Serum and Salivary IgG and IgA Response After COVID-19 Messenger RNA Vaccination.

Importance: There is still considerable controversy in the literature regarding the capacity of intramuscular messenger RNA (mRNA) vaccination to induce a mucosal immune response. Objective: To compare serum and salivary IgG and IgA levels among mRNA-vaccinated individuals with or without previous SARS-CoV-2 infection. Design, Setting, and Participants: In this cohort study, SARS-CoV-2-naive participants and those with previous infection were consecutively included in the CoviCompare P and CoviCompare M mRNA vaccination trials and followed up to day 180 after vaccination with either the BNT162b2 (Pfizer-BioNTech) vaccine or the mRNA-1273 (Moderna) vaccine at the beginning of the COVID-19 vaccination campaign (from February 19 to June 8, 2021) in France. Data were analyzed from October 25, 2022, to July 13, 2023. Main Outcomes and Measures: An ultrasensitive digital enzyme-linked immunosorbent assay was used for the comparison of SARS-CoV-2 spike-specific serum and salivary IgG and IgA levels. Spike-specific secretory IgA level was also quantified at selected times. Results: A total of 427 individuals were included in 3 groups: participants with SARS-CoV-2 prior to vaccination who received 1 single dose of BNT162b2 (Pfizer-BioNTech) (n = 120) and SARS-CoV-2-naive individuals who received 2 doses of mRNA-1273 (Moderna) (n = 172) or 2 doses of BNT162b2 (Pfizer-BioNTech) (n = 135). The median age was 68 (IQR, 39-75) years, and 228 (53.4%) were men. SARS-CoV-2 spike-specific IgG saliva levels increased after 1 or 2 vaccine injections in individuals with previous infection and SARS-CoV-2-naive individuals. After vaccination, SARS-CoV-2-specific saliva IgA levels, normalized with respect to total IgA levels, were significantly higher in participants with previous infection, as compared with the most responsive mRNA-1273 (Moderna) recipients (median normalized levels, 155 × 10-5 vs 37 × 10-5 at day 29; 107 × 10-5 vs 54 × 10-5 at day 57; and 104 × 10-5 vs 70 × 10-5 at day 180 [P < .001]). In contrast, compared with day 1, spike-specific IgA levels in the BNT162b2-vaccinated SARS-CoV-2-naive group increased only at day 57 (36 × 10-5 vs 49 × 10-5 [P = .01]). Bona fide multimeric secretory IgA levels were significantly higher in individuals with previous infection compared with SARS-CoV-2-naive individuals after 2 antigenic stimulations (median optical density, 0.36 [IQR, 0.16-0.63] vs 0.16 [IQR, 0.10-0.22]; P < .001). Conclusions and Relevance: The findings of this cohort study suggest that mRNA vaccination was associated with mucosal immunity in individuals without prior SARS-CoV-2 infection, but at much lower levels than in previously infected individuals. Further studies are needed to determine the association between specific saliva IgA levels and prevention of infection or transmission.

Exploring cell-free assays for COVID-19 serosurvey.

Serosurveys to monitor immunity toward COVID-19 in the population are primarily performed using an ELISA to screen samples for SARS-CoV-2 antibodies, followed by confirmation by a virus neutralization test, which is considered the Gold Standard. However, virus neutralization test may not be feasible for some laboratories because of the requirement for specific facilities and trained personnel. In an attempt to address this limitation, we evaluated three cell-free methods as potential alternatives for assessing SARS-CoV-2 seroprevalence in human population from plasma. We report the establishment of two inhibition ELISAs designed to detect anti-Spike RBD IgG antibodies and a microsphere quantitative suspension array technology assay, based on the Luminex xMAP platform, to measure the presence of antibodies against various SARS-CoV-2 antigens, including anti-RBD. These methods were also compared to a commercial chemiluminescent immunoassay designed for anti-RBD antibodies detection and to the combined ELISA + virus neutralization test strategy. These cell-free assays performed equally to estimate the percentage of positive and negative samples and could be used to determine the prevalence of SARS-CoV-2 antibodies in human population, at least in cohort with high-expected prevalence, without the use of seroneutralization assay.

Incidence of COVID-19 mRNA vaccine symptomatic breakthrough infections during Omicron circulation in adults with or without infection prior to vaccination.

OBJECTIVES: COVID-19 vaccine breakthrough infections were frequently reported during circulation of the Omicron variant. The ANRS|MIE CoviCompareP study investigated these infections in adults vaccinated and boosted with BNT162b2 [Pfizer-BioNTech] and with/without SARS-CoV-2 infection before vaccination. METHODS: In the first half of 2021, healthy adults (aged 18-45, 65-74 and 75 or older) received either one dose of BNT162b2 (n = 120) if they had a documented history of SARS-CoV-2 infection at least five months previously, or two doses (n = 147) if they had no history confirmed by negative serological tests. A first booster dose was administered at least 6 months after the primary vaccination, and a second booster dose, if any, was reported in the database. Neutralizing antibodies (NAbs) against the European (D614G) strain and the Omicron BA.1 variant were assessed up to 28 days after the first booster dose. A case-control analysis was performed for the 252 participants who were followed up in 2022, during the Omicron waves. RESULTS: From January to October 2022, 78/252 (31%) had a documented symptomatic breakthrough infection after full vaccination: 21/117 (18%) in those who had been infected before vaccination vs. 57/135 (42%) in those who had not. In a multivariate logistic regression model, factors associated with a lower risk of breakthrough infection were older age, a higher number of booster doses, and higher levels of Omicron BA.1 NAb titers in adults with infection before vaccination, but not in those without prior infection. CONCLUSION: Our results highlight the need to consider immune markers of protection in association with infection and vaccination history.

BNT162b2 COVID-19 Vaccines in Children, Adolescents and Young Adults with Cancer-A 1-Year Follow-Up.

(1) Background: Children and young adults with cancer are poorly represented in COVID-19 vaccination studies, and long-term protection conferred by vaccination is not known. (2) Objectives: 1. To determine the adverse effects associated with BNT162B2 vaccination in children and young adults with cancer. 2. To assess its efficacy in stimulating immunological response and in preventing severe COVID-19 disease. (3) Methods: Retrospective single-center study evaluating patients aged 8 to 22 years, with cancer, who underwent vaccination from January 2021 to June 2022. ELISA serologies and serum neutralization were collected monthly from the first injection. Serologies below 26 were considered negative, while those above 264 BAU/mL were considered positive and indicative of protection. Antibodies titers were considered positive above 20. Data on adverse events and infections were collected. (4) Results: 38 patients were included (M/F = 1.7, median age 16 years), of whom 63% had a localized tumor and 76% were undergoing treatment at the time of the first vaccination. Two or three vaccine injections were administered in 90% of patients. Adverse events were mainly systemic and not severe, except for seven grade 3 toxicities. Four cancer-related deaths were reported. Median serology was negative the month following the first vaccination and became protective during the third month. At 3 and 12 months, median serology was 1778 and 6437 BAU/mL, respectively. Serum neutralization was positive in 97% of the patients. COVID-19 infection occurred despite vaccination in 18%; all were mild forms. (5) Conclusions: In children and young adults with cancer, vaccination was well tolerated and conferred effective serum neutralization. COVID-19 infections were mild, and vaccine seroconversion persisted after 12 months in most patients. The value of additional vaccination should be further established.

Early humoral response to COVID-19 vaccination in patients living with obesity and diabetes in France. The COVPOP OBEDIAB study with results from the ANRS0001S COV-POPART cohort.

BACKGROUND: Patients with diabetes and obesity are populations at high-risk for severe COVID-19 outcomes and have shown blunted immune responses when administered different vaccines. Here we used the 'ANRS0001S COV-POPART' French nationwide multicenter prospective cohort to investigate early humoral response to COVID-19 vaccination in the sub-cohort ('COVPOP OBEDIAB') of patients with obesity and diabetes. METHODS: Patients with diabetes (n = 390, type 1 or 2) or obesity (n = 357) who had received two vaccine doses and had no history of previous COVID-19 infection and negative anti-nucleocapsid (NCP) antibodies were included and compared against healthy subjects (n = 573). Humoral response was assessed at baseline, at one month post-first dose (M0) and one-month post-second dose (M1), through percentage of responders (positive anti-spike SARS-CoV-2 IgG antibodies (Sabs), geometric means of Sabs; BAU/mL), proportion of individuals with anti-RBD antibodies, and proportion of individuals with anti-SARS-CoV-2-specific neutralizing antibodies (Nabs). Potential clinical and biological factors associated with weak response (defined as Sabs < 264 BAU/mL) and presence of non-reactive anti-RBD antibodies at M1 were evaluated. Univariate and multivariate regressions were performed to estimate crude and adjusted coefficients with 95 % confidence intervals. Poor glycemic control was defined as HbA1c ≥ 7.5 % at inclusion. RESULTS: Patients with diabetes, particularly type 2 diabetes, and patients with obesity were less likely to have positive Sabs and anti-RBD antibodies after the first and second dose compared to controls (p < 0.001). At M1, we found Sabs seroconversion in 94.1 % of patients with diabetes versus 99.7 % in controls, anti-RBD seroconversion in 93.8 % of patients with diabetes versus 99.1 % in controls, and Nabs seroconversion in 95.7 % of patients with diabetes versus 99.6 % in controls (all p < 0.0001). Sabs and anti-RBD seroconversion at M0 and M1 were also significantly lower in obese patients than controls, at respectively 82.1 % versus 89.9 % (p = 0.001; M0 Sabs), 94.4 % versus 99.7 % (p 0.001; M1 Sabs), 79.0 % vs 86.2 % (p = 0.004 M0 anti-RBD), and 96.99 % vs 99.1 % (p = 0.012 M1 anti-RBD). The factors associated with low vaccine response (BAU < 264/mL) in patients with diabetes were chronic kidney disease (adjusted OR = 6.88 [1.77;26.77], p = 0.005) and poor glycemic control (adjusted OR = 3.92 [1.26;12.14], p = 0.018). In addition, BMI ≥ 40 kg/m2 was found to be associated with a higher vaccine response (adjusted OR = 0.10 [0.01;0.91], p = 0.040) than patients with BMI < 40 kg/m2. CONCLUSION: COVID-19 vaccine humoral response was lower in patients with obesity and diabetes one month after second dose compared to controls, especially in diabetic patients with CKD or inadequate glycemic control. These findings point to the need for post-vaccination serological checks in these high-risk populations.

One-month humoral response following two or three doses of messenger RNA coronavirus disease 2019 vaccines as primary vaccination in specific populations in France: first results from the Agence Nationale Recherche contre le Sida (ANRS)0001S COV-POPART cohort.

OBJECTIVES: We aimed to investigate the 1-month humoral response to two or three doses of a messenger RNA coronavirus disease 2019 (COVID-19) vaccine as a primary vaccination regimen in specific populations compared with that in healthy adults. METHODS: Agence Nationale Recherche contre le Sida (ANRS)0001S-COV-POPART (NCT04824651) is a French nation-wide, multi-centre, prospective, observational cohort study assessing the immune response to COVID-19 vaccines routinely administered to 11 sub-groups of patients with chronic conditions and two control groups. Patients and controls who received at least two vaccine doses and whose results 1 month after the second dose were available were included. The humoral response was assessed 1 month after the first, second and third doses (if applicable) based on the percentage of responders (positive for anti-Spike severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] IgG antibodies), geometric means of anti-Spike SARS-CoV-2 IgG antibodies (enzyme-linked immunosorbent assay) and proportion of participants with anti-SARS-CoV-2-specific neutralizing antibodies (in vitro neutralization assay for the original SARS-CoV-2 strain). All analyses were centralized. RESULTS: We included 4091 participants in this analysis: 2979 participants from specific sub-populations and 1112 controls. Only 522 (17.5%) participants from the specific populations received three doses as a primary vaccination regimen. Patients living with human immunodeficiency virus, cancer and diabetes had high percentages of responders after two doses, whereas patients with solid organ transplants, allogeneic hematopoietic stem cell transplants and hypogammaglobulinaemia had the lowest percentage of responders (35.9% [95% CI, 29.2-43.0], 57.4% [95% CI, 48.1-66.3] and 77.1% [95% CI, 65.6-86.3], respectively). In those who received the third dose, the percentage of responders reached 54.2% (95% CI, 42.9-65.2) (vs. 32.3% [95% CI, 16.7-51.4] after 2 doses) among those with solid organ transplants and 73.9% (95% CI, 58.9-85.7) (vs. 56.1% [95% CI, 46.2-65.7] after 2 doses) among those with hematopoietic stem cell transplants. Similar results were found with anti-SARS-CoV-2-specific neutralizing antibodies. CONCLUSIONS: A lower humoral response to COVID-19 vaccines was observed in the specific populations compared with that in the controls. The third dose of this vaccine in the primary regimen had a positive effect on the percentages of patients who developed anti-Spike IgG antibodies and specific neutralizing antibodies.

Neutralizing antibodies against SARS-CoV-2 variants following mRNA booster vaccination in adults older than 65 years.

Immune response induced by COVID-19 vaccine booster against delta and omicron variants was assessed in 65 adults (65-84 years old) early aftesr a first booster dose. An increase in SARS-CoV-2 neutralizing antibodies was shown in individuals not previously infected without evidence of an age-related effect, with lower increase in those infected before a single dose of primary vaccination. Of note, humoral response was observed only starting from the 5th day after the boost.

Presence of specific SARS-COV2 antibodies in hemodialysis patients and their caregivers after the first wave of COVID-19.

Hemodialysis (HD) patients are at risk for severe COVID-19 and cannot comply with social distancing. SARS-COV2 seroprevalence in French patients and caregivers after the first wave of COVID-19 is unknown. SeroCOVIDial is a prospective study conducted between June and December 2020. SARS-COV2 seroprevalence was evaluated by a rapid serological test (BIOSYNEX) in HD patients and caregivers, and the presence or not of anti-SARS-COV2 neutralizing or non-neutralizing antibodies in patients was also determined by ELISA and seroneutralization. In June 2020, 451 HD patients and 238 caregivers were included. Overall SARS-COV2 seroprevalence was 8.4% (patients) and 6.7% (caregivers), and was 87.1% (patients) and 90.0% (caregivers) in participants with a previously documented SARS-COV2 infection. Overall seroprevalence reached 13.8% (patients) and 12.6% (caregivers) following the second epidemic wave. During the follow-up, 38 (8.4%) patients died (9 of COVID-19). Among the 44 (10.6%) patients who became infected, only two were seropositive at M0. The levels of anti-SARS-COV2 antibodies decreased over time in patients and caregivers. The BIOSYNEX test showed 82.9% sensitivity and 97.7% specificity. Prevalence of anti-SARS-COV2 antibodies was low in HD patients and caregivers after the first epidemic wave but rose after the second wave. A rapid serological test showed good performances and could be useful for future monitoring of anti-SARS-COV2 antibodies.

In vitro activity of therapeutic antibodies against SARS-CoV-2 Omicron BA.1, BA.2 and BA.5.

The replacement of the Omicron BA.1 variant of SARS-CoV-2 by the BA.2 and the rapid growth of the BA.5 sub lineage, which have both different sets of mutations in the spike glycoprotein, alters the spectrum of activity of therapeutic antibodies currently licensed in the European Union. Using clinical strains of the Omicron BA.2 and BA.5 variants, we compared the neutralising power of monoclonal antibodies against the Omicron BA.1, BA.2 and BA.5 variants, using an ancestral strain (lineage B.1, D614G) and a Delta variant strain as reference. Sotrovimab/Vir-7831 is less active against BA.2 than against BA.1 (fold change reduction ~ 1,4) and even less active against BA.5 (fold change reduction ~ 2.7). Within the Evusheld /AZD7442 cocktail, Cilgavimab/AZD1061 is more active against BA.2 and BA.5 than against BA.1 (fold change increase ~ 32), whilst the very low activity of Tixagevimab/AZD8895 against BA.1 is not enhanced against BA.2 nor BA.5. In total, compared to BA.1, the activity of the Evusheld/AZD7442 is significantly improved against BA.2 while BA.5 is intermediate but closer to BA.2.

Outbreak of central nervous system infections among children in Thai Binh, Viet Nam.

From July to October 2020, 99 cases of central nervous system (CNS) infections were identified in Thai Binh Pediatric Hospital, Viet Nam, representing a five-fold increase compared to the baseline incidence during the previous five years. Clinical data were retrospectively collected. Cerebrospinal fluid specimens (CSF) were secondarily tested for pathogens using viral culture and PCR assays. Patient median age was 5 years (0-12 years); 58.6% were male. Of these children, 83.8% had CSF white blood culture (WBC) counts of ≥ 10 cells/µL, including 58 of 99 (58.6%) with a WBC count ≥ 100 cells/µL. Overall, 72 (72.7%) patients had confirmed infections with a pathogen identified in the CSF, the majority of which (66) were enterovirus. Sequencing results suggested that the rise of incidence observed in 2020 was due to Echovirus 4 (n = 45), Echovirus 30 (n = 8), and Echovirus 6 (n = 1) circulation. A confirmed CNS infection was significantly associated with older age (≥5 years, OR = 3.64, p = 0.03) and with an increased WBC count in the CSF (OR = 6.38, p-value = 0.01 for WBCs from 10 to <100 and OR = 7.90, p-value = 0.002 for WBCs ≥100). Ninety-seven (97) of 99 (98.0%) children received empiric antimicrobial treatment, and 35 (35.3%) were treated with multiple antibiotics. Eighty-four (84) patients (84.9%) were discharged home, and 11 (11.1%) were transferred to the National Hospital because their condition had worsened. No deaths were recorded. Point-of-care tests, including real-time PCR assays to identify common pathogens, should be implemented for more accurate diagnosis and more appropriate antibiotic use.

Immunogenicity and reactogenicity of heterologous and homologous mRNA-1273 and BNT162b2 vaccination: A multicenter non-inferiority randomized trial.

Background: Although effective mRNA vaccines for SARS-CoV-2 infection have been deployed worldwide, their interchangeability could facilitate the scale-up of vaccination programs. The objective of the trial was to assess whether the immune response induced by a heterologous SARS-CoV-2 mRNA primo vaccination is non-inferior to that of a homologous mRNA vaccination. Methods: We conducted a multicenter, randomized, open-label trial in adults 18 years of age and older who received a first dose of SARS-CoV-2 mRNA vaccine. Participants were randomly assigned in a 1:1 ratio to receive a second dose of BNT162b2 or mRNA-1273, 28 to 49 days after the first dose. Randomization was stratified on the vaccine received at the first vaccination. The primary endpoint was the anti-spike IgG antibodies titer measured 28 days after the second vaccine dose. This study is registered with ClinicalTrials.gov, Trial, NCT04900467. Findings: Of the 414 randomized participants recruited from May 28 to July 2, 2021, 390 were included in the per protocol analysis: 94 participants in group 1 (BNT162b2/BNT162b2), 96 in group 2 (BNT162b2/mRNA-1273), 97 in group 3 (mRNA-1273/mRNA-1273), and 103 in group 4 (mRNA-1273/BNT162b2). The geometric mean titers ratios of anti-spike IgG antibodies for each heterologous regimen relative to the corresponding homologous regimen were 1·37 (two-sided 95% CI, 1·10 to 1·72) in the groups 1 and 2 and 0·67 (two-sided 95% CI, 0·55 to 0·82) in the groups 3 and 4. Levels of neutralizing antibodies to the main circulating SARS-Cov-2 viral strains were higher with the vaccine regimen containing mRNA-1273. Participants who received mRNA-1273 as a second dose experienced a higher rate of local adverse reactions and general symptoms than those who received BNT162b2 (p < 0·0001). Interpretation: The two SARS-CoV-2 mRNA vaccines could be used with flexibility for the second dose of COVID-19 primo vaccination. Tolerance remains good regardless of vaccine sequence although mRNA-1273 was more reactogenic. Funding: French Ministries of Solidarity and Health and Research. BNT162b2 was provided by Pfizer/BioNTech. mRNA-1273 was provided by Moderna.

Acceptance, efficacy, and safety of COVID-19 vaccination in older patients with cancer.

PURPOSE: The COVID-19 vaccination campaign began in December 2020, in France, and primarily targeted the oldest people. Our study aimed to determine the level of acceptance of vaccination in a population of older patients with cancer. METHODS: From January 2021, we offered vaccination with the BNT162b2 COVID-19 vaccine to all patients 70 years and older referred to our geriatric oncology center in Marseille University Hospital (AP-HM) for geriatric assessment before initiation of an oncological treatment. Objectives were to evaluate acceptance rate of COVID-19 vaccination and to assess vaccine safety, reactogenicity, and efficacy two months after the first dose. RESULTS: Between January 18, 2021 and May 7, 2021, 150 older patients with cancer were offered vaccination after a geriatric assessment. The majority were men (61.3%), with a mean age of 81 years. The two most frequent primary tumors were digestive (29.4%) and thoracic (18%). The vaccine acceptance rate was 82.6% and the complete vaccination rate (2 doses) reached 75.3%. Among the vaccinated patients, 15.9% reported mild side effects after the first dose and 23.4% after the second dose, mostly arm pain and fatigue. COVID-19 cases were observed in 5.1% of vaccinated patients compared with 16.7% in unvaccinated patients. Of the 22 vaccinated patients who agreed to have their serum tested, 15 had antibodies against the spike protein at day 21 after the first dose. CONCLUSION: Our study showed a high acceptance rate of COVID-19 vaccination, with good tolerance in this frail population. These results highlight the benefits of organizing vaccination campaigns at the very beginning of oncological management in older patients. CLINICAL TRIAL REGISTRATION: This study was registered May 23, 2019 in ClinicalTrials.gov (NCT03960593).

Persistent symptoms after the first wave of COVID-19 in relation to SARS-CoV-2 serology and experience of acute symptoms: A nested survey in a population-based cohort.

Background: Many patients report persistent symptoms after COVID-19. Our aim was to determine whether some of these symptoms were more associated with past SARS-CoV-2 infection compared to other conditions. Methods: This prospective survey was nested in CONSTANCES, a randomly selected French population-based cohort, started in 2012. All participants being followed-up by internet completed 2 questionnaires during the first wave of the pandemic focusing on the acute symptoms of their COVID-19-like illness. Serological tests for SARS-CoV-2 were then performed (May-Nov 2020). Between December 2020 and January 2021, participants completed a third questionnaire about symptoms that had lasted more than 2 months. Participants were classified into four groups according to both European Center for Diseases Control (ECDC) criteria for COVID-19 (ECDC+ or ECDC-) and serological SARS-CoV-2 test results (Sero+ or Sero-). To compare the risk of each persistent symptom among the groups, logistic regression models were adjusted for age, sex, educational level, comorbidities, and the number of acute symptoms declared during the first wave of the epidemic. A mediation analysis was performed to estimate the direct effect of the infection on persistent symptoms and its indirect effect via the initial clinical presentation. Findings: The analysis was performed in 25,910 participants. There was a higher risk of persistent dysgeusia/anosmia, dyspnea and asthenia in the ECDC+/Sero+ group than in the ECDC+/Sero- group (OR: 6.83 [4.47-10.42], 1.69 [1.07-2.6] and 1.48 [1.05-2.07], respectively). Abdominal pain, sensory symptoms or sleep disorders were at lower risk in the ECDC+/Sero+ group than in the ECDC+/Sero- group (0.51 [0.24-0.96], 0.40 [0.16-0.85], and 0.69 [0.49-0.95], respectively). The mediation analysis revealed that the association of the serological test results with each symptom was mainly mediated by ECDC symptoms (proportion mediated range 50-107%). Conclusion: A greater risk of persistent dysgeusia/anosmia, dyspnea and asthenia was observed in SARS-CoV-2 infected people. The initial clinical presentation substantially drives the association of positive serological test results with persistent symptoms. Funding: French National Research Agency.

Epidemiological and clinical insights from SARS-CoV-2 RT-PCR crossing threshold values, France, January to November 2020.

BackgroundThe COVID-19 pandemic has led to an unprecedented daily use of RT-PCR tests. These tests are interpreted qualitatively for diagnosis, and the relevance of the test result intensity, i.e. the number of quantification cycles (Cq), is debated because of strong potential biases.AimWe explored the possibility to use Cq values from SARS-CoV-2 screening tests to better understand the spread of an epidemic and to better understand the biology of the infection.MethodsWe used linear regression models to analyse a large database of 793,479 Cq values from tests performed on more than 2 million samples between 21 January and 30 November 2020, i.e. the first two pandemic waves. We performed time series analysis using autoregressive integrated moving average (ARIMA) models to estimate whether Cq data information improves short-term predictions of epidemiological dynamics.ResultsAlthough we found that the Cq values varied depending on the testing laboratory or the assay used, we detected strong significant trends associated with patient age, number of days after symptoms onset or the state of the epidemic (the temporal reproduction number) at the time of the test. Furthermore, knowing the quartiles of the Cq distribution greatly reduced the error in predicting the temporal reproduction number of the COVID-19 epidemic.ConclusionOur results suggest that Cq values of screening tests performed in the general population generate testable hypotheses and help improve short-term predictions for epidemic surveillance.

High SARS-CoV-2 Prevalence among Healthcare Workers in Cochabamba, Bolivia.

Healthcare workers (HCWs) are at increased risk of SARS-CoV-2 infection. The aim of the study was to estimate the SARS-CoV-2 seroprevalence among HCWs in Cochabamba, Bolivia and to determine the potential risk factors. In January 2021, a cross-sectional SARS-CoV-2 seroprevalence study was conducted in 783 volunteer clinical and non-clinical HCWs in tertiary care facilities. It was based on IgG detection using ELISA, chemiluminiscence, and seroneutralisation tests from dried blood spots. Analysis revealed a high seroprevalence (43.4%) of SARS-CoV-2 IgG antibodies. The combination of anosmia and ageusia (OR: 68.11; 95%-CI 24.83-186.80) was predictive of seropositivity. Belonging to the cleaning staff (OR: 1.94; 95%-CI 1.09-3.45), having more than two children in the same house (OR: 1.74; 95%-CI 1.12-2.71), and having been in contact with a close relative with COVID-19 (OR: 3.53; 95%-CI 2.24-5.58) were identified as risk factors for seropositivity in a multivariate analysis. A total of 47.5% of participants had received medication for COVID-19 treatment or prevention, and only ~50% of symptomatic subjects accessed PCR or antigenic testing. This study confirms a massive SARS-CoV-2 attack rate among HCWs in Cochabamba by the end of January 2021. The main risk factors identified are having a low-skilled job, living with children, and having been in contact with an infected relative in the household.