COVID-19 antibodies testing among healthcare workers to evaluate the role of Covid 19Ab testing as screening method for detection of covid 19 infections among laboratory health care workers ,assess the relationship between the infection with Covid 19 and different laboratory categories/area and assessemt of efficiency personal protective equipment (PPE) in different laboratory categories/area.

In December 2019, a new corona virus (CoV) emerged in China to cause an acute respiratory disease known as corona virus disease 19 (COVID-19).The virus was identified to be a betacoronavirus related to severe acute respiratory syndrome corona virus (SARS-CoV) and thus, was named SARS-CoV-2 .

New Covid-19 virus is the third known corona virus to cross the species barrier and cause severe respiratory infections in humans following SARS-CoV in 2003 and Middle East respiratory syndrome in 2012, yet with pandemic spread compared to the earlier two. In comparison, to SARS-CoV and MERS-CoV, COVID-19 virus exhibits faster human-to-human transmission.

The World Health Organization (WHO) declared COVID-19 outbreak as a world pandemic on 12th March 2020. Diagnosis of suspected cases is confirmed by molecular techniques (real-time PCR), using respiratory samples. Serology tests are easier to perform than molecular testing, but their utility may be limited by the performance and the fact that antibodies appear later during the disease course.

In the absence of a vaccine, public health authorities in several countries has shown that shutdowns can only be safely ended if a systematic "test and trace" program is put in place to control the spread of the virus which depends on the widespread availability of mass diagnostic testing.

From this point of view, detecting carriers of the virus in asymptomatic laboratory health care worker is fundamental to response efforts. It ensures the quarantine of COVID-19 patients to prevent local spread and more broadly informs national response measures.

The main route of transmission is person-to-person spread. A vulnerable cohort for infection due to frequent and close contact to COVID-19 patients are healthcare workers. To avoid patient-to-staff transmission adherence to strict hygiene standards is important. The infection with the SARS-CoV-2 usually leads to seroconversion 11-14 days after the first symptoms . However, due to asymptomatic and oligosymptomatic infections testing only symptomatic individuals can lead to a significant underestimation of the SARS-CoV-2 seroprevalence Day,.

Antibody testing is multipurpose: these serological assays are of critical importance to determine seroprevalence, previous exposure and identify highly reactive human donors for the generation of convalescent serum as therapeutic. They will support contact tracing and screening of health care workers to identify those who are already immune. How many people really got infected, in how many did the virus escape the PCR diagnosis, and for what reasons, how many patients are asymptomatic, and what is the real mortality rate in a defined population? Only with comprehensive serology testing (and well-planned epidemiological studies) will we be able to answer these questions and reduce the ubiquitous undisclosed number in the current calculations. Several investigations are already underway in a wide variety of locations worldwide

Inclusion Criteria:

• • Covid 19 infected healthcare workers.

Exclusion Criteria:

• •Risky healthcare workers (diabetic, hypertensive and more than 50 years)

the study was carried out using EPI info 2000 statistical package and based on a CDC COVID-19 Response Team report where the prevalence of COVID 19 infected health care workers (CDC, 2020) The minimum calculated sample was 250 health care worker , with confidence interval 80%.