Risk Compensation and COVID-19 Vaccines.
02 Mar 2021-Annals of Internal Medicine (American College of Physicians)-Vol. 174, Iss: 6, pp 858-859
TL;DR: In this paper, the authors discuss the Peltzman effect, a phenomenon in which individuals respond to safety measures with a compensatory increase in risky behavior, and how it relates to the COVID-19 pandemic through "pandemic fatigue" and post vaccination behavior.
Abstract: The authors of this commentary discuss the “Peltzman Effect,” a phenomenon in which individuals respond to safety measures with a compensatory increase in risky behavior, and how it relates to the COVID-19 pandemic through “pandemic fatigue” and postvaccination behavior.
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TL;DR: In this article, estimates of vaccine effectiveness are urgently needed to support mass vaccination campaigns to prevent coronavirus disease 2019 (Covid-19) are occurring in many countries.
Abstract: Background Mass vaccination campaigns to prevent coronavirus disease 2019 (Covid-19) are occurring in many countries; estimates of vaccine effectiveness are urgently needed to support deci...
572 citations
TL;DR: The authors of this cohort study analyzed vaccination, surveillance, screening, tracing, and quarantine data to determine the effectiveness of inactivated COVID-19 vaccines against infections, pneumonia, and severe or critical illness caused by the Delta variant.
Abstract: Real-world evidence on inactivated COVID-19 vaccines against the SARS-CoV-2 B.1.617.2 (Delta) variant is limited. The authors of this cohort study analyzed vaccination, surveillance, screening, tracing, and quarantine data to determine the effectiveness of inactivated COVID-19 vaccines against infections, pneumonia, and severe or critical illness caused by the Delta variant.
48 citations
TL;DR: Wang et al. as discussed by the authors estimated inactivated vaccine effectiveness against the B.1.2 (Delta) variant of SARS-CoV-2, leaving an important gap in the evidence base about inactivated COVID-19 vaccines for use by immunization programs.
Abstract: Real-world evidence on inactivated COVID-19 vaccines against the highly transmissible B.1.617.2 (Delta) variant of SARS-CoV-2 is limited, leaving an important gap in the evidence base about inactivated COVID-19 vaccines for use by immunization programs.To estimate inactivated vaccine effectiveness (VE) against the B.1.617.2 variant.Retrospective cohort study.The study was based on the first outbreak of the B.1.617.2 variant in mainland China that was discovered and traced in Guangdong in May and June 2021.10 805 adult case patients with laboratory-confirmed infection and close contacts.Participants were categorized as unvaccinated, partially vaccinated (1 dose), and fully vaccinated (2 doses). We estimated VE against the primary outcome of pneumonia and the secondary outcomes of infections, symptomatic infections, and severe or critical illness associated with the B.1.617.2 variant.Results are reported in the order of outcome severity. Of 10 805 participants, 1.3% contracted infections, 1.2% developed symptomatic infections, 1.1% had pneumonia, and 0.2% had severe or critical illness. The adjusted VEs of full vaccination were 51.8% (95% CI, 20.3% to 83.2%) against infection, 60.4% (CI, 31.8% to 88.9%) against symptomatic infection, and 78.4% (CI, 56.9% to 99.9%) against pneumonia. Also, full vaccination was 100% (CI, 98.4% to 100.0%) effective against severe or critical illness. By contrast, the adjusted VEs of partial vaccination against infection, symptomatic infection, and pneumonia were 10.7% (CI, -41.2% to 62.6%), 6.8% (CI, -47.4% to 61.0%), and 11.6% (CI, -42.6% to 65.8%), respectively.Observational study with possible unmeasured confounders; insufficient data to do reliable subgroup analyses by age and vaccine brand.Full vaccination with inactivated vaccines is effective against the B.1.617.2 variant. Effort should be made to ensure full vaccination of target populations.National Natural Science Foundation of China and Key-Area Research and Development Program of Guangdong Province.
46 citations
TL;DR: In this article, the authors used monthly panel data from October 2020 to March 2021 in the UK COVID-19 Social Study to assess changes in compliance following vaccination, measuring compliance with two items on compliance with guidelines in general and compliance with social distancing.
Abstract: INTRODUCTION: COVID-19 vaccines do not confer immediate immunity and vaccinated individuals may still be at risk of transmitting the virus. Governments have not exempted vaccinated individuals from behavioural measures to reduce the spread of COVID-19, such as practising social distancing. However, vaccinated individuals may have reduced compliance with these measures, given lower perceived risks. METHODS: We used monthly panel data from October 2020 to March 2021 in the UK COVID-19 Social Study to assess changes in compliance following vaccination. Compliance was measured with two items on compliance with guidelines in general and compliance with social distancing. We used matching to create comparable groups of individuals by month of vaccination (January, February or not vaccinated by February) and fixed effects regression to estimate changes in compliance over the study period. RESULTS: Compliance increased between October 2020 and March 2021, regardless of vaccination status or month of vaccination. There was no clear evidence that vaccinated individuals decreased compliance relative to those who were not yet vaccinated. CONCLUSION: There was little evidence that sample members vaccinated in January or February reduced compliance after receiving vaccination for COVID-19. Continued monitoring is required as younger individuals receive the vaccine, lockdown restrictions are lifted and individuals receive second doses of the vaccine.
27 citations
08 Apr 2021
TL;DR: The vaccine hesitancy may become a defining theme of the next stage of the COVID-19 pandemic as discussed by the authors, as supply meets demand, vaccine shortage becomes a major concern.
Abstract: Vaccines are one of the greatest medical innovations of all time, but there has been skepticism about them throughout history. Although initial concerns about scarcity increased public demand for COVID-19 vaccines, as supply meets demand, vaccine hesitancy may become a defining theme of the next stage of the COVID-19 pandemic.
27 citations
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TL;DR: In this paper, a comprehensive post-efficacy strategy for the next steps to ensure vaccination of the global population is now required, including how to manufacture billions of doses of high-quality vaccines, support for vaccine purchase, coordination of supply, equitable distribution of vaccines and the logistics of global vaccine delivery, all of which are a prelude to a massive vaccination campaign targeting people of all ages.
Abstract: After the recent announcement of COVID-19 vaccine efficacy in clinical trials by several manufacturers for protection against severe disease, a comprehensive post-efficacy strategy for the next steps to ensure vaccination of the global population is now required. These considerations should include how to manufacture billions of doses of high-quality vaccines, support for vaccine purchase, coordination of supply, the equitable distribution of vaccines and the logistics of global vaccine delivery, all of which are a prelude to a massive vaccination campaign targeting people of all ages. Furthermore, additional scientific questions about the vaccines remain that should be answered to improve vaccine efficacy, including questions regarding the optimization of vaccination regimens, booster doses, the correlates of protection, vaccine effectiveness, safety and enhanced surveillance. The timely and coordinated execution of these post-efficacy tasks will bring the pandemic to an effective, and efficient, close.
410 citations
TL;DR: This paper surveys risk compensation by reviewing its history, discussing its theoretical foundations, outlining evidence for and against its claims, and providing the author's own views.
Abstract: Editors comment: We are proud to be able to bring to our readers this full text version of the Haddon Memorial Lecture delivered at the recent Fifth World Conference on Injury Prevention and Control in New Delhi, India. James Hedlund offers a brilliant review of one of the most important areas of debate in the entire field of injury control. This is the most complete, most perceptive, and well balanced appraisals of this complex issue I have ever read. Take the time to digest it completely. Our thanks to the Insurance Institute for Highway Safety for agreeing to permit us to publish it.
Government regulations and industry practices constrain our behavior in many ways in an attempt to reduce injuries. Safety features are designed into products we use: cars now have airbags; medicine bottles have “childproof” caps. Laws require us to act in a safe manner: we must wear seat belts while driving and hard hats in construction areas. But do these measures influence our behavior in other ways? Risk compensation theory hypothesizes that they do, that we “use up” the additional safety though more risky actions.
This paper surveys risk compensation by reviewing its history, discussing its theoretical foundations, outlining evidence for and against its claims, and providing the author's own views. It concludes by discussing the relevance of risk compensation for injury prevention workers who seek to reduce unintentional injuries.
Injury prevention as a discipline began when injuries were understood to be both predictable and preventable. Most injuries are the unintended consequences of individual actions in a risky environment; they are not due to fate or to problem behavior. This understanding led to three fundamental injury prevention strategies, as described in the comprehensive report Injury in America 1:
290 citations
TL;DR: These data provide support for both behavioral disinhibition and risk compensation models and underscore the importance of developing behavioral interventions to accompany any wide-scale provision of PREP to high-risk populations.
Abstract: Objectives: Preexposure prophylaxis (PREP) is an emerging HIV prevention strategy; however, many fear it may lead to neglect of traditional risk reduction practices through behavioral disinhibition or risk compensation. Methods: Participants were 180 HIV-negative high-risk men who have sex with men recruited in New York City, who completed an Audio Computer Assisted Self Interview-administered survey between September 2007 and July 2009. Bivariate and multivariate logistic regression models were used to predict intention to use PREP and perceptions that PREP would decrease condom use. Results: Almost 70% (n = 124) of participants reported that they would be likely to use PREP if it were at least 80% effective in preventing HIV Of those who would use PREP, over 35% reported that they would be likely to decrease condom use while on PREP. In multivariate analyses, arousal/pleasure barriers to condom use significantly predicted likelihood of PREP use (odds ratio = 1.71, P < 0.05) and risk perception motivations for condom use significantly predicted decreased condom use on PREP (odds ratio = 2.48, P < 0.05). Discussion: These data provide support for both behavioral disinhibition and risk compensation models and underscore the importance of developing behavioral interventions to accompany any wide-scale provision of PREP to high-risk populations.
252 citations
TL;DR: Among gay and bisexual men using PrEP, STIs were highly concentrated among a subset, and receipt of PrEP after study enrollment was associated with an increased incidence of STIs compared with preenrollment, highlighting the importance of frequent STI testing.
Abstract: Importance Emerging evidence suggests that risk of bacterial sexually transmitted infections (STIs) increases among gay and bisexual men following initiation of HIV preexposure prophylaxis (PrEP). Objective To describe STI incidence and behavioral risk factors among a cohort of predominantly gay and bisexual men who use PrEP, and to explore changes in STI incidence following PrEP commencement. Design, Setting, and Participants The Pre-exposure Prophylaxis Expanded (PrEPX) Study, a multisite, open-label intervention study, was nested within the Australian Collaboration for Coordinated Enhanced Sentinel Surveillance (ACCESS) clinic network. A total of 4275 participants were enrolled (July 26, 2016–April 1, 2018) in Victoria, Australia. Of these, 2981 enrolled at 5 ACCESS clinics (3 primary care, 1 sexual health, and 1 community-based HIV rapid testing service), had at least 1 follow-up visit, and were monitored until April 30, 2018. Exposures Upon enrollment, participants received daily oral tenofovir disoproxil fumurate and emtricitabine for HIV PrEP, quarterly HIV and STI testing, and clinical monitoring. Main Outcomes and Measures The primary outcome was incidence of chlamydia, gonorrhea, or syphilis. Incidence rates and hazard ratios describing behavioral risk factors of STI diagnosis were calculated. Incidence rate ratios (IRRs), adjusted for change in testing frequency, described changes in STI incidence from 1-year preenrollment to study follow-up among participants with preenrollment testing data (n = 1378). Results Among the 2981 individuals (median age, 34 years [interquartile range, 28-42]), 98.5% identified as gay or bisexual males, 29% used PrEP prior to enrollment, 89 (3%) withdrew and were censored at date of withdrawal, leaving 2892 (97.0%) enrolled at final follow-up. During a mean follow-up of 1.1 years (3185.0 person-years), 2928 STIs were diagnosed among 1427 (48%) participants (1434 chlamydia, 1242 gonorrhea, 252 syphilis). STI incidence was 91.9 per 100 person-years, with 736 participants (25%) accounting for 2237 (76%) of all STIs. Among 2058 participants with complete data for multivariable analysis, younger age, greater partner number, and group sex were associated with greater STI risk, but condom use was not. Among 1378 participants with preenrollment testing data, STI incidence increased from 69.5 per 100 person-years prior to enrollment to 98.4 per 100 person-years during follow-up (IRR, 1.41 [95% CI, 1.29-1.56]). After adjusting for testing frequency, the increase in incidence from 1 year preenrollment to follow-up was significant for any STI (adjusted IRR, 1.12 [95% CI, 1.02-1.23]) and for chlamydia (adjusted IRR, 1.17 [95% CI, 1.04-1.33]). Conclusions and Relevance Among gay and bisexual men using PrEP, STIs were highly concentrated among a subset, and receipt of PrEP after study enrollment was associated with an increased incidence of STIs compared with preenrollment. These findings highlight the importance of frequent STI testing among gay and bisexual men using PrEP.
235 citations
TL;DR: None of the studies of sexual behaviors and/or biological outcomes found evidence of riskier behaviors or higher rates of STIs after HPV vaccination, which should be reassuring to parents and health care providers.
Abstract: There has been some concern among parents and in the media that vaccinating children against human papillomavirus could be seen as giving children permission to engage in risky sexual behaviors (also known as sexual disinhibition). Several studies have found this concern to be unfounded but there have been no attempts to synthesize the relevant studies in order to assess if there is evidence of sexual disinhibition. The aim of this study was to synthesize recent literature examining sexual behaviors and biological outcomes (e.g., sexually transmitted infections) post-HPV vaccination. We reviewed literature from January 1, 2008-June 30, 2015 using PubMed, CINAHL, and Embase with the following search terms: [(sex behavior OR sex behavior OR sexual) AND (human papillomavirus OR HPV) AND (vaccines OR vaccine OR vaccination)] followed by a cited reference search. We included studies that examined biological outcomes and reported behaviors post-vaccination in both males and females. Studies were reviewed by title and abstract and relevant studies were examined as full-text articles. We identified 2,503 articles and 20 were eventually included in the review. None of the studies of sexual behaviors and/or biological outcomes found evidence of riskier behaviors or higher rates of STIs after HPV vaccination. Instead, the studies found that vaccinated compared to unvaccinated individuals were less likely to report vaginal intercourse without a condom (OR = 0.5; 95%CI = 0.4-0.6) and non-use of contraception (OR = 0.27; 95%CI = 0.15-0.48) and unvaccinated participants had higher rates of Chlamydia (OR = 2.3; 95%CI = 1.06-5.00). These results should be reassuring to parents and health care providers.
76 citations