." Proceedings of the National Academy of Sciences 120, no. 5 (2023): e2208110120.

Abstract: Public health organizations increasingly use social media advertising campaigns in pursuit of public health goals. In this paper, we evaluate the impact of about $40 million of social media advertisements that were run and experimentally tested on Facebook and Instagram, aimed at increasing COVID-19 vaccination rates in the first year of the vaccine roll-out. The 819 randomized experiments in our sample were run by 174 different public health organizations and collectively reached 2.1 billion individuals in 15 languages. We find that these campaigns are, on average, effective at influencing self-reported beliefs—shifting opinions close to 1% at baseline with a cost per influenced person of about $3.41. Combining this result with an estimate of the relationship between survey outcomes and vaccination rates derived from observational data yields an estimated cost per additional vaccination of about $5.68. There is further evidence that campaigns are especially effective at influencing users’ knowledge of how to get vaccines. Our results represent, to the best of our knowledge, the largest set of online public health interventions analyzed to date.

Tuesday, January 24, 2023

"Financial incentives for vaccination do not have negative unintended consequences," in Nature

 Here's a recent article in Nature whose title effectively summarizes its conclusions, and brings some evidence from RCTs to bear on the issue of whether financial incentives corrupt innate values:

Florian H. Schneider, Pol Campos-Mercade, Stephan Meier, Devin Pope, Erik Wengström & Armando N. Meier, "Financial incentives for vaccination do not have negative unintended consequences. Nature (2023). https://doi.org/10.1038/s41586-022-05512-4

Abstract: Financial incentives to encourage healthy and prosocial behaviours often trigger initial behavioural change1,2,3,4,5,6,7,8,9,10,11, but a large academic literature warns against using them12,13,14,15,16. Critics warn that financial incentives can crowd out prosocial motivations and reduce perceived safety and trust, thereby reducing healthy behaviours when no payments are offered and eroding morals more generally17,18,19,20,21,22,23,24. Here we report findings from a large-scale, pre-registered study in Sweden that causally measures the unintended consequences of offering financial incentives for taking the first dose of a COVID-19 vaccine. We use a unique combination of random exposure to financial incentives, population-wide administrative vaccination records and rich survey data. We find no negative consequences of financial incentives; we can reject even small negative impacts of offering financial incentives on future vaccination uptake, morals, trust and perceived safety. In a complementary study, we find that informing US residents about the existence of state incentive programmes also has no negative consequences. Our findings inform not only the academic debate on financial incentives for behaviour change but also policy-makers who consider using financial incentives to change behaviour.


"We exploit a randomized controlled trial (RCT) in the context of financial incentives for COVID-19 vaccination (P.C.-M. et al., unpublished, and ref. 5). Participants were offered payments of 200 Swedish krona (SEK; about US $24 at the time) for taking a first dose of a COVID-19 vaccine, which increased first-dose uptake by 4 percentage points 30 days after the trial (uptake remained higher even 3 months later). The RCT setting is ideal in that it allows us to compare individuals who were randomly offered financial incentives for vaccination with individuals who were not offered any financial incentives. We combine the RCT data with new Swedish administrative records for second-dose uptake and with rich, individual-level survey data.

...

"We complement our evidence from Sweden with evidence on the effects of large-scale incentive programmes implemented by US state governments. In a pre-registered study in the USA (n = 3,062), participants randomly assigned to the incentives condition received detailed information about their state’s COVID-19 vaccine incentive programme, whereas participants in the control condition did not receive this information. Because most of the participants were unaware that their state offered incentives for vaccination, this experimental design overcomes the identification problems by creating random variation in perceived exposure to incentives. In line with the evidence from Sweden, we find no negative impacts of being informed about incentive programmes on the willingness of participants to take a further dose"

Saturday, December 17, 2022

Economics of pandemic vaccination in Oxford Review of Economic Policy

Vaccine development and distribution during the Covid pandemic has had some notable successes and some significant shortcomings. 

Here's the latest issue of the Oxford Review of Economic Policy, which has collected articles by economists concerning some of those successes and failures and their lessons for future pandemics.

Volume 38, Issue 4, Winter 2022

Economics of Pandemic Vaccination

ARTICLES

Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 719–741, https://doi.org/10.1093/oxrep/grac036
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 742–770, https://doi.org/10.1093/oxrep/grac037
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 771–796, https://doi.org/10.1093/oxrep/grac026
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 797–817, https://doi.org/10.1093/oxrep/grac029
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 818–832, https://doi.org/10.1093/oxrep/grac028
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 833–850, https://doi.org/10.1093/oxrep/grac032
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 851–875, https://doi.org/10.1093/oxrep/grac035
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 876–886, https://doi.org/10.1093/oxrep/grac031
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 887–911, https://doi.org/10.1093/oxrep/grac033
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 912–923, https://doi.org/10.1093/oxrep/grac027
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 924–940, https://doi.org/10.1093/oxrep/grac034
Oxford Review of Economic Policy, Volume 38, Issue 4, Winter 2022, Pages 941–974, https://doi.org/10.1093/oxrep/grac038