Dynamics of the seroprevalence of SARS-CoV-2 antibodies among healthcare workers at a COVID-19 referral hospital in Milan, Italy

Seroprevalence of SARS-CoV-2 in hospital workers in the southern region of Minas Gerais state in Brazil: An analysis of the pre-vaccine period

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection seroprevalence can be performed by detecting anti-SARS-CoV-2 antibodies. The survey is essential to understand the disease transmission's dynamic in the studied population. This study aimed to carry out a seroepidemiological survey of SARS-CoV-2 in three hospitals located in the south of Minas Gerais state, Brazil. 859 samples were collected from August to December 2020 when SARS-CoV-2 vaccines were still not available and Enzyme-linked immunosorbent assays (ELISA) were performed on participants sera. The average age of participants was 38 years, and most were women (71.4%). Likewise, most participants were classified as health professionals with direct or indirect contact with patients with COVID-19 (74.5%). The other participants tested belonged to other sectors, such as the administrative one (11,6%). Considering clinical symptoms, 15.8% of participants reported diarrhoea, 6.4% fever, 5.8% respiratory distress, and 7.0% loss of smell and taste. Many participants reported contact with infected patients (63.35%). Regarding the ELISA tests, 21.6% of the participants had positive results and hospital 3 had the highest positivity (21.7%), followed by hospital 2 (21.6%) and hospital 1 (20.3%). The prevalence was higher in women compared to men (22,8% and 18,7%, respectively). Regarding the area of expertise, the highest positivity (20.9%) was observed among health professionals. However, professionals who worked exclusively with COVID-19 had lower positivity when compared to professionals who did not work directly with COVID-19 (22.0% and 21.5%, respectively). When analysing the correlation between the ELISA tests with the other variables, a significant association was detected with these previous serological variables, previous contact with COVID-19 and the presence of fever symptoms, loss of smell and taste. Clinical symptoms associated with serological tests are important tools for monitoring the disease among health professionals.

Cumulative incidence of SARS-CoV-2 infection within the homeless population: insights from a city-wide longitudinal study

OBJECTIVES

The aim of this study was to determine the risk factors associated with SARS-CoV-2 infection in a cohort of homeless people using survival analysis. Seroprevalence in the homeless community was also compared with that of the general population.

DESIGN

Cohort study.

SETTING

Data were collected across two testing sessions, 3 months apart, during which each participant was tested for anti-SARS-CoV-2 antibodies and completed a face-to-face survey.

PARTICIPANTS

All homeless adults sleeping rough, in slums or squats, in emergency shelters or transitional accommodation in Marseille were eligible.

PRIMARY OUTCOME MEASURES

Occurrence of a seroconversion event defined as a biologically confirmed SARS-CoV-2 infection. Local data from a national seroprevalence survey were used for comparison between homeless people and the general population.

RESULTS

A total of 1249 people were included. SARS-CoV-2 seroprevalence increased from 6.0% (4.7-7.3) during the first session to 18.9% (16.0-21.7) during the second one, compared with 3.0% (1.9-4.2) and 6.5% (4.5-8.7) in the general population. Factors significantly associated with an increased risk of COVID-19 infection were: having stayed in emergency shelters (1.93 (1.18-3.15)), being an isolated parent (1.64 (1.07-2.52)) and having contact with more than 5-15 people per day (1.84 (1.27-2.67)). By contrast, smoking (0.46 (0.32-0.65)), having financial resources (0.70 (0.51-0.97)) and psychiatric or addictive comorbidities (0.52 (0.32-0.85)) were associated with a lower risk.

CONCLUSION

We confirm that homeless people have higher infection rates than the general population, with increased risk in emergency shelters. There is growing evidence that, in addition to usual preventive measures, public policies should pay attention to adapt the type of accommodation and overall approach of precariousness.

TRIAL REGISTRATION NUMBER

NCT04408131.

SARS-CoV-2 Antibody Dynamics in Healthcare Workers after mRNA Vaccination

Since the emergence of SARS-CoV-2, maintaining healthcare worker (HCW) health and safety has been fundamental to responding to the global pandemic. Vaccination with mRNA-base vaccines targeting SARS-CoV-2 spike protein has emerged as a key strategy in reducing HCW susceptibility to SARS-CoV-2, however, neutralizing antibody responses subside with time and may be influenced by many variables. We sought to understand the dynamics between vaccine products, prior clinical illness from SARS-CoV-2, and incidence of vaccine-associated adverse reactions on antibody decay over time in HCWs at a university medical center. A cohort of 296 HCWs received standard two-dose vaccination with either bnt162b2 (Pfizer/BioNTech) or mRNA-1273 (Moderna) and were evaluated after two, six, and nine months. Subjects were grouped by antibody decay curve into steep antibody decliners gentle decliners. Vaccination with mRNA-1273 led to more sustained antibody responses compared to bnt162b2. Subjects experiencing vaccine-associated symptoms were more likely to experience a more prolonged neutralizing antibody response. Subjects with clinical SARS-CoV-2 infection prior to vaccination were more likely to experience vaccination-associated symptoms after first vaccination and were more likely to have a more blunted antibody decay. Understanding factors associated with vaccine efficacy may assist clinicians in determining appropriate vaccine strategies in HCWs.

Time Analysis of an Emergent Infection Spread Among Healthcare Workers: Lessons Learned from Early Wave of SARS-CoV-2

Aim

To find whether an emergent airborne infection is more likely to spread among healthcare workers (HCW) based on data of SARS-CoV-2 and whether the number of new cases of such airborne viral disease can be predicted using a method traditionally used in weather forecasting called Autoregressive Fractionally Integrated Moving Average (ARFIMA).

Methods

We analyzed SARS-CoV-2 spread among HCWs based on outpatient nasopharyngeal swabs for real-time polymerase chain reaction (RT-PCR) tests and compared it to non-HCW in the first and the second wave of the pandemic. We also generated an ARFIMA model based on weekly case numbers from February 2020 to April 2021 and tested it on data from May to July 2021.

Results

Our analysis of 8998 tests in the 15 months period showed a rapid rise in positive RT-PCR tests among HCWs during the first wave of pandemic. In the second wave, however, positive patients were more commonly non-HCWs. The ARFIMA model showed a long-memory pattern for SARS-CoV-2 (seven months) and predicted future new cases with an average error of ±1.9 cases per week.

Conclusion

Our data indicate that the virus rapidly spread among HCWs during the first wave of the pandemic. Review of published literature showed that this was the case in multiple other areas as well. We therefore suggest strict policies early in the emergence of a new infection to protect HCWs and prevent spreading to the general public. The ARFIMA model can be a valuable forecasting tool to predict the number of new cases in advance and assist in efficient planning.

COVID-19 hospital admissions and mortality among healthcare workers in South Africa, 2020-2021

Objectives

This study describes the characteristics of admitted HCWs reported to the DATCOV surveillance system, and the factors associated with in-hospital mortality in South African HCWs.

Methods

Data from March 5, 2020 to April 30, 2021 were obtained from DATCOV, a national hospital surveillance system monitoring COVID-19 admissions in South Africa. Characteristics of HCWs were compared with those of non-HCWs. Furthermore, a logistic regression model was used to assess factors associated with in-hospital mortality among HCWs.

Results

In total, there were 169 678 confirmed COVID-19 admissions, of which 6364 (3.8%) were HCWs. More of these HCW admissions were accounted for in wave 1 (48.6%; n = 3095) than in wave 2 (32.0%; n = 2036). Admitted HCWs were less likely to be male (28.2%; n = 1791) (aOR 0.3; 95% CI 0.3-0.4), in the 50-59 age group (33.1%; n = 2103) (aOR 1.4; 95% CI 1.1-1.8), or accessing the private health sector (63.3%; n = 4030) (aOR 1.3; 95% CI 1.1-1.5). Age, comorbidities, race, wave, province, and sector were significant risk factors for COVID-19-related mortality.

Conclusion

The trends in cases showed a decline in HCW admissions in wave 2 compared with wave 1. Acquired SARS-COV-2 immunity from prior infection may have been a reason for reduced admissions and mortality of HCWs despite the more transmissible and more severe beta variant in wave 2.

COVID-19 cases among medical laboratory services staff in South Africa, 2020–2021: A cohort study

Medical laboratory workers may have an increased risk of COVID-19 due to their interaction with biological samples received for testing and contamination of documents. Records of COVID-19 laboratory-confirmed positive cases within the medical laboratory service were routinely collected in the company’s Occupational Health and Safety Information System (OHASIS). Surveillance data from the OHASIS system were extracted from 1 April 2020 to 31 March 2021. An epidemic curve was plotted and compared to that for the country, along with prevalence proportions and incidence rates. The odds of COVID-19 infection were categorised by job and compared to the US Occupational Risk Scores. A logistic regression model assessed the risk of COVID-19 infection per occupational group. A total of 2091 (26% of staff) COVID-19 positive cases were reported. The number of COVID-19 cases was higher in the first wave at 46% (967/2091) of cases, than in the second wave 40% (846/2091) of cases. There was no significant difference in COVID-19 prevalence between male and female employees. The job categories with the most increased risk were laboratory managers [AOR 3.2 (95%CI 1.9–5.1)] and laboratory support clerks [AOR 3.2 (95%CI 1.9–5.2)]. Our study confirms that some categories of medical laboratory staff are at increased risk for COVID-19; this is a complex interaction between workplace risk factors, community interaction, socioeconomic status, personal habits, and behaviour. Targeted interventions are recommended for high-risk groups. OHASIS has the potential to generate data for surveillance of health care workers and contribute towards a South African risk profile.

Evidence of SARS-CoV-2 Antibodies and RNA on Autopsy Cases in the Pre-Pandemic Period in Milan (Italy)

In this study, we analyzed blood samples obtained from 169 cadavers subjected to an autopsy from 1 October 2019 to 27 March 2020. The presence of anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) antibodies was searched by lateral flow immunochromatographic assay (LFIA) and ELISA tests and the SARS-CoV-2 RNA was tested in blood and available lung tissues by real-time PCR (RT-PCR) and droplet digital PCR (ddPCR). Five cases resulted in positives at the serological screening for anti-SARS-CoV-2. Three results were weakly positive for IgM while only one showed strong reactivity for IgG antibodies. The fifth subject (who died in December 2019) resulted positive for the ELISA test. The detection of SARS-CoV-2 RNA resulted in positive only in the blood and lung tissues of such cases. These data suggest that cadaveric blood may be a suitable substrate for the assessment of SARS-CoV-2 infection; moreover, they extend the observations of sporadic cases of SARS-CoV-2 infection in North Italy prior to the first confirmed cases.

Prevalence of SARS-CoV-2 infection and SARS-CoV-2-specific antibody detection among healthcare workers and hospital staff of a university hospital in Colombia

•

The prevalence of SARS-CoV-2 infection among hospital workers in a Colombian university hospital was low.

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The presence of antibodies against the virus was high among healthcare workers.

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Some professions showed a higher chance of being SARS-CoV-2 seropositive.

Objective

The aim of this study was to determine current and previous SARS-COV-2 infection, and describe risk factors associated with seropositivity, among HCWs and hospital staff between June and October of 2020.

Methodology

Data from the day of enrollment for a prospective cohort study were analyzed to determine point prevalence and seroprevalence of SARS-CoV-2 infection in HCWs and hospital staff of a university hospital in Colombia. Respiratory samples were collected to perform RT-PCR tests, along with blood samples to measure SARS-CoV-2 IgM and IgG antibodies. Data on nosocomial and community risk factors for infection were also collected and analyzed.

Findings

420 HCWs and hospital staff members were included. The seroprevalence at baseline was 23.2%, of which 10.7% had only IgM antibodies, 0.7% had IgG, and 11.7% had IgM and IgG. The prevalence of acute SARS-CoV-2 infection was 1.9%. Being a nurse assistant was significantly associated with seropositivity when compared with all other job duties (PR 2.39, 95% CI 1.27–3.65, p = 0.01).

Conclusions

Overall SARS-CoV-2 prevalence was 1.9% and seroprevalence was 23.15%. Nurse assistants, medical doctors or students, and laboratory workers had a higher possibility of being SARS-CoV-2 seropositive.

Seroprevalence of anti-SARS-CoV-2 antibodies among staff at primary healthcare institutions in Prishtina

BACKGROUND

Many studies examined the spread of SARS-CoV-2 within populations using seroprevalence. Healthcare workers are a high-risk population due to patient contact, and studies are needed to examine seroprevalence of SARS-CoV-2 antibodies among healthcare workers. Our study investigates the seroprevalence of anti-SARS-CoV-2 antibodies among staff at primary healthcare institutions in Prishtina, and factors associated with seroprevalence.

METHODS

We carried out a cross-sectional survey including SARS-CoV-2 serological testing and questionnaires with primary healthcare workers from primary healthcare facilities in the Prishtina, the capital city of Kosovo. We calculated prevalence of anti-SARS-CoV-2 antibodies, and of self-reported positive PCR test among primary healthcare workers, as well as crude and adjusted ORs for explanatory factors.

RESULTS

Eighty-three of the healthcare workers (17.47%) tested positive for SARS-CoV-2 antibodies IgG or IgM, while 231 (48.63%) either had antibodies or a previous positive PCR test. Odds of seropositivity were affected by male gender (OR 2.08, 95% CI 1.20, 3.61), and infected family members (OR 3.61, 95% CI 2.25, 5.79) of healthcare workers. Higher education, being part of larger families and having infected family members gave higher odds of positive PCR test and seropositivity. Other healthcare workers had lower odds of positive PCR test and seropositivity than physicians.

CONCLUSION

Over 17% of healthcare workers were seropositive for SARS-CoV-2 antibodies and close to half of them were either seropositive or PCR self-reported positive test. Several factors are associated with decreased and increased odds for such outcomes. These findings should be explored further and addressed to Kosovo policy makers, and assist them to intensify vaccination efforts, and maintain control measures until we achieve herd immunity.

Impact of prior infection status on antibody response to the BNT162b2 mRNA COVID-19 vaccine in healthcare workers at a COVID-19 referral hospital in Milan, Italy

In Italy, SARS-CoV-2 vaccination campaign prioritized healthcare workers (HCWs) to receive two doses of BNT162b2 vaccine, irrespective of a previous SARS-CoV-2 infection. In this real-life study, we compared the humoral response to BNT162b2 vaccine in HCWs with and without a previous SARS-CoV-2 infection. Of the 407 HCWs enrolled, 334 (82.1%) were SARS-CoV-2-naive and 73 (17.9%) SARS-CoV-2-experienced. Post-vaccine humoral response was detectable in more than 98% of HCWs. Overall, the median level of anti-S IgG in SARS-COV-2-experienced HCWs was twice as high as those of SARS-CoV-2-naive subjects (24641.0 AU/mL [IQR: 15273.0->40000.0] versus 13053.8 [IQR: 7303.3-20105.8]; p < .001), irrespective of the time elapsed from SARS-CoV-2 previous infection. In a subgroup of SARS-CoV-2-naive and -experienced subjects who received only one dose of the vaccine, the latter showed 32 times higher levels of anti-S IgG compared to the former. Although no serious adverse events have been reported, mild to moderate side effects occurred more frequently after the first dose in the SARS-CoV-2-experienced than in naive subjects (67% versus 42%, respectively; p < .001). Notably, post-vaccination anti-SARS-CoV-2 spike IgG levels ≥20,000 AU/mL were independently associated with the risk of fever ≥38°C (adjusted odds ratio [aOR] 5.122, 95% CI 2.368-11.080, p < .0001).Our study showed high responsiveness of BNT162b2 vaccine and a relationship between levels of antibody response and reactogenicity. It suggests that a single dose of mRNA vaccine might evoke effective protection in SARS-CoV-2-experienced subjects.

Seroprevalence of the SARS-CoV-2 antibody in healthcare workers: a multicentre cross-sectional study in 10 Colombian cities

BACKGROUND

Healthcare workers are at increased risk of infection due to occupational exposure to SARS-CoV-2-infected patients. The objective of this study was to determine the seroprevalence of SARS-CoV-2 in healthcare workers in Colombia.

METHODS

This study is a cross-sectional study focused on estimating the seroprevalence of SARS-CoV-2 antibodies in healthcare workers from 65 hospitals in 10 cities in Colombia during the second semester of 2020. The seroprevalence was determined using an automated immunoassay (Abbott SARS-CoV-2 CLIA IgG). The study included a survey to establish the sociodemographic variables and the risk of infection. A multivariate model was used to evaluate the association between the results of seroprevalence and risk factors.

RESULTS

The global seroprevalence of antibodies against SARS-CoV-2 was 35% (95% Bayesian CI 33% to 37%). All the personnel reported the use of protective equipment. General services personnel and nurses presented the highest ratios of seroprevalence among the healthcare workers. Low socioeconomic strata have shown a strong association with seropositivity.

CONCLUSION

This study estimates the prevalence of SARS-CoV-2 infection among healthcare workers. Even though all the personnel reported the use of protective equipment, the seroprevalence in the general services personnel and nurses was high. Also, a significant difference by cities was observed.

Nasopharyngeal Testing among Healthcare Workers (HCWs) of a Large University Hospital in Milan, Italy during Two Epidemic Waves of COVID-19

BACKGROUND

since October 2020, a second SARS-CoV-2 epidemic wave has hit Italy. We investigate the frequency of positive nasopharyngeal swabs among HCWs during the two waves and the association with occupation and demographic characteristics.

METHODS

this is a retrospective, observational study conducted in a large university hospital in Milan, Northern Italy. We defined two epidemic waves: 1st (February 2020-July 2020) and 2nd (August 2020-January 2021). Occupational and demographic characteristics of HCWs who underwent nasopharyngeal swabs for SARS-CoV-2 were collected.

RESULTS

in the 1st wave, 242 positive subjects (7.2%) were found among 3378 HCWs, whereas in the 2nd wave, the positive subjects were 545 out of 4465 (12.2%). In both epidemic waves positive NPSs were more frequent among HCWs with health-related tasks and lower among students (p < 0.001). However, in the 2nd wave, workers engaged in non-health-related tasks had a peak of 20.7% positivity. Among 160 positive HCWs in the 1st wave who were tested again in the 2nd wave, the rate of reinfection based on SARS-CoV2 RNA cycle quantification value was 0.6%.

CONCLUSIONS

during the 2nd epidemic wave, we confirmed a significant impact of COVID-19 among HCWs. The rise of infection rate among HCWs seems to reflect the increasing spread of SARS-CoV-2 among the overall population.

Understanding COVID-19 Epidemiology and Implications for Control: The Experience from a Greek Semi-Closed Community

BACKGROUND

We aimed to estimate the SARS-CoV-2 antigen and antibody seroprevalence in one of the worst-affected by the pandemic semi-closed communities in Greece, Deskati, and evaluate the sociodemographic and clinical correlations of functional antibody responses.

METHODS

The Ag2019n-CoV V1310/V1330 Rapid Test (Prognosis Biotech, Greece) was used for antigen detection. The Rapid Test 2019-nCoV Total Ig, V1210/V1230 (Prognosis Biotech, Greece), and the SARS-CoV-2 IgG II Quant method (Architect, Abbott, Illinois, USA) were used for antibody testing.

RESULTS

None of the participants had a positive antigen result. SARS-CoV-2 seropositivity ranged from 13% to 45% in the study population, depending on the method. One-third of the participants with known past infection had a positive antibody test result 77 ± 13 days after infection. Two-fifths of infections determined by serology were asymptomatic. The advancing age and hospitalization predicted seropositivity among patients with past infection. Half of the participants who tested positive for antibodies were not aware of past infection.

CONCLUSIONS

High-burden contexts in Greece, such as Deskati, are not so far from herd immunity thresholds. We highlighted the value of low-cost serosurveys targeting both symptomatic and asymptomatic populations to evaluate the natural immune response to SARS-CoV-2 in nonvaccinated susceptibles and design evidence-based policies for lifting lockdowns.

Longitudinal assessment of SARS-CoV-2 IgG seroconversionamong front-line healthcare workers during the first wave of the Covid-19 pandemic at a tertiary-care hospital in Chile

Background

Healthcare workers (HCWs) are at high risk of exposure to SARS-CoV-2. Cross-sectional studies have provided variable rates of seroprevalence in HCWs. Longitudinal assessments of the serological response to Covid-19 among HCWs are crucial to understanding the risk of infection and changes in antibody titers over time. We aimed to investigate seroprevalence and risk factors associated with seroconversion in a prospective cohort of HCWs during the peak of the first wave of the Covid-19 pandemic.

Methods

We conducted a longitudinal study among 446 front-line HCWsin a tertiary-care hospital in Chile from April to July 2020. IgG was determined monthly using two different ELISAs in serum samples of HCWs, during the three-month period. In each visit, demographic data, symptoms, risk factors, and exposure risks were also assessed.

Results

The overall seroprevalence at the end of the study period was 24% (95% CI20.2–28.3), with 43% of seropositive HCWs reporting no prior symptoms. Seroconversion rates significantly differed over the study period, from 2.1% to as high as 8.8% at the peak of the epidemic. There were no statistically significant differences observed between HCWs in direct clinical care of patients with Covid-19 and those working in low risk areas. Antibody titers appeared to wane over time.

Conclusions

HCWs were severely affected with a high rate of seroconversion that appeared to mirror the local epidemiological situation. A significant amount of participants underwent an asymptomatic infection, highlighting the need for improved surveillance policies. Antibody titers appear to wane over time; further studies to understand this finding’s impact on the risk of reinfection are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06208-2.

SARS-CoV-2 Seroprevalence in Healthcare Workers in Germany: A Follow-Up Study

SARS-CoV-2 is a worldwide challenge for the medical sector. Healthcare workers (HCW) are a cohort vulnerable to SARS-CoV-2 infection due to frequent and close contact with COVID-19 patients. However, they are also well trained and equipped with protective gear. The SARS-CoV-2 IgG antibody status was assessed at three different time points in 450 HCW of the University Hospital Essen in Germany. HCW were stratified according to contact frequencies with COVID-19 patients in (I) a high-risk group with daily contacts with known COVID-19 patients (n = 338), (II) an intermediate-risk group with daily contacts with non-COVID-19 patients (n = 78), and (III) a low-risk group without patient contacts (n = 34). The overall seroprevalence increased from 2.2% in March-May to 4.0% in June-July to 5.1% in October-December. The SARS-CoV-2 IgG detection rate was not significantly different between the high-risk group (1.8%; 3.8%; 5.5%), the intermediate-risk group (5.1%; 6.3%; 6.1%), and the low-risk group (0%, 0%, 0%). The overall SARS-CoV-2 seroprevalence remained low in HCW in western Germany one year after the outbreak of COVID-19 in Germany, and hygiene standards seemed to be effective in preventing patient-to-staff virus transmission.