Potential SARS-CoV-2 infectiousness among asymptomatic healthcare workers

A majority of SARS-CoV-2 infections are transmitted from a minority of infected subjects, some of which may be symptomatic or pre-symptomatic. We aimed to quantify potential infectiousness among asymptomatic healthcare workers (HCWs) in relation to prior or later symptomatic disease. We previously (at the onset of the SARS-CoV-2 epidemic) performed a cohort study of SARS-CoV-2 infections among 27,000 healthcare workers (HCWs) at work in the capital region of Sweden. We performed both SARS-CoV-2 RT-PCR and serology. Furthermore, the cohort was comprehensively followed for sick leave, both before and after sampling. In the present report, we used the cohort database to quantify potential infectiousness among HCWs at work. Those who had sick leave either before or after sampling were classified as post-symptomatic or pre-symptomatic, whereas the virus-positive subjects with no sick leave were considered asymptomatic. About 0.2% (19/9449) of HCW at work were potentially infectious and pre-symptomatic (later had disease) and 0.17% (16/9449) were potentially infectious and asymptomatic (never had sick leave either before nor after sampling). Thus, 33% and 28% of all the 57 potentially infectious subjects were pre-symptomatic or asymptomatic, respectively. When a questionnaire was administered to HCWs with past infection, only 10,5% of HCWs had had no indication at all of having had SARS-CoV-2 infection (“truly asymptomatic”). Our findings provide a unique quantification of the different groups of asymptomatic, potentially infectious HCWs.

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Eastern Cape Healthcare Workers Acquisition of SARS-CoV-2 (ECHAS): Cross-Sectional (Nested Cohort) Study Protocol

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18010323 ◽

2021 ◽

Vol 18 (1) ◽

pp. 323

Author(s):

Oladele Vincent Adeniyi ◽

David Stead ◽

Mandisa Singata-Madliki ◽

Joanne Batting ◽

Leo Hyera ◽

...

Keyword(s):

Cohort Study ◽

Infection Rate ◽

Healthcare Workers ◽

Health Facilities ◽

Control Measures ◽

Infection Prevention And Control ◽

Eastern Cape ◽

Rt Pcr ◽

Cross Sectional ◽

Increased Risk

Healthcare workers (HCWs) are at increased risk of infection by the virulent severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Though data exist on the positivity rate of the SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) test as well as COVID-19-related deaths amongst HCWs in South Africa, the overall infection rate remains underestimated by these indicators. It is also unclear whether the humoral immune response after SARS-CoV-2 infection offers durable protection against reinfection. This study will assess the SARS-CoV-2 seroprevalence amongst HCWs in the Eastern Cape (EC) and examine the longitudinal changes (rate of decay) in the antibody levels after infection in this cohort. Using a multi-stage cluster sampling of healthcare workers in selected health facilities in the EC, a cross-sectional study of 2250 participants will be recruited. In order to assess the community infection rate, 750 antenatal women in the same settings will be recruited. Relevant demographic and clinical characteristics will be obtained by a self-administered questionnaire. A chemiluminescent microparticle immunoassay (CMIA) will be used for the qualitative detection of IgG antibodies against SARS-CoV-2 nucleocapsid protein. A nested cohort study will be conducted by performing eight-weekly antibody assays (X2) from 201 participants who tested positive for both SARS-CoV-2 RT-PCR and serology. Logistic regression models will be fitted to identify the independent risk factors for SARS-CoV-2 infection. The cumulative SARS-CoV-2 infection rate and infection fatality rate among the frontline HCWs will be estimated. In addition, the study will highlight the overall effectiveness of infection prevention and control measures (IPC) per exposure sites/wards at the selected health facilities. Findings will inform the South African Department of Health’s policies on how to protect HCWs better as the country prepares for the second wave of the SARS-CoV pandemic.

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Survival analysis of time to SARS-CoV-2 PCR negativisation to optimise PCR prescription in health workers: the Henares COVID-19 healthcare workers cohort study

Occupational and Environmental Medicine ◽

10.1136/oemed-2020-106903 ◽

2021 ◽

pp. oemed-2020-106903

Author(s):

Julio González Martin-Moro ◽

Marta Chamorro Gómez ◽

Galicia Dávila Fernández ◽

Ana Elices Apellaniz ◽

Ana Fernández Hortelano ◽

...

Keyword(s):

Cohort Study ◽

Healthcare Workers ◽

Cox Regression ◽

Health Workers ◽

Upper Respiratory Tract ◽

Rt Pcr ◽

Kaplan Meier ◽

Confounding Variables ◽

The Impact ◽

Associated Variables

ObjectivesReverse transcriptase PCR (RT-PCR) is considered the gold standard in diagnosing COVID-19. Infected healthcare workers do not go back to work until RT-PCR has demonstrated that the virus is no longer present in the upper respiratory tract. The aim of this study is to determine the most efficient time to perform RT-PCR prior to healthcare workers’ reincorporation.Materials and methodsThis is a cohort study of healthcare workers with RT-PCR-confirmed COVID-19. Data were collected using the medical charts of healthcare workers and completed with a telephone interview. Kaplan-Meier curves were used to determine the influence of several variables on the time to RT-PCR negativisation. The impact of the variables on survival was assessed using the Breslow test. A Cox regression model was developed including the associated variables.Results159 subjects with a positive RT-PCR out of 374 workers with suspected COVID-19 were included. The median time to negativisation was 25 days from symptom onset (IQR 20–35 days). Presence of IgG, dyspnoea, cough and throat pain were associated with significant longer time to negativisation. Cox logistic regression was used to adjust for confounding variables. Only dyspnoea and cough remained in the model as significant determinants of prolonged negativisation time. Adjusted HRs were 0.68 (0.48–096) for dyspnoea and 0.61 (0.42–0.88) for dry cough.ConclusionsRT-PCR during the first 3 weeks leads to a high percentage of positive results. In the presence of respiratory symptoms, negativisation took nearly 1 week more. Those who developed antibodies needed longer time to negativisate.

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COVID-19-Related Symptoms Among Cancer Patients and Healthcare Workers— First Results From the PAPESCO-19 Prospective Cohort Study

10.20944/preprints202103.0292.v1 ◽

2021 ◽

Author(s):

Ke Zhou ◽

Audrey Blanc-Lapierre ◽

Valérie Seegers ◽

Michèle Boisdron-Celle ◽

Frédéric Bigot ◽

...

Keyword(s):

Cohort Study ◽

Cancer Patients ◽

Healthcare Workers ◽

Rt Pcr ◽

Cancer Treatments ◽

Multicenter Cohort Study ◽

Symptom Pattern ◽

C Statistic ◽

First Results ◽

After Cancer

Background: Cancer patients may fail to distinguish COVID-19 symptoms such as anosmia, dysgeusia/ageusia, anorexia, headache, and fatigue, which are frequent after cancer treatments. We aimed to identify symptoms associated with COVID-19 and to assess the strength of their association in cancer and cancer-free populations. Methods: The prospective multicenter cohort study PAPESCO-19 included 878 cancer patients and 940 healthcare workers (HCWs) systematically tested for SARS-CoV-2-specific antibodies. Participants reported the results of routine screening RT-PCR and thirteen COVID-19 symptoms. Backward logistic regression identified the symptom combinations significantly associated with COVID-19. Results: COVID+ proportions were similar in patients (8%) and HCWs (9.5%, p=0.26), whereas symptomatic proportions were lower in patients (32%) than HCWs (52%, p&lt;0.001). Anosmia, anorexia, fever, headache, and rhinorrhea together accurately discriminated (c-statistic=0.7027) COVID-19 cases in patients. Anosmia, dysgeusia/ageusia, muscle pain, intense fatigue, headache, and chest pain better discriminated (c-statistic=0.8830) COVID-19 cases in HCWs. Anosmia had the strongest association in patients (OR=7.48, 95% CI: 2.96–18.89) and HCWs (OR=5.71, 95% CI: 2.21–14.75). Conclusions: COVID-19 symptoms and their diagnostic performance differ in cancer patients and HCWs. Anosmia is associated with COVID-19 for patients, while dysgeusia/ageusia are not. Cancer patients deserve tailored preventive measures due to their particular COVID-19 symptom pattern.

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Can individuals with low antibody responses to vaccines against other viruses acquire adequate SARS-CoV-2 antibody after vaccination with the BNT162b2 mRNA vaccine?

10.1101/2021.12.26.21268358 ◽

2021 ◽

Author(s):

Wataru Ogura ◽

Kouki Ohtsuka ◽

Sachiko Matsuura ◽

Takahiro Okuyama ◽

Satsuki Matsushima ◽

...

Keyword(s):

Cohort Study ◽

Neutralizing Antibodies ◽

Healthcare Workers ◽

Neutralizing Antibody ◽

Antibody Responses ◽

Antibody Activity ◽

Low Responders ◽

Before And After ◽

Positive Threshold ◽

Antibody Levels

Objective In Japan, healthcare workers (HCWs) are vaccinated against coronavirus disease (COVID-19) and other contagious viruses (measles, rubella, chickenpox, mumps, and hepatitis B) to prevent nosocomial infection. However, some do not produce sufficient antibodies after vaccination (low responders). This study investigated changes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody levels among HCWs after SARS-CoV-2 vaccination and assessed whether low responders produced adequate SARS-CoV-2 anti-spike and neutralizing antibodies. Methods We conducted a prospective cohort study of HCWs before and after vaccination with the BNT162b2 mRNA vaccine in a hospital in Tokyo, Japan. The HCWs received two doses of BNT162b2 vaccine, 3 weeks apart. Those whose antibody levels against previous antiviral vaccines did not reach protective antibody levels after receiving two doses were defined as low responders, whereas those who produced adequate antibodies were defined as normal responders. SARS-CoV-2 anti-spike antibodies were measured 11 times from before the first BNT162b2 vaccination to 5 months after the second vaccination. SARS-CoV-2 neutralizing antibody activity was measured twice in low responders, 1 week to 1 month and 5 months after the second vaccination. Results Fifty HCWs were included in the analytic cohort. After vaccination, SARS-CoV-2 anti-spike antibody was detectable in the samples from both responders at each timepoint, but the level was lower at 5 months than at 1 week after the second vaccination. Low responders had SARS-CoV-2 neutralizing antibody activity 1 week to 1 month after the second vaccination, which exceeded the positive threshold after 5 months. Conclusion After BNT162b2 vaccination, low responders acquired adequate SARS-CoV-2 anti-spike and SARS-CoV-2 neutralizing antibodies to prevent SARS-CoV-2. However, SARS-CoV-2 anti-spike antibody levels were lower at 5 months than at 1 week after the second dose of BNT162b2 vaccine in low and normal responders. Therefore, low responders should also receive a third dose of BNT162b2 vaccine.

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Sick leave before and after the age of 65 in 2000 and 2005: a Swedish register-based cohort study

European Journal of Public Health ◽

10.1093/eurpub/ckw165.078 ◽

2016 ◽

Vol 26 (suppl_1) ◽

Author(s):

K Farrants ◽

L Kjeldgård ◽

S Marklund ◽

K Alexanderson

Keyword(s):

Cohort Study ◽

Sick Leave ◽

Before And After

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Influence of Handprint Culture Training on Compliance of Healthcare Workers with Hand Hygiene

Interdisciplinary Perspectives on Infectious Diseases ◽

10.1155/2018/3727521 ◽

2018 ◽

Vol 2018 ◽

pp. 1-6

Author(s):

Hala Fouad ◽

Mona M. A. Halim ◽

HebatAllah F. Algebaly ◽

Nardeen A. Elmallakh

Keyword(s):

Cardiac Surgery ◽

Cohort Study ◽

Hand Hygiene ◽

Bacterial Growth ◽

Healthcare Workers ◽

Visual Observation ◽

Blood Cultures ◽

Healthcare Associated Infections ◽

Before And After ◽

Healthcare Associated

Objective. We aimed to study the effect of visual observation of bacterial growth from handprints on healthcare workers’ (HCWs) compliance with hand hygiene (HH).Settings. Medical and postoperative cardiac surgery units.Design. Prospective cohort study.Subject. The study included 40 HCWs.Intervention. Each HCW was interviewed on 3 separate occasions. The 1st interview was held to obtain a handprint culture before and after a session demonstrating the 7 steps of HH using alcohol-based hand rub, allowing comparison of results before and after HH. A 2nd interview was held 6 weeks later to obtain handprint culture after HH. A 3rd interview was held to obtain a handprint culture before HH. One month before implementation of handprint cultures and during the 12-week study period, monitoring of HCWs for compliance with HH was observed by 2 independent observers.Main Results. There was a significant improvement in HH compliance following handprint culture interview (p<0.001). The frequency of positive cultures, obtained from patients with suspected healthcare-associated infections, significantly declined (blood cultures:p=0.001; wound cultures:p= 0,003; sputum cultures:p=0.005).Conclusion. The visual message of handprint bacterial growth before and after HH seems an effective method to improve HH compliance.

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Sick leave before and after the age of 65 years among those in paid work in Sweden in 2000 or 2005: a register-based cohort study

Journal of International Medical Research ◽

10.1177/0300060517734744 ◽

2017 ◽

Vol 46 (2) ◽

pp. 564-577 ◽

Cited By ~ 2

Author(s):

Kristin Farrants ◽

Linnea Kjeldgård ◽

Staffan Marklund ◽

Jenny Head ◽

Kristina Alexanderson

Keyword(s):

Cohort Study ◽

Sick Leave ◽

Older People ◽

Older Workers ◽

Retirement Age ◽

Socioeconomic Differences ◽

Age Group ◽

Paid Work ◽

Before And After ◽

The Mean

Objective With pressure for older people to remain in work, research is needed on how people aged over 65 years fare in the labour market. However, few studies have focused on sick leave among older workers, especially those over the standard retirement age. This study investigated changes in sick-leave patterns among people aged over 65 years still in work. Methods All individuals in Sweden who turned 65 years old in 2000 or 2005 were followed from 1995 to 2010. The mean number of sick-leave days per year was measured for those who remained in paid work past the age of 65 years. Results Those over 65 years still working had fewer sick-leave days before the age of 65 years than those who retired. They also had fewer sick-leave days after 65 years than before. There were fewer socioeconomic differences after 65 years than before, but these differences were greater for workers over 65 years in the 2005 cohort. Conclusions Although there were more people over 65 years in paid work in 2005, sick-leave days and socioeconomic differences in sick leave were lower in this age group. Sick-leave days and socioeconomic differences in sick leave were greater in the 2005 cohort.

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Safety of Pfizer-BioNTech vaccine in a cohort of healthcare providers: differences between naïve and previously infected.

10.22541/au.162632854.49804314/v1 ◽

2021 ◽

Author(s):

ANDREA CHONG VALBUENA ◽

Isabel De-Jesus-Maria ◽

Adriana Agurto-Ramírez ◽

Francesc Puchades Gimeno ◽

Mercedes Melero-García

Keyword(s):

Cohort Study ◽

Adverse Events ◽

Retrospective Cohort ◽

Healthcare Workers ◽

Healthcare Providers ◽

Absolute Number ◽

Past Infection ◽

Spanish Society ◽

Relative Risks ◽

History Of

Introduction: The Spanish Society of Immunology recently warned that a history of past COVID-19 could result in a higher incidence of adverse events (AEs) related to vaccination. We set out to analyze whether there were any differences in AEs between healthcare workers vaccinated for COVID-19 (either after the first or second dose) who had had a prior diagnosis SARS-CoV-2 infection compared to those who had not had COVID-19 before vaccination. Methods: This was a retrospective cohort study in a population of healthcare workers. AEs related to the first and second doses of the Pfizer vaccine were recorded. We compared the incidence of AEs and compared individuals with 0–3 different AEs to those with 4 or more AEs. The relative risks (RR) and their 95% confidence intervals were calculated. Results: Past infection was associated with having more AEs after the first dose (p < 0.001), but not the second one (p = 0.476), as well as a higher incidence of AEs (p < 0.001). Common AEs that were statistically associated with past COVID infection included arthralgia, asthenia, fever, chills, headache, and myalgia (p ≤ 0.001). The RR for having an increased absolute number of different AEs was 1.18 (95%CI [1.05, 1.33]) after the first dose and 1.05 (95%CI [0.96, 1.14]) after the second dose. Conclusions: Our results showed that the incidence of AEs was higher in individuals with a history of prior COVID-19 infection.

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Screening for high amounts of SARS-CoV-2 identifies pre-symptomatic subjects among healthy healthcare workers

10.1101/2020.12.13.20248122 ◽

2020 ◽

Author(s):

Joakim Dillner ◽

K. Miriam Elfström ◽

Jonas Blomqvist ◽

Lars Engstrand ◽

Mathias Uhlén ◽

...

Keyword(s):

Logistic Regression ◽

Sick Leave ◽

Nucleic Acids ◽

Healthcare Workers ◽

Multinomial Logistic Regression ◽

University Hospital ◽

Symptomatic Disease ◽

Cycle Threshold ◽

The Past ◽

Increased Risk

AbstractBackgroundPre-symptomatic subjects are spreaders of SARS-CoV-2 infection, and strategies that could identify these subjects, particularly in hospital settings, are needed.MethodsWe tested a cohort of 9449 employees at work at the Karolinska University Hospital, Stockholm, Sweden for SARS-CoV-2 RNA and antibodies, linked the screening results to sick leave records and examined the association between screening results and past or future sick leave using multinomial logistic regression.ResultsWe found that healthcare workers with high amounts of SARS-CoV-2 virus, as indicated by the Cycle threshold (Ct) value in the PCR, had the highest risk for sick leave in the two weeks after testing (OR 11·97 (CI 95% 6·29-22·80)) whereas subjects with low amounts of virus had the highest risk for sick leave in the past three weeks before testing (OR 6·31 (4·38-9·08)). Only 2·5% of employees were SARS-CoV-2 positive while 10·5% were positive by serology and 1·2% were positive in both tests. Serology-positive subjects were not at excess risk for future sick leave (OR 1·06 (95% CI, 0·71-1·57)), but virus-positive subjects had a 7·23 fold (95% CI, 4·52-11·57)) increased risk for sick leave within two weeks post testing.ConclusionsScreening of asymptomatic healthcare workers for high amounts of SARS-CoV-2 virus using Ct values will identify pre-symptomatic subjects who will develop disease in the next few weeks. Identification of potentially contagious, pre-symptomatic subjects is likely critical for protecting patients and healthcare workers.Main pointHealthy healthcare workers with low amounts of SARS-CoV-2 nucleic acids will previously have had the disease. Presence of a high amount of SARS-CoV-2 nucleic acids predicts future symptomatic disease.

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