The study is a multi-center, prospective, observational clinical study enrolling patients from at least 3 medical centers. Study population will include patients over the age of 18 years.

The study will recruit patients presenting with suspicion of acute infection/sepsis and healthy individuals.

Study main objective is to derive and verify a host response based score to predicte severe outcome.

For determining disease severity each enrolled patient will be assigned as either "severe outcome patient" or "non severe outcome patient" according to predefined criteria. (or "healthy").

Participation in the study requires the collection of routine patient data and blood sample. Blood samples will be used for measurements of host biomarkers that predict disease severity. The blood samples will be collected upon enrollment.

In addition, a standardized patient questionnaire inquiring about severity outcomes met up to 28 days after presentation will be conducted by phone call 28 to 42 days post admission.

Enrolled patients will be managed according to the current standard of care per standard institutional procedures. Results of the measured biomarkers will not be revealed to the attending clinician and so will not influence patient management.

Suspected acute infection/sepsis patients

Patients eligible for inclusion are required to fulfill all of the following criteria:

• Written informed consent must be obtained from the patient or his/her legal guardian.
• Over 18 years of age
• Clinical suspicion of acute infection/sepsis as defined by the attending physician, based on clinical presentation.

Healthy individuals

Patients eligible for inclusion are required to fulfill all of the following criteria:

• Written informed consent must be obtained from the patient
• Over 18 years of age
• No clinical suspicion of acute infection.

Exclusion Criteria:

Suspected acute infection/sepsis patients

Patients fulfilling the following criteria are not eligible for inclusion in this study:

• HIV, HBV, active HCV or active Tuberculosis infection (self-declared or known from medical records).
• Pregnancy- self reported or medically confirmed. Healthy individuals

Patients fulfilling the following criteria are not eligible for inclusion in this study:

• Episode of infection in the last 2 weeks
• Major trauma and\or burns and\or surgery in the last 2 weeks
• HIV, HBV, active HCV or active Tuberculosis infection (self-declared or known from medical records)
• Elective surgery patients
• Pregnancy- self reported or medically confirmed

patients presenting with suspected infection/sepsis as defined by the attending physician, based on clinical presentation and laboratory/radiological findings. Additionally, the study will recruit healthy individuals across all study sites.