Seroprevalence and SARS-CoV-2 antibodies distribution in Portugal following mass vaccination campaign

Introduction

Information on post-infection and vaccine-induced SARS-CoV-2 seroprevalence is important for public health policies. A 3rd wave of National Serological Survey (ISN3COVID-19) was conducted to measure SARS-CoV-2 seroprevalence and characterize specific antibodies distribution in Portuguese population in September - November 2021, following a mass vaccination campaign.

Methods

ISN3COVID-19 was a cross-sectional epidemiological study that collected serum samples and questionnaire data on a sample of Portuguese residents aged 1 year or older (n = 4545). SARS-CoV-2 IgG anti-nucleoprotein and anti-spike antibody levels were measured using Abbott Chemiluminescent Microparticle Immunoassays. Seroprevalence was estimated for the overall sample and stratified by age group, sex, region and self-reported chronic conditions. Medians and respective 95% confidence intervals (95%CI) were used to describe the distribution of SARS-CoV-2 antibodies in specific population subgroups.

Results

The overall seroprevalence of SARS-CoV-2 (post-infection or vaccine-induced) was 86.4% (95%CI: 85.2 to 87.6%), post-infection seroprevalence was 7.5% (95%CI: 6.6 to 8.5). Higher seroprevalence was observed among 50-59 years-old (96.5%), women (88.3%), and those with two or more self-reported chronic conditions (90.8%). Higher IgG (anti-Spike) levels were estimated for individuals vaccinated with the booster dose (median=12601.3 AU/ml; 95%CI: 4127.5 to 19089.1) and for those vaccinated with two doses of Spikevax® vaccine (median=7012.7 AU/ml, 95%CI: 5568.8 to 8456.6).

Conclusions

The SARS-CoV-2 seroprevalence was high and consistent with vaccine coverage in Portugal. Seropositivity was associated with sex, age and previous chronic conditions. The anti-SARS-CoV-2 anti-spike IgG levels varied according to vaccine brand and number of doses. These results show that monitoring seroprevalence and SARS-CoV-2 antibody distribution is of paramount importance to guide public health policies.

Key messages

• Significant increase in SARS-CoV-2 seroprevalence following the mass vaccination campaign consistent with the high vaccine coverage achieved in Portugal.

• Continuous monitoring of the population‐level IgG response after vaccination remains important to guide further public health measures.

Ambient particulate matter exposure interacts with abdominal obesity to increase blood triglycerides

Background

Blood lipids levels dysregulation represent potential mechanism intermediating the adverse cardiovascular effects of ambient particulate matter (PM) exposure. The present study aims to estimate the effect of particulate matter (PM10) exposure on blood lipid levels (TC, Total Cholesterol; HDL-C, High-Density Lipoprotein Cholesterol; LDL-C, Low-Density Lipoprotein Cholesterol; TG, Triglycerides) in the adult Portuguese mainland population and to assess the potential mediation and/or modification action of abdominal obesity on this effect.

Methods

We used data from 2390 participants of the 1st Portuguese Health Examination Survey (INSEF, 2015) with available data on blood lipids parameters and living within a 30km radius of an air quality monitoring station with available PM10 measurements. PM10 concentrations were acquired from the air quality monitoring network of the Portuguese Environment Agency. Generalized linear models were used to assess the effect of 1-year PM10 exposure on blood lipids values. An interaction term was introduced in the models to test the modification action of abdominal obesity.

Results

We found an association between long-term exposure to PM10 and non-fasting blood TG levels after adjustment for age, sex, education, occupation, lifestyles related variables and temperature but only in participants with abdominal obesity (1.84% TG increase per each 1 µg/m3 PM10 increment, 95% CI: 0.02%; 3.69%) which is well supported by the sensitivity analysis.

Conclusions

Our study demonstrate that even at low levels of exposure, long-term PM10 exposure interacts with abdominal obesity to increase blood TG levels. To the best of our knowledge, this is the first study showing the modification action of abdominal obesity regarding the PM10 effect on a blood lipid parameter. Our findings suggest that reducing both abdominal obesity prevalence and PM10 below current standards would result in additional health benefits for the population.

Key messages

Long-term PM10 exposure interacts with abdominal obesity to increase non-fasting blood triglycerides levels by about 2% per each 1 µg/m3 PM10 increase. Reducing both abdominal obesity prevalence and PM10 below current standards would result in additional health benefits for the population.