Predicted impact of banning nonessential, energy-dense food and beverages in schools in Mexico: A microsimulation study.

BACKGROUND: Childhood obesity is a growing concern worldwide. School-based interventions have been proposed as effective means to improve nutritional knowledge and prevent obesity. In 2023, Mexico approved a reform to the General Education Law to strengthen the ban of sales and advertising of nonessential energy-dense food and beverages (NEDFBs) in schools and surroundings. We aimed to predict the expected one-year change in total caloric intake and obesity prevalence by introducing the ban of NEDFBs sales in schools, among school-aged children and adolescents (6 to 17 years old) in Mexico. METHODS AND FINDINGS: We used age-specific equations to predict baseline fat-free mass (FFM) and fat mass (FM) and then estimated total energy intake (TEI) per day. The TEI after the intervention was estimated under 4 scenarios: (1) using national data to inform the intervention effect; (2) varying law compliance; (3) using meta-analytic data to inform the intervention effect size on calories; and (4) using national data to inform the intervention effect by sex and socioeconomic status (SES). We used Hall's microsimulation model to estimate the potential impact on body weight and obesity prevalence of children and adolescents 1 year after implementing the intervention in Mexican schools. We found that children could reduce their daily energy intake by 33 kcal/day/person (uncertainty interval, UI, [25, 42] kcal/day/person), reducing on average 0.8 kg/person (UI [0.6, 1.0] kg/person) and 1.5 percentage points (pp) in obesity (UI [1.1, 1.9] pp) 1 year after implementing the law. We showed that compliance will be key to the success of this intervention: considering a 50% compliance the intervention effect could reduce 0.4 kg/person (UI [0.3, 0.5] kg/person). Our sensitivity analysis showed that the ban could reduce body weight by 1.3 kg/person (UI [0.8, 1.8] kg/person) and up to 5.4 kg/person (UI [3.4, 7.5] kg/person) in the best-case scenario. Study limitations include assuming that obesity and the contribution of NEDFBs consumed at school remain constant over time, assuming full compliance, and not considering the potential effect of banning NEDFBs in stores near schools. CONCLUSIONS: Even in the most conservative scenario, banning sales of NEDFBs in schools is expected to significantly reduce obesity, but achieving high compliance will be key to its success. WHY WAS THIS STUDY DONE?: - School-based interventions have been recognized as effective means to improve nutritional knowledge and prevent obesity-related diseases.- In December 2023, the Chamber of Representatives of Mexico approved an amendment that strengthens and updates the General Education Law (Article 75) and nutritional guidelines to ban the sales and advertising of nonessential energy-dense food and beverages (NEDFBs) in schools. WHAT DID THE RESEARCHERS DO AND FIND?: - We used age-specific equations to predict baseline fat-free mass (FFM) and fat mass (FM) and total energy intake (TEI) per day.- We used microsimulation modeling to predict body weight and obesity prevalence of children and adolescents 1 year after implementing the intervention in Mexican schools.- Our modeling study suggests that an important impact on obesity prevalence can be expected if the law is implemented and enforced as intended. WHAT DO THESE FINDINGS MEAN?: - If successful, this law could serve as an example beyond Mexico on how to achieve changes in body weight through school food regulation.- An important limitation of our main scenario is that we assumed full compliance of schools with the law, yet lower compliance will reduce its impact. We also did not consider historical trends on obesity or NEDFBs consumed in schools during our 1 year simulation, and we considered only the ban impact inside schools, excluding effects near and outside schools.

Binge drinking associated with mean temperature: a cross-sectional study among Mexican adults living in cities.

BACKGROUND: The association between environmental temperature and alcohol consumption has not been widely explored despite the potential that increasing temperatures could promote the consumption of alcoholic beverages and the alcohol-related burden of disease. We aimed to explore the association between temperature and binge drinking in Mexican adults from urban cities, overall, and by alcoholic beverage type. METHODS: Data on 10,552 adults ≥ 18 years was obtained from the 2016 National Survey on Drug, Alcohol, and Tobacco Consumption. The mean annual temperature at the municipality was obtained from the Mexican National Weather Service using monthly temperatures from 2015 to 2016. We analyzed binge drinking for all alcoholic beverages in the last year and by type of alcohol as beer, liquor, wine, and coolers. Associations between mean temperature over the past year and binge drinking over the past year among current drinkers were estimated using multilevel Poisson models with robust standard errors adjusted for age, sex, education level, marital status, and household socioeconomic status, with a fixed effect by region. RESULTS: We observed a non-significant increase in the prevalence of binge drinking for every difference of 1 °C between municipalities of the same region. By alcohol type, a 1 °C increase in mean annual temperature across municipalities of the same region increased the prevalence of beer binge drinking in the past year by 0.9% (PR = 1.009, 95%CI 1.005, 1.013) among beer consumers and the prevalence of coolers' binge drinking by 3.0% (PR = 1.030, 95%CI 1.003, 1.057) in coolers consumers. We observed non-significant results for liquor binge drinking (PR = 1.047, 95%CI 0.994, 1.102) and wine binge drinking (PR = 1.047, 95% 0.944, 1.161). CONCLUSION: People living in municipalities with higher temperatures reported a higher beer binge drinking in Mexican cities. This could account for 196,000 cases of beer binge drinking in 2016. The context of each country needs to be considered when generalizing these findings, and they need to be further explored with longitudinal data as there might be implications for climate change. If our findings are confirmed given the forecasted rising temperatures, we could expect an increase in binge drinking and therefore, in the alcohol burden of disease.

Prevalence of Post-COVID conditions among Mexican COVID-19 survivors: a nationwide cross-sectional study.

BACKGROUND: There are limited population-representative data that describe the potential burden of Post-COVID conditions (PCC) in Mexico. We estimated the prevalence of PCC overall and by sociodemographic characteristics among a representative sample of adults previously diagnosed with COVID-19 in Mexico. We additionally, characterized the PCC symptoms, and estimated the association between diagnosed type-2 diabetes and hypertension with PCC. METHODS: We used data from the 2021 National Health and Nutrition Survey in Mexico, a nationally and regionally representative survey, from August 1st to October 31st, 2021. Using the WHO definition, we estimated the prevalence of PCC by sociodemographics and prevalence of PCC symptoms. We fit multivariable log-binomial regression models to estimate the associations. RESULTS: The prevalence of PCC was 37.0%. The most common persistent symptoms were fatigue (56.8%), myalgia or arthralgia (47.5%), respiratory distress and dyspnea (42.7%), headache (34.0%), and cough (25.7%). The prevalence was higher in older people, women, and individuals with low socioeconomic status. There was no significant association between hypertension and PCC or diabetes and PCC prevalence. CONCLUSIONS: About one-third of the adult Mexican population who had COVID-19 in 2021 had Post-COVID conditions. Our population-based estimates can help assess potential priorities for PCC-related health services, which is critical in light of our weak health system and limited funding.

SARS-CoV-2 seroprevalence and vaccine coverage from August to November 2021: A nationally representative survey in Mexico.

We aimed to estimate self-reported vaccine coverage and SARS-CoV-2 anti-N and anti-S seroprevalence in Mexico overall and for five vaccine types. We used a nationally representative survey with 7236 dried blood spot samples for adults 18 years and older collected from August to November 2021. Anti-N and anti-S seroprevalence were estimated adjusting for the sensitivity and specificity of the immunoassay test. A multivariate Poisson regression model was used to estimate seroprevalence by vaccine type and by age group adjusting for confounders and test performance. Vaccination coverage was 74%, being higher in women compared to men, high socioeconomic status (SES) compared to low and middle SES, graduates compared to people with high school, and formal workers compared to other employment statuses. Anti-N seroprevalence was 59.2%, compared to 84.1% anti-S seroprevalence. Anti-S seroprevalence was higher for vaccinated than unvaccinated participants. All vaccines were associated with more than 70% anti-S seroprevalence, with the lowest being observed for CoronaVac and Ad5-nCoV. Fully vaccinated participants over 60 years presented a lower seroprevalence (77.6%) compared to younger adults (91.1%), with larger differences for ChAdOx1 and CoronaVac vaccines. Between August and November 2021, three out of four Mexican adults had been vaccinated. Vaccination was associated with a higher positivity to anti-S antibodies. While antibodies do not reflect immunity, our results suggest that booster doses should be offered to people over 60 years of age and to adults who received Ad5-nCoV or CoronaVac as primary vaccination schemes.

Prevalence and development of a risk score for oral human papillomavirus infection in men who have sex with men in Mexico.

BACKGROUND: Men who have sex with men (MSM) are at high risk for oral human papillomavirus (HPV infection). There are no specific screening guidelines to facilitate the identification of people at risk for oral HPV infection. We aimed to estimate the prevalence of oral high-risk HPV and create a risk score to identify MSM at higher risk for prevalent oral HPV. METHODS: We collected baseline data from a clinical trial from a subsample of 500 MSM attending sexually transmitted disease treatment clinics; they provided an oral gargle sample for high-risk HPV detection. We calculated oral high-risk HPV prevalence and 95% confidence intervals (CIs), used a logistic regression model to identify factors associated with high-risk HPV infection, and created a risk score. RESULTS: The prevalence of any oral high-risk HPV among MSM was 11.1% (95% CI: 8.6-14.2), with a higher prevalence observed among men living with HIV (14.8%). Factors independently associated with oral high-risk HPV were age ≥40 years (OR = 2.71, 95% CI: 1.28-5.73 compared to <40 years), being HIV-positive with CD4 count 200-499 (OR = 2.76, 95% CI: 1.34-5.65 compared to HIV-negative), and recent recreational use of vasodilators (poppers/sildenafil) (OR = 2.02, 95% CI: 1.02-2.97). The risk score had good discriminatory power (AUC = 0.70, 95% CI: 0.63-0.77). CONCLUSIONS: MSM have specific predictors for prevalent oral high-risk HPV, and a risk score could be used by clinicians to target men with vaccine recommendations and counseling, and identify those who could benefit from primary interventions given the available resources, or for referral to dental services for follow-up when available.

Hepatitis C mortality trends in Mexico from 2001 to 2017.

INTRODUCTION AND OBJECTIVES: We aimed to analyze the trends of total and sex-stratified mortality from hepatitis C virus (HCV) and to estimate the proportion of non-alcoholic liver disease deaths in Mexico attributable to HCV from 2001-2017. MATERIALS AND METHODS: Using the mortality multiple-cause dataset, we selected the codes for acute HCV and chronic HCV to analyze trends from 2001 to 2017. We then estimated the proportion of HCV-related deaths out of non-alcoholic chronic liver disease deaths, by including in the denominator: other acute and chronic viral hepatitis, malignant neoplasm of the liver, liver failure, chronic hepatitis, fibrosis, and cirrhosis of the liver, and other inflammatory diseases of the liver. Average percent change (APC) for trends, overall and by sex, were estimated using Joinpoint regression. RESULTS: The trend in crude mortality rate significantly increased from 2001-2005 (APC 18.4%; 95%CI=12.5, 24.5; p value<0.001), and then significantly decreased from 2013-2017 (APC -6.5%; 95%CI=-10.1, -2.9; p value<0.001). Stratified by sex women experienced a more rapid decline in the 2014-2017 period than men. CONCLUSIONS: HCV mortality seems to have started to decrease, but much remains to be done in terms of prevention, diagnosis, and timely access to treatment.

Barriers, refusal and a hypothetical monetary incentive for Covid-19 vaccination in Mexican adults.

OBJECTIVE: To estimate vaccine uptake and assess sociodemographic conditions associated with vaccination barriers and refusal and to explore the effect of a monetary incentive to overcome them. MATERIALS AND METHODS: We used data from adults from the 2021 National Continuous Health and Nutrition Survey conducted during August-October 2021. We evaluated if an hypothetical monetary incentive between 50-650 MXN (~2.5-31 USD) would overcome barriers or refusal. RESULTS: 73.9% were vaccinated with at least one dose, 7.5% refused, 4.8% reported barriers and 13.8% were ineligible at the time of the survey. Refusal and barriers were more frequent in men, older age, lower education and socioeconomic status, unemployed and informal workers. In people with barriers and refusal, the hypothetical incentive increased the acceptance in 57.6% (95%CI 50.7,64.4%) and 17.4% (95%CI 13.2,21.7%) in people with barriers and refusal, respectively. CONCLUSION: Understanding the reasons for barriers and refusal is crucial for future Covid-19 vaccination campaigns or epidemics. A monetary incentive might increase vaccination uptake, although, cost-effectiveness analyses are needed.

Patrones de consumo de alcohol en adolescentes y adultos mexicanos: Ensanut Continua 2022.

OBJETIVO: Caracterizar los patrones de consumo (actual y excesivo) de alcohol en adolescentes y adultos mexicanos. Material y métodos. Se analizó información de la Encuesta Nacional de Salud y Nutrición Continua 2022 (Ensanut Continua 2022) representativa a nivel nacional y regional. Se estimaron las prevalencias de consumo de alcohol actual y consumo excesivo de alcohol en los últimos 12 meses y 30 días. RESULTADOS: En adolescentes, las prevalencias de consumo actual de alcohol, excesivo en los últimos 12 meses y 30 días fueron de 20.6, 13.9 y 5.2%. En adultos, las prevalencias de consumo actual de alcohol, excesivo en los últimos 12 meses y 30 días fueron 55.5, 40.4 y 19.1%. Las prevalencias fueron mayores en hombres que en mujeres, con diferencias significativas en adultos. En adolescentes, las prevalencias fueron mayores a mayor edad, nivel socioeconómico y en aquellos sin estudios. En adultos, las prevalencias fueron mayores a menor edad, mayor nivel socioeconómico y escolaridad, y en áreas metropolitanas. Conclusión. Estos resultados muestran la necesidad de fortalecer las acciones de implementación, seguimiento y protección ofrecidas por la estrategia SAFER para prevenir y reducir el consumo nocivo de alcohol en adolescentes y adultos.

Prevalencia de prediabetes y diabetes en México: Ensanut 2022.

OBJETIVO: Estimar la prevalencia de prediabetes y diabetes en la población adulta mexicana. Material y métodos. Se utilizó información de la submuestra de adultos de la Encuesta Nacional de Salud y Nutrición 2022 con una muestra de sangre de 10 ml. Se excluyeron 150 individuos con ayuno menor a 8 horas y cuatro personas con diabetes gestacional. La muestra final fue de 1 945 adultos que expande a 78.3 millones de adultos. RESULTADOS: La prevalencia de prediabetes fue de 22.1%, y de diabetes diagnosticada y no diagnosticada de 12.6 y 5.8%, respectivamente, lo que resulta en una prevalencia de diabetes total de 18.3%. Conclusión. La diabetes en México es muy prevalente e implica un reto importante para el sistema de salud. Se requieren acciones contundentes para prevenir la enfermedad, mejorar el tamizaje, el diagnóstico oportuno y el control de la enfermedad.

Prevalencia de anticuerpos y vacunación contra SARS-CoV-2 en 2022 en México.

OBJETIVO: Describir la prevalencia de anticuerpos contra SARS-CoV-2, vacunación, barreras y rechazo a la vacunación Covid-19 en población mexicana. Material y métodos. Se utilizó información de los integrantes del hogar de uno y más años, incluidos en la Encuesta Nacional de Salud y Nutrición Continua 2022 (Ensanut Continua 2022) realizada de agosto-noviembre. Se estimó la prevalencia de anticuerpos antiproteínas N y S de SARS-CoV-2 en muestras de sangre capilar, dosis reportadas de vacunación a Covid-19 y las razones de barreras y rechazo a la vacunación. RESULTADOS: La prevalencia de anticuerpos anti-N fue de 94.4% y de anti-S 98.1%. La prevalencia de anticuerpos anti-S fue mayor en personas vacunadas con una, dos o tres o más dosis que en no vacunadas. Dentro de la población elegible a vacunación, 20.2% no estaba vacunada, 16.2% tenía una dosis, 30% dos dosis y 33.6% tres dosis o más. El 11.2% de la población elegible rechazó la vacunación, 5.5% reportó una barrera y 3.2% reportó que la vacuna no había llegado a su localidad. Conclusión. La prevalencia de anticuerpos por infección natural y por vacunación Covid-19 es alta en México. Las variaciones de rechazo y barreras a la vacunación entre grupos de edad y regiones deben tomarse en cuenta para intensificar esfuerzos específicos para la vacunación.

Hepatitis B infection in Mexican adults: Results of a nationally representative survey.

INTRODUCTION AND OBJECTIVES: Hepatitis B virus (HBV) infection can lead to cirrhosis, hepatocellular carcinoma, and death if untreated. In Mexico, HBV vaccination for all children and adolescents was implemented in 1999. In 2000 the estimated HBV was 0.21% in the population aged 20 years and older. We estimated the national prevalence for hepatitis B surface antigen (HBsAg) and its association with sociodemographic characteristics, including sexual behavior information for those aged 20 to 49 years. MATERIALS AND METHODS: From the 2018 National Health and Nutrition Survey, blood samples were collected from a subsample of 2,280 adults to determine HBsAg. We estimated the national prevalence for HBsAg and evaluated its association with sociodemographic characteristics, adding sexual behavior information for those aged 20 to 49 years. We performed a multiple logistic regression to estimate the association of HBsAg and relevant variables. RESULTS: The 2018 estimated prevalence of HBsAg in the Mexican adult population was 0.51% (95%CI 0.19, 2.33), which represents 411,000 cases. This prevalence was higher than previously estimated and it was higher in women than in men (0.54% versus 0.46%, respectively). We did not find an association between HBsAg and sociodemographic characteristics or sexual behaviors. CONCLUSIONS: Vaccination and screening strategies towards the elimination of viral hepatitis should be reinforced to further reduce the prevalence over the next years.

Acceptance, refusal and hesitancy of Covid-19 vaccination in Mexico: Ensanut 2020 Covid-19.

OBJECTIVE: To estimate the willingness to vaccinate against Covid-19 (acceptance) in the Mexican population and to iden-tify socioeconomic factors associated with vaccine hesitancy and refusal. MATERIALS AND METHODS: We estimated the acceptance, refusal and hesitancy proportions using data from the Covid-19 National Health and Nutrition Survey conducted from August to November 2020. Factors associated with re-fusal and hesitancy were explored using multinomial logistic regression. RESULTS: Covid-19 vaccination acceptance was 62.3%, refusal 28.2% and hesitancy 9.5%. Refusal and hesitancy were associated with being female, having older age, lower educational level, lower socioeconomic status and working in the informal sector. CONCLUSION: National campaigns to incentivize vaccine acceptance need to consider specific subgroups were the likelihood of hesitancy and refusal is high. In Mexico, refusal and hesitancy were higher in vulnerable groups, and people at a higher risk of Covid-19 complica-tions and death.

Who is getting COVID-19 boosters? A latent class analysis in a nationally representative sample of Mexican adults 60 years and over.

OBJECTIVE: Estimate COVID-19 vaccine booster uptake and identify sociodemographic profiles associated with vaccine booster uptake in Mexican adults aged 60 and older. METHODS: Using data from the 2022 National Health and Nutrition Survey, we estimated COVID-19 booster uptake in Mexican adults 60 and older. We conducted a latent class analysis using sociodemographic characteristics and then estimated group-specific booster prevalence. RESULTS: Adults aged 60 and older with a completed vaccination schedule had 80.3% booster coverage. Two groups showed the lowest coverage: 1) unemployed and informal working men with elementary education with low socioeconomic status (73.8% boosted), and 2) female homekeepers with elementary education or less living in rural areas (77.0% boosted). CONCLUSIONS: Our analysis points to the need to reach out to men and women with elementary education or less who live in rural areas to strengthen booster campaigns in the future.

Promoting healthy populations as a pandemic preparedness strategy: a simulation study from Mexico.

Background: The underlying health status of populations was a major determinant of the impact of the COVID-19 pandemic, particularly obesity prevalence. Mexico was one of the most severely affected countries during the COVID-19 pandemic and its obesity prevalence is among the highest in the world. It is unknown by how much the COVID-19 burden could have been reduced if systemic actions had been implemented to reduce excess weight in Mexico before the onset of the pandemic. Methods: Using a dynamic epidemic model based on nationwide data, we compare actual deaths with those under hypothetical scenarios assuming a lower body mass index in the Mexican population, as observed historically. We also model the number of deaths that would have been averted due to earlier implementation of front-of-pack warning labels or due to increases in taxes on sugar-sweetened beverages and non-essential high-energy foods in Mexico. Findings: We estimate that 52.5% (95% prediction interval (PI) 43.2, 61.6%) of COVID-19 deaths were attributable to obesity for adults aged 20-64 and 23.8% (95% PI 18.7, 29.1%) for those aged 65 and over. Had the population BMI distribution remained as it was in 2000, 2006, or 2012, COVID-19 deaths would have been reduced by an expected 20.6% (95% PI 16.9, 24.6%), 9.9% (95% PI 7.3, 12.9%), or 6.9% (95% PI 4.5, 9.5%), respectively. If the food-labelling intervention introduced in 2020 had been introduced in 2018, an expected 6.2% (95% PI 5.2, 7.3%) of COVID-19 deaths would have been averted. If taxes on sugar-sweetened beverages and high-energy foods had been doubled, trebled, or quadrupled in 2018, COVID-19 deaths would have been reduced by an expected 4.1% (95% PI 2.5, 5.7%), 7.9% (95% PI 4.9, 11.0%), or 11.6% (95% PI 7.3, 15.8%), respectively. Interpretation: Public health interventions targeting underlying population health, including non-communicable chronic diseases, is a promising line of action for pandemic preparedness that should be included in all pandemic plans. Funding: This study received funding from Bloomberg Philanthropies, awarded to Juan A. Rivera from the National Institute of Public Health; Community Jameel, the UK Medical Research Council (MRC), Kenneth C Griffin, and the World Health Organization.

Nationally representative SARS-CoV-2 antibody prevalence estimates after the first epidemic wave in Mexico.

Seroprevalence surveys provide estimates of the extent of SARS-CoV-2 infections in the population, regardless of disease severity and test availability. In Mexico in 2020, COVID-19 cases reached a maximum in July and December. We aimed to estimate the national and regional seroprevalence of SARS-CoV-2 antibodies across demographic and socioeconomic groups in Mexico after the first wave, from August to November 2020. We used nationally representative survey data including 9,640 blood samples. Seroprevalence was estimated by socioeconomic and demographic characteristics, adjusting by the sensitivity and specificity of the immunoassay test. The national seroprevalence of SARS-CoV-2 antibodies was 24.9% (95%CI 22.2, 26.7), being lower for adults 60 years and older. We found higher seroprevalence among urban and metropolitan areas, low socioeconomic status, low education and workers. Among seropositive people, 67.3% were asymptomatic. Social distancing, lockdown measures and vaccination programs need to consider that vulnerable groups are more exposed to the virus and unable to comply with lockdown measures.

SARS-CoV-2 infection fatality rate after the first epidemic wave in Mexico.

BACKGROUND: Estimates of SARS-CoV-2 infection fatality rates (IFRs) in developing countries remain poorly characterized. Mexico has one of the highest reported COVID-19 case-fatality rates worldwide, although available estimates do not consider serologic assessment of prior exposure nor all SARS-CoV-2-related deaths. We aimed to estimate sex- and age-specific IFRs for SARS-CoV-2 in Mexico. METHODS: The total number of people in Mexico with evidence of prior SARS-CoV-2 infection was derived from National Survey of Health and Nutrition-COVID-19 (ENSANUT 2020 Covid-19)-a nationally representative serosurvey conducted from August to November 2020. COVID-19 mortality data matched to ENSANUT's dates were retrieved from the death-certificate registry, which captures the majority of COVID-19 deaths in Mexico, and from the national surveillance system, which covers the subset of COVID-19 deaths that were identified by the health system and were confirmed through a positive polymerase chain reaction test. We analysed differences in IFRs by urbanization and region. RESULTS: The national SARS-CoV-2 IFR was 0.47% (95% CI 0.44, 0.50) using death certificates and 0.30% (95% CI 0.28, 0.33) using surveillance-based deaths. The IFR increased with age, being close to zero at age <30 years, but increasing to 1% at ages 50-59 years in men and 60-69 years in women, and being the highest at ≥80 years for men (5.88%) and women (6.23%). Across Mexico's nine regions, Mexico City (0.99%) had the highest and the Peninsula (0.26%) the lowest certificate-based IFRs. Metropolitan areas had higher certificate-based IFR (0.63%) than rural areas (0.17%). CONCLUSION: After the first wave of the COVID-19 pandemic, the overall IFR in Mexico was comparable with those of European countries. The IFR in Mexico increased with age and was higher in men than in women. The variations in IFRs across regions and places of residence within the country suggest that structural factors related to population characteristics, pandemic containment and healthcare capabilities could have influenced lethality at the local level.

Prevalence of hepatitis C in the adult Mexican population: National Survey of Health and Nutrition 2018.

Background: Hepatitis C is a preventable and treatable disease that has been declared a public health problem. In 2012, the prevalence of HCV serum anti-bodies in the Mexican adult population aged 20 to 49 years was 0·30%. Methods: We randomly selected a probabilistic sub-sample of 12,389 adults (20+ years) from adults participating in the National Health and Nutrition Survey (ENSANUT) 2018 who provided a venous blood sample. Anti-HCV antibodies and HCV RNA were determined for this sub-sample. We estimated the national prevalence of anti-HCV antibodies and the proportion with viral RNA detection and evaluated their association with sociodemographic characteristics for all adults and with sexual behaviours in those aged 20 to 49 years using logistic regression. Findings: The national prevalence of anti-HCV antibodies in serum was 0·38% (95%CI 0·24, 0·59) in the population aged 20 years and older; 14·9% of them had viral RNA. In the population aged 20 to 49 years antibody prevalence was 0·23% (95%CI 0·11, 0·48), being higher for males and people living in urban areas. In the population aged 50 years and older, the prevalence was 0·59% (95%CI 0·34, 1·06). Interpretation: The prevalence of antibodies anti-HCV in people aged 20 to 49 years was similar in 2018 than in 2012, suggesting that the prevalence of HCV has remained stable. ENSANUT is a household study and could underestimate the prevalence of HCV. Further efforts must be made to identify cases in non-household populations. Funding: National Institute of Statistics and Geography and National Institute of Public Health of Mexico [CIEE/1807].

Comparable diagnostic accuracy of SARS-CoV-2 Spike RBD and N-specific IgG tests to determine pre-vaccination nation-wide baseline seroprevalence in Mexico.

A major challenge for developing countries during the COVID-19 pandemic is affordable and adequate monitoring of disease progression and population exposure as the primary source relevant epidemiological indicators. Serology testing enables assessing population exposure and to guide vaccination strategies but requires rigorous accuracy validation before population-wide implementation. We adapted a two-step ELISA protocol as a single-step protocol for detection of IgG against the Receptor Binding Domain (RBD) of SARS-CoV-2 spike protein and compared its diagnostic accuracy with a commercial immunoassay anti-nucleoprotein IgG. Both methods yielded adequate and comparable diagnostic accuracy after 3 weeks post-symptom onset and were implemented in a nation-wide population based serological survey during August-November 2020. Anti-RBD National seroprevalence was 23.6%, 1.3% lower, but not significantly, than for anti-N. Double positive seroprevalence was 19.7%. Anti-N single-positive seroprevalence was 3.72% and anti-RBD single-positive seroprevalence was 1.98%. Discrepancies in the positivity to either single marker may be due to different kinetics of each antibody marker as well as the heterogeneity of the sampling time in regards to local epidemic waves. Baseline single positivity prevalence will be useful to assess the serological impact of vaccination and natural infection in further serosurveillance efforts.

Reduction of HPV16/18 prevalence in young women after eight years of three- and two-dose vaccination schemes.

BACKGROUND: Recommendations for human papillomavirus vaccination have relied on immunogenicity studies and efficacy results derived from adult women. Insufficient information exists regarding HPV effectiveness in vaccinated girls as they become sexually active, regardless of dose scheme. We aimed to compare the prevalence of high-risk HPV between unvaccinated and vaccinated young women eight years after immunization. METHODS: After eight years, we recontacted women who received two-dose of bivalent or three-dose-either bivalent or quadrivalent-, HPV vaccine when aged 9-10 years-old as part of a clinical trial. Additionally, we recruited a contemporaneous unvaccinated woman group for comparison. Only those sexually active were included. High-risk HPV DNA was determined in urine samples and compared across groups. RESULTS: The prevalence of HPV16/18 types was 6.8% (95 %CI 3.2-14.1%) in the unvaccinated (n = 6/88), 1.1% (95 %CI 0.2-5.8%) in the three-dose (n = 1/93), and 0.0% (95 %CI 0.0-7.0%) in the two-dose group (n = 0/51). CONCLUSION: HPV vaccination, with two-dose of bivalent or three-dose schemes-either with the bivalent or quadrivalent vaccine-, was associated with a lower prevalence of HPV16/18 types eight years after primary immunization.