Self-Testing for COVID-19 in São Paulo, Brazil: Results of a Population-Based Values and Attitudes Survey

doi:10.21203/rs.3.rs-1427891/v1

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Research Article

Self-Testing for COVID-19 in São Paulo, Brazil: Results of a Population-Based Values and Attitudes Survey

https://doi.org/10.21203/rs.3.rs-1427891/v1

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Background Brazil is among the countries in South America where the COVID-19 pandemic has hit the general population hardest. Self-testing for SARS-CoV-2 infection is one of the community-based strategies that could help asymptomatic individuals at-risk of COVID-19, as well as those living in areas that are difficult for health personnel to reach, to know their infectious status and contribute to impeding further transmission of the virus.

Methods A population-based survey was conducted in November 2021, to assess the acceptability of rapid SARS-CoV-2 antigen self-testing among the population of São Paulo. Survey respondents were approached at more than 400 different street-points that were randomly selected using a five-stage randomization process. A 35-item structured questionnaire was used. Dependent variables for our analyses were the likelihood to use and willingness to pay for self-testing, and the likelihood of taking preventive measures to prevent onward transmission of COVID-19 following a reactive self-test result. Bivariate and multivariate regression analyses were performed.

Results Overall,417 respondents (44.12% female) participated; 19.66% had previously had COVID-19 disease. A minority (9.59%) felt at high-risk of COVID-19. The majority of both females and males (73.91% and 60.09%, respectively) were in favor of the idea of COVID-19 self-testing. Overall, if self-tests were available, almost half of the sample would be very likely (n = 54, 12.95%) or likely (n = 151, 36.21%) to use one if they felt they needed to. Upon receiving a positive self-test result, the majority of respondents would communicate it (88.49%), request facility-based post-test counseling (98.32%), self-isolate (97.60%), and warn their close contacts (96.64%).

Conclusion Rapid SARS-CoV-2 antigen self-testing could be an acceptable screening tool in São Paulo. The population would be empowered by having access to a technology that would allow them to test, even if asymptomatic, when traveling, or going to work or school. If there is a surge in the incidence of cases,self-testing could be a good approach for mass case detection by Brazil’s already overstretched Unified Health System.

COVID-19

Home diagnostics

Brazil

SARS-CoV-2 testing

Self-testing

Survey

Since the first case of coronavirus disease (COVID-19) caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was reported in Brazil in February 2020 [1], more than 25 million people have been diagnosed with the disease in the country to the end of January 2022 [2]. During the course of the pandemic, it is likely that many SARS-CoV-2-infected Brazilians may have gone undetected due, on one hand, to the absence of COVID-19 symptoms and, on the other hand, to the difficulty in accessing testing via the country’s Unified Health System (SUS, Sistema Único de Saúde) [3, 4]. In Brazil, a country where more than half of its population is aged less than 29 years [5], it is reasonable to assume that a considerable proportion of the population, comprising many young individuals who were asymptomatic carriers of SARS-CoV-2, may not even have suspected they could be transmitting the virus to other individuals [6].

In addition to mass vaccination, which is not progressing without hindrances in Brazil [7], other evidence-based screening strategies are needed to make efficient use of scarce resources for healthcare in this 8.5 million km² territory, to identify cases that, albeit asymptomatic, do play a role in SARS-CoV-2 transmission. A range of community-based screening strategies has been proposed in other contexts, such as self-sampling among travelers [8], routine home screening of school pupils and staff [9], and point-of-care molecular testing at drive-through specimen collection sites [10]. These strategies have relied on the decentralization of SARS-CoV-2 testing. Rapid antigen testing for healthcare professional administration, self-sampling, and rapid antigen detection self-testing devices are among the technologies available to facilitate decentralization, with the aim of making mass screening for COVID-19 cases feasible in resource-constrained settings.

SARS-CoV-2 self-tests are rapid, lateral flow antigen detection assays; they have been regulated for public distribution or for over-the-counter sale in various countries, including Greece [11], Austria [12], the United States [13], and India [14]. These portable assays allow individuals to test themselves in private, at their own convenience, without the intervention of health personnel, and to learn their COVID-19 status in approximately 20 minutes [15]. In essence, SARS-CoV-2 self-tests are very similar to professional rapid antigen tests, albeit the former must be marketed with packaging, test items, and user instructions tailored in such a way that any lay person can self-administer them safely [15–17].

Performance and usability studies of SARS-CoV-2 self-tests have demonstrated their accuracy [17, 18]. Earlier diagnosis, isolation, contact tracing, and access to treatment could be among the potential public health advantages of making SARS-CoV-2 self-testing available to the public [19]. However, acceptability studies are also necessary alongside performance studies, to try to gain an understanding of the public’s perceptions in relation to the value, utility, pertinence, and usability of self-tests. Self-testing for COVID-19 could be widely accepted for COVID-19 screening among symptomatic and asymptomatic end-users in middle-income economies, with areas of the territory that are difficult for healthcare workers to reach. Brazil is not only a vast territory where the provision of medical coverage is challenging but also a society where niche groups of vulnerabilized populations, such as men who have sex with men and transgender persons have expressed the acceptability of self-testing to detect human immunodeficiency virus (HIV) [20, 21] and hepatitis C virus (HCV) [22]. Limited access to conventional facility-based testing due to a lack of finances, remote locations, or the impossibility to forgo daily wages for many of those in the low-income generating sectors are common barriers to testing in Brazil; however, as self-testing for HIV [20, 21, 23] and HCV [22] has to some extent circumvented these barriers, they could also be circumvented by SARS-CoV-2 self-testing.

In January 2022, the Brazil Ministry of Health requested its National Health Surveillance Agency (Anvisa, as per its Portuguese acronym) to approve self-testing for the detection of COVID-19 in Brazil [24]. To ensure SARS-CoV-2 self-testing becomes a game-changer, acceptability studies among end-users are necessary to inform regulatory and diagnostic practice. To tackle this knowledge gap, a population-based survey was conducted in São Paulo with the aim of assessing the population’s values in relation to rapid SARS-CoV-2 antigen self-testing (hereafter referred to as “self-testing”). Specific objectives of the survey were to understand factors that could predict: i) the public’s likelihood to use self-testing, ii) the public’s willingness to pay for a self-testing device, and iii) the likelihood of an individual adhering to health authorities’ recommended actions following a positive self-test result.

Site and population

This population-based survey was conducted during November 2021 in the city of São Paulo, Brazil, a 1521 km² metropolis inhabited by 12.4 million people and capital of a homonymous state. The survey population was São Paulo’s public. Eligibility criteria for all individuals were being aged 18 years or older, willing to provide consent, and free of COVID-19 symptoms at the time they were approached by the surveyors. It was estimated that 392 or more respondents were needed to have a confidence level of 95% that the real value (of willingness to use self-testing) was within ± 5% of the measured value.

Sampling and recruitment

To limit any selection bias, a multi-staged sampling process was used. To begin with, São Paulo’s boundaries were defined using Google MyMaps®, and then the map was divided into 40 areas of similar width. These 40 areas excluded areas that were not possible to enter, such as those belonging to the military. Next, the 40 areas were randomly rearranged using RANDOM.ORG®. From this randomly rearranged list, the first 14 areas were selected as survey areas. Then, to determine the sequence that the surveyors would follow to visit the areas, the 14 areas were randomly rearranged, again using RANDOM.ORG®. Finally, in each area, 30 street-points were randomly selected.

The surveyors were tasked with recruiting one respondent per selected street-point. The survey was conducted over seven days. Upon arrival at each street-point, the surveyors stopped the first passer-by they saw and invited them to participate. If the person declined, the surveyors had to wait three minutes until they could stop a new passer-by, repeating this process until they found a person who was interested in participating.

Data collection and analysis

Informed consent

was obtained and data collection was performed either on-the-spot where privacy could be guaranteed or, if necessary, in a nearby site of the respondent’s choice.

A 35-point questionnaire was used; the questionnaire had been informed by previous FIND-led studies of communities’ values around self-testing for HCV (21). It included items about respondents’ socio-demographics; previous experiences with conventional COVID-19 testing; knowledge of other self-tests; likelihood to use self-testing; willingness to pay for self-testing; barriers to using self-testing; and likely actions upon self-testing positive or negative for SARS-CoV-2 [25]. The questionnaire was designed in English, translated into Portuguese, and pre-piloted in São Paulo among staff in the premises of the survey implementing organization, Instituto Locomotiva. When the questionnaire was considered suitable, it was developed in KoBoToolbox®, re-tested, and deployed in the KoBoCollect® application.

The surveyors collected data from all respondents using their tablet-enabled KoBoCollect® application and submitted the responses immediately. No personal identifiers were collected. Submissions were monitored daily for data inaccuracies or incompleteness. Once the survey ended, all data were exported into an MS-Excel ® file for analysis.

Descriptive statistics and bivariate and multivariate analyses were run in STATA v.14®. The primary outcomes of the analysis were likelihood to use self-testing, willingness to pay for a self-testing device, and likelihood to comply with hygiene and prevention of transmission recommendations upon receipt of a reactive self-test result (i.e., report the result, self-isolate, identify contacts, wear a face mask). Significant associations were sought between the primary outcomes and the respondents’ characteristics, and other aspects of interest to inform future self-testing distribution programs, which were inclusive of but not limited to the perception of risk of COVID-19 disease; awareness of other self-testing devices; and previous experience with conventional COVID-19 testing. Variables that were significantly associated with the primary outcomes at a P-value of < .05 were entered into a multivariate regression model. A logistic regression model was used to identify potential predictors of likelihood to use and willingness to pay for self-testing. Ordinary least squares (OLS) regression was used to identify predictors of compliance with hygiene and prevention of transmission recommendations upon receipt of a reactive self-test result.

Ethics

All respondents gave their informed consent to participate. Respondents signed two copies of the consent document and kept one signed copy. The survey protocol received ethical clearance from the Research Ethics Committee of the Federal University of São Paulo (UNIFESP-CEP).

Participants’ characteristics and experiences with COVID-19

In total, 184 (44.12%) females (mean age 40.1 years (SD 15.53) and 233 (55.87%) males (mean age 45.2 years (SD 15.024) participated (Table 1). Most female participants were in the 18–35 age group (n = 85; 46.20%), while most male participants were in the 36–55 age group (n = 97; 41.63%). All respondents self-identified as Brazilian nationals, with white (branco in Portuguese) (n = 169; 40.63%), brown (pardo) (n = 153; 36.78%), and black (preto) (n = 78; 18.75%) being the most self-reported ethno-racial identities.

Table 1

Respondents’ characteristics and experiences with COVID-19
	Female n = 184 (44.12%)	Male n = 233 (55.87%)	P-value	Total n = 417 (100.00%)
Mean age (SD), years ^A	40.125 (15.553)	45.262 (15.024)	< 0.001	42.995 (15.454)
Age range (years) ^A 18–35 36–55 ≥ 56	85 (46.20) 65 (35.33) 34 (18.48))	69 (29.61) 97 (41.63) 67 (28.76)	< 0.001	154 (36.93) 162 (38.85) 101 (24.22)
Ethno-racial identity ^{A, B} White (Branco) Black (Preto) Brown (Pardo) Indigenous (Indígena) Asian (Amarelo)	74 (17.68) 30 (7.21) 69 (16.58) 10 (2.40) 0 (0.00)	95 (22.83) 48 (11.53) 84 (20.19) 1 (0.24) 1 (0.24)	0.552	169 (40.63) 78 (18.75) 153 (36.78) 11 (2.64) 1 (0.24)
Education ^A None Primary Secondary College/vocational Degree Postgraduate PhD Other	19 (10.33) 42 (22.83) 78 (42.39) 14 (7.61) 25 (13.59) 4 (2.17) 0 (0.00) 2 (1.09)	16 (6.87) 79 (33.91) 109 (46.78) 8 (3.43) 15 (6.44) 0 (0.00) 1 (0.43) 5 (2.15))	0.225	35 (8.39) 121 (29.02) 187 (44.84) 22 (5.28) 40 (9.59) 4 (0.96) 1 (0.24) 7 (1.68)
Employment status ^A Unemployed Student Employed, part-time Employed, full-time Self-employed Retired, on a pension	40 (21.74) 5 (2.72) 6 (3.26) 67 (36.41) 32 (25.00) 20 (10.87)	26 (11.16) 4 (1.72) 3 (1.29) 60 (25.75) 117 (50.22) 23 (9.87)	< 0.001	66 (15.83) 9 (2.16) 9 (2.16) 127 (30.46) 163 (39.09) 43 (10.31)
Feeling at-risk of COVID-19 ^A No risk Low risk Mild risk Moderate risk High risk	11 (5.98) 40 (21.74) 62 (33.70) 49 (26.63) 22 (11.96)	15 (6.44) 59 (25.32) 72 (30.90) 69 (29.61) 18 (7.73)	0.743	26 (6.24) 99 (23.74) 134 (32.13) 118 (28.30) 40 (9.59)
Having had COVID-19 ^A Yes, confirmed by test Yes, confirmed by a healthcare worker	39 (21.20) 5 (2.72)	28 (12.02) 10 (4.29)	0.011	67 (16.07) 15 (3.60)
For those tested... (n, %) Months ago (mean, SD) -- Paid for the test Amount paid (mean USD, SD)	57 (13.66) 9.19 (9) -- 18 (20.22) 3.93 (8.25)	50 (11.99) 77.38 (8) -- 21 (14.48) 2.91 (7.56)	0.016 0.735	107 (25.65) 8.34 (8) -- 39 (16.67) 3.3 (7.83)
^A Percentages took into consideration missing values for each variable, i.e., they were not calculated based on the total sample of 417 respondents ^B In brackets, ethno-racial identity terms used in Brazilian Portuguese

Regarding education, the majority (n = 187; 44.84%) had completed secondary education (Table 1). Completion of primary studies only was higher in males (n = 79; 33.91%) than females (n = 42; 22.83%), whereas completion of university undergraduate and postgraduate degrees was higher among females (n = 29; 15.76%) than males (n = 16; 6.83%). Regarding employment, unemployment was more frequent among females (n = 40; 21.74%) than males (n = 26; 11.16%); employment by a third party was more commonly reported among females (n = 73; 39.67%) than males (n = 63; 27.04%); and self-employment was more common among males (n = 117; 40.22%) than females (n = 32; 25.00%).

Regarding perception of risk of COVID-19, 134 (32.13%) and 118 (28.30%) respondents felt they were at mild- and moderate-risk of COVID-19 disease, respectively (Table 1). In comparison, a minority of respondents (n = 40; 9.59%) felt they were at high-risk of COVID-19. Almost one in four respondents (n = 92; 22.06%) considered that they were sharing a household with elders who were at increased risk of severe COVID-19 disease, although more than half of the sample (n = 232, 55.64%) perceived that they were not living with any individual who was at increased risk of COVID-19. There were 82 (19.66%) respondents who had contracted COVID-19; of these, 67 (16.07%) had their disease confirmed by a professionally-provided test.

Of the sample, 57 (13.66%) females and 50 (11.99%) males reported having ever received a test for COVID-19 (Table 1). Among these respondents, their most recent test was an average of 8.34 (SD 8) months ago. Of these 107 (25.65%) respondents, 18 (4.31%) females and 21 (5.03%) males paid for their most recent test, with a mean cost of 3.93 USD (SD 8.25) and 2.91 USD (SD 7.56), respectively.

Sex at birth was a variable that could statistically explain differences in responses to age, employment and previous access to COVID-19 testing (all P < .05) but not to education, ethno-racial identity, risk perception or paying for their most recent COVID-19 test (Table 1).

Acceptability of COVID-19 self-testing

When asked about their awareness of other self-testing devices, 149 (80.98%) females and 178 (76.39%) males knew about self-tests for pregnancy, while 40 (21.74%) females and 31 (13.30%) males knew about COVID-19 self-testing (Table 2). However, knowledge of other self-testing devices for infectious diseases was limited, with the only other self-tests mentioned by the sample being for HIV (n = 2; 0.48%) and HCV (n = 1; 0.24%).

Table 2

Acceptability of self-testing for COVID-19 disease
	Female n = 184 (44.12%)	Male n = 233 (55.87%)	P-value	Total n = 417 (100.00%)
Awareness of self-testing devices ^A COVID-19 HIV HCV Hypertension Pregnancy Diabetes/Glycaemia	40(21.74) 2 (1.09) 1 (0.54) 14 (7.61) 48 (26.09) 149 (80.98)	31(13.30) 0 (0.00) 0 (0.00) 20 (8.58) 68 (29.18) 178 (76.39)	0.0229	71 (17.03) 2 (0.48) 1 (0.24) 34 (8.15) 116 (27.82) 327 (78.42)
Agreement with the concept of COVID-19 self-test ^A	136(73.91)	140(60.09)	0.003	276 (66.19)
Willingness to pay (n, %) -- Amount, USD (mean, SD)	139 (75.54) -- 5.64 USD (4.35)	150 (64.38) -- 5.63 USD (5.06)	0.014 -- 0.99	289 (69.30) -- 5.64 USD (4.73)
Likelihood of using a self-test ^A Very unlikely Unlikely Neutral Likely Very likely -- Likelihood (mean, SD)	67(36.41) 14(7.61) 11(5.98) 67(36.41) 25(13.59) -- 2.83(1.56)	63(27.04) 37(15.88) 20(8.58) 84(36.05) 29(12.45) -- 2.91(1.45)	0.596	130(31.18) 51(12.23) 31(7.43) 151(36.21) 54(12.95) -- 2.875(1.496)
^A Percentages took into consideration missing values for each variable, i.e., they were not calculated based on the total sample of 417 respondents

Overall, 139 (33.33%) respondents agreed with the idea or concept of people being able to self-test at home for any infectious disease (Table 2). Notably, the rate of agreement doubled when the respondents were asked specifically about their agreement with self-testing for COVID-19, with 73.91% (n = 136) of females and 60.09% (n = 140) of males expressing their agreement. Additionally, if provided free of charge and recommended by health authorities, 44.57% (n = 82) of females and 39.48% (n = 92) of males would be willing to self-test on a weekly basis. Sex at birth was a respondent characteristic that could statistically explain differences in responses to agreement with the concept of COVID-19 self-testing (P < .003).

Likelihood to use self-testing when needed resulted in an overall rating of 2.832/5 (SD 1.557) for females and 2.91/5 (1.449) for males. Overall, if self-tests were available in Brazil, almost half of the sample would be very likely (n = 54, 12.95%) or likely (n = 151, 36.21%) to use them if they felt they needed to. The multivariate model (Fig. 1) showed that those having secondary education (adjusted odds ratio (AOR): 1.75, 95% confidence interval (95%CI): 1.07–2.86, P < .026) or working full-time for an employer (AOR: 1.83, 95%CI: 1.046–3.20, P < .034) had comparatively higher odds of using self-testing; while those who lived in a household with individuals they considered to be at increased risk of severe COVID-19 disease (AOR: 0.467, 95%CI: 0.306–0.71, P < .001) had comparatively lower odds of using self-testing.

If not available free of charge, 289 (69.3%) respondents expressed that they would be willing to pay for self-testing, with a mean of 5.64 USD (SD 4.73) (Table 2). Those respondents aged ≥ 56 years (AOR: 0.482, 95%CI: 0.306–0.71, P < .001) and those self-employed part-time (AOR: 0.394, 95%CI: 0.17–0.91, P < .03) had comparatively lower odds of paying for self-testing (Fig. 2). The respondents with a college degree or higher (AOR: 4.2, 95%CI: 1.6–10.94, P < .003), working full-time (AOR: 2.1, 95%CI: 1.04–4.32, P < .038), who perceived themselves to be at high-risk of COVID-19 (AOR: 1.88, 95%CI: 1.12–3.17, P < .017), and who lived in a household with individuals they considered to be at increased risk of severe COVID-19 disease (AOR: 2.58, 95%CI: 1.52–4.36, P < .001) had comparatively higher odds of paying for self-testing kits (Fig. 2).

Actions upon self-testing for COVID-19

Most respondents stated that, should they perform a self-test and its result were positive, they would go in person to a health facility to request post-test counseling (n = 410, 98.32%), self-isolate (n = 407, 97.60%), identify and warn their close contacts (n = 403, 96.64%), and communicate the result (n = 369, 88.49%) (Table 3). Regarding preferred channels for reporting of results, going in person to a clinic (n = 358, 85.85%) and reporting it directly to community healthcare workers (n = 131, 31.41%) were the preferred means (data not presented). One in ten (n = 42; 10.07%) respondents expressed that they would not report a positive result.

Table 3

Actions taken following a SARS-CoV-2 self-test
	Female n = 184 (44.12%)	Male n = 233 (55.87%)	P-value	Total n = 417 (100.00%)
Practice following receipt of a positive self-test result
Communicate the result to a clinic, hospital and/or COVID hotline ^A	164 (89.13)	205 (87.98)	0.71	369 (88.49)
Go in person to a clinic or hospital to seek post-testing counseling from a healthcare worker ^A	180 (97.83)	230 (98.71)	0.485	410 (98.32)
Self-isolate ^A	180 (97.83)	227 (97.42)	0.79	407 (97.60)
Identify and warn close contacts ^A	178 (96.74)	225 (96.57)	0.92	403 (96.64)
Inform their employer ^A	171 (95.00)	379 (79.45)	0.093	278 (92.98)
Practice following receipt of a negative self-test for a person with symptoms and exposed to a COVID-19 case
Stop self-isolation ^A	164 (89.13)	209 (89.70)	0.76	373 (89.45)
Stop wearing a face mask ^A	22 (11.96)	21 (9.01)	0.21	43 (10.31)
Stop social distancing ^A	58 (31.52)	54 (23.18)	0.16	112 (26.86)
^A Percentages took into consideration missing values for each variable, i.e., they were not calculated based on the total sample of 417 respondents

There was a slight difference in responses regarding communication of a positive result to an employer, with 95.00% (n = 171) of female respondents with an income-generating activity and 79.45% (n = 379) of male respondents with an income-generating activity reporting that they would be willing to report a positive result to their employer (Table 3).

In the event that a respondent knew that they had been exposed to a person who had COVID-19 and that the respondent had COVID-19-related symptoms but received a negative self-test result, the majority of respondents (n = 373, 89,45%) would stop self-isolating (Table 3). However, in this hypothetical scenario, a minority would not stop social distancing (just n = 112, 26.86% would) and would not stop wearing face masks (just n = 43, 10.31% would).

OLS regression found no significant association with any independent variable.

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 [26] or Nigeria [27], 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 [31]. 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 [9], Indonesia [26], Nigeria [27], the United Kingdom [32], and Greece [33], where the study populations also manifested a willingness to use self-testing. Of these studies, only the inquiries in Indonesia [26], Nigeria [27], and Greece [33] targeted the general public. Comparing our survey with that of Goggolidou and colleagues [33], 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 [11]. 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 [34]. 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 [31], 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 [29]), 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.

Rapid SARS-CoV-2 antigen self-testing would be an acceptable solution in São Paulo and possibly most of Brazil for those individuals who suspect that they may be infected with SARS-CoV-2, who want to travel, who want to ensure the safety of themselves and their peers if they go to school or work, or who want to take test because they are a contact of a case. To increase the opportunities for the uptake and good use of self-testing alongside the continuous provision of facility-based, conventional COVID-19 testing for symptomatic individuals and their close contacts, health authorities should regulate to ensure that self-testing is an affordable solution. This should be provided alongside sensitization and awareness-raising, so that people who self-test and receive a positive result can respond with the most appropriate hygiene and preventive measures.

Ethics approval and consent to participate

Ethics approval was obtained from the Research Ethics Committee of the Federal University of São Paulo (UNIFESP-CEP). All informants provided written informed consent. All methods were carried out in accordance with relevant guidelines and regulations.

Data availability

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Consent for publication

Not applicable

Competing interests

The authors have no conflicting or competing interests to declare.

Funding

This work was funded by the Government of Germany. The funders played no role in the study design; in the collection, management, analysis, or interpretation of the data; in writing the report; or in the decision to submit the report for publication

Authors’ contributions

GZMP, EIR, and SS developed the initial research project. MS, HC, JPC adapted the research protocol. MS, HC, JPC led the implementation of the study in Brazil. AD provided leadership of the study implementation.GZMP, AB, DB, performed the data processing and analyses. GZMP and SS wrote the manuscript. All authors have reviewed the final version of the manuscript.

Acknowledgements

We would like to thank all of the informants in São Paulo who contributed to the interviews and focus group discussions.We thank Adam Bodley for editing the manuscript.

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Self-Testing for COVID-19 in São Paulo, Brazil: Results of a Population-Based Values and Attitudes Survey

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Introduction

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Sampling and recruitment

Data collection and analysis

Ethics

Results

Participants’ characteristics and experiences with COVID-19

Acceptability of COVID-19 self-testing

Actions upon self-testing for COVID-19

Discussion

Conclusion

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