Our survey shows that there is potential for the safe use of SARS-CoV-2 self-testing in Brazil. In our inquiry, acceptability was conceptualized as a composite of the public’s values toward self-testing, including agreement with the concept of self-testing (73.91% and 60.09% of female and male respondents were in agreement, respectively); willingness to pay for self-testing (mean of 5.64 USD (SD 4.73) for the 69% of respondents who would pay for a self-test device); willingness to serially self-test (44.57% of females and 39.48% of males expressed a willingness to perform weekly self-tests if they were provided free of charge and recommended by health authorities); and likelihood to use self-testing (12.95% and 36.21% of respondents were “very likely” or “likely”, respectively, to use a self-test when needed). Although satisfactory, the rates of likelihood to use a self-test were not as high as those found in Indonesia  or Nigeria , other countries where surveys of people’s values and attitudes in relation to self-testing have been conducted using the same methodology as used for the survey presented here.
People’s attitudes toward the acceptability of home diagnostics are context-dependent and can be mediated by cost, design, accuracy, accessibility, and societal and authorities’ endorsement of self-testing for infectious diseases, among other factors. Our survey method was designed to assess what the predictors of acceptability might be in a variety of countries. As per our regression analyses, individuals with a secondary education or who are working full-time for an employer might have higher odds of being likely to use a self-testing device when needed, while those living in a household with people they perceive to be at increased risk of severe COVID-19 disease might have lower odds of being likely to using self-testing. The regression analyses also suggested that individuals aged ≥ 56 years and those self-employed part-time may have lower odds of paying for self-testing, while individuals with a college degree or higher, those who are working full-time, those who perceive themselves to be at high-risk of COVID-19, and those living in a household with individuals perceived to be at increased risk of severe COVID-19 disease might have higher odds of paying for a self-test device. The predictors we detected might be helpful for those planning testing services to map the profiles of those who might be more attracted to using (or not using) self-testing and decide who should be targeted via the promotion of self-testing in São Paulo. Nevertheless, we also warrant caution in considering only the predictors detected by our multivariate analyses in future self-testing promotion planning. As suggested by HIV self-testing experiences [20, 21, 23, 28], the more diverse, inclusive, civil society-endorsed, and decentralized a self-testing promotion and distribution program, the more likely it is to meet the needs of different sectors of the public, with full consideration of the intersectionality of their barriers to accessing health with their other personal characteristics.
The drivers for the acceptability of self-testing that this survey explored might be highly dependent on the public’s historical context. Factors that mediate the acceptability of self-testing in Brazil, such as access to facility-based testing and the epidemiological evolution of the pandemic, have undergone frequent changes since February 2020. The drivers of the acceptability of self-testing might increase or decrease depending on how the government’s vaccination and testing programs evolve during 2022. The rapidly changing epidemiological responses since the early part of 2020 are among the reasons why for our survey we considered respondents’ characteristics, and not their context, as predictors of acceptability. Specifically regarding our respondents’ context, as of January 2022, after the survey had already ended, Brazil’s regulatory authorities (i.e., Anvisa) were beginning the process of accepting companies’ requests for approval for distribution of their self-tests throughout the country [24, 29, 30]. As of mid-February 2022, the Anvisa has only approved one device (i.e., the CPMH® COVID-19 antigen self-test) for distribution via private pharmacies and e-commerce in Brazil . Depending on how self-testing is introduced and how it is explained to the population, individuals’ values and preferences for access, usage, and the benefits of self-testing may be impacted. Indeed, the more user-friendly SUS health facilities are to self-testers, the more likely it will be that self-testers react favorably to a reactive result. The more transparent the government is in providing evidence that self-testing can decrease the incidence of COVID-19, the more likely it is that the public, and especially daily laborers, education center attendees, and those interested in traveling or in attending social gatherings, might want to self-test more frequently.
Few studies on the acceptability of self-testing have been published. Of those that have been conducted, our survey findings are aligned with the results of acceptability studies conducted in Germany , Indonesia , Nigeria , the United Kingdom , and Greece , where the study populations also manifested a willingness to use self-testing. Of these studies, only the inquiries in Indonesia , Nigeria , and Greece  targeted the general public. Comparing our survey with that of Goggolidou and colleagues , it should be noted that different contextual factors might have mediated the respondents’ favorable opinions exhibited toward self-testing in each study. In Greece, the health authorities had approved self-testing, distributed self-tests free of charge, and had made educational materials for end-users available via a government website . These efforts could have promoted favorable public opinion toward self-testing. To the best of our knowledge, no such efforts have yet been carried out by São Paulo’s state health authorities.
It can be hypothesized that the public response to the Brazilian government’s behavior with regards to the COVID-19 pandemic in Brazil might have influenced people’s willingness to self-test, especially as our data collection was conducted prior to the surge of the Omicron variant of SARS-CoV-2, which dramatically increased the local (as much as the global) demand for simple, rapid tests for COVID-19. In Brazil, the government’s challenges to providing mass screening and testing have been acknowledged [3, 4]. In mid-January 2022, a phone survey revealed that – in the midst of the Omicron variant wave – more than 8.1 million Brazilians had tried and failed to obtain a COVID-19 test . These challenges to accessing testing have driven many Brazilians to resort to private healthcare. In a previous study of self-testing for HCV, informants reported that they would prefer to either self-test or go to a private practitioner for HCV testing rather than to go to an SUS facility (22). Similarly, now that Anvisa has started receiving requests from manufacturers for the registration of self-tests , many people may opt to purchase a self-test for COVID-19 via a private provider rather than trying to access facility-based testing.
Future studies may provide a more thorough indication of what the reasons might be for the optimum acceptability of self-testing in contexts where these devices have not previously been widely deployed. Future studies will also have to discern what types of attitudes are triggered by the intrinsic advantages of self-testing and which types of attitudes are triggered by health system-related failures to cater for individuals at increased risk of COVID-19. While our survey findings are optimistic (i.e., 88.49%, 97.60%, and 96.64% of respondents would communicate their result, self-isolate, and warn their contacts, respectively), in actuality, post-self-testing behaviors might be different if no social, labor or family support is provided. If social safety nets are not provided, self-isolation and reporting of a COVID-19 infection might be neither feasible nor desirable for affected people. As other self-testing studies in Indonesia and Nigeria have suggested, self-isolation might only be guaranteed if there are provisions in place to ensure that those who use a self-test do not lose their job or social position [26, 27].
Our survey findings have other implications for practice. Ideally, self-tests should cost less than 5.64 USD, to enable people to afford them. Further education on the risk of false-negatives must be provided, as 89.45% of our respondents expressed that they would stop self-isolating if they self-tested negative, even if they were symptomatic and had been in contact with a case. It is possible that an emphasis on frequent testing might be needed, to counterbalance the effects of the likely lower sensitivity of some SARS-CoV-2 self-testing devices (despite the Anvisa requirement that self-tests for distribution in Brazil must have at least 80% sensitivity and 97% specificity ), so that individuals who suspect they might have COVID-19 repeat a self-test every 24 hours and monitor their symptoms before deciding to stop self-isolating.
Considering our findings, it could be argued that self-testing may be a useful case detection tool for the community and contribute to halting or slowing the transmission of SARS-CoV-2. Self-testing has the potential to reduce the burden on health facilities, which should be attending to those who are most seriously ill. It also has the potential to be scaled-up in educational, religious or working environments, where large numbers of individuals regularly congregate and where they could serially self-test. Self-testing could also be useful in the hands of civil society-based grassroots organizations that can promote community-based testing for COVID-19 in underserved favelas or remote areas where communities of indigenous populations are in urgent need of improved access to testing.
It should be noted that this survey had some limitations. First, the findings might be representative of the inhabitants of São Paulo city but not representative of people who live in rural areas of the state. The intention was to conduct the study throughout the entire state, but for logistical reasons and because of restrictions on social movement due to COVID-19, this was not possible. Also, it must be noted that to avoid security incidents within São Paulo city, recruitment in some favelas took place in the areas’ main avenues. It is not possible to know whether the results may have varied slightly if the interiors of these neighborhoods had not been avoided. Despite these impediments, we managed to recruit a diverse sample, with a broad representation of self-expressed ethno-racial identities, education levels and employment statuses.