Effectiveness of Flu Vaccination and Burden of Illness Among Community-dwelling Elderly With Influenza Like Illness in Brazil

• Number of days of illness since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Number of days of reduced activity since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Number of days off work of other family members or caregivers to provide patient care since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Number of medical visits related to influenza-like illness since Visit 1 [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Use of medication since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Occurrence of complications since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Hospitalization since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Presence of non-influenza respiratory pathogens in patients presenting with influenza-like illness defined as positivity by PCR [ Time Frame: At enrolment (day 0) ] [ Designated as safety issue: No ]
• Number of deaths [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Clinical features related to influenza-like illness [ Time Frame: At enrolment (day 0) ] [ Designated as safety issue: No ]

• Number of days of reduced activity since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Number of days off work of other family members or caregivers to provide patient care since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Number of medical visits related to influenza-like illness since Visit 1 [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Use of medication since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Occurrence of complications since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Hospitalization since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Presence of non-influenza respiratory pathogens in patients presenting with influenza-like illness defined as positivity by PCR [ Time Frame: At enrolment (day 0) ] [ Designated as safety issue: No ]
• Number of deaths [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]
• Clinical features related to influenza-like illness [ Time Frame: At enrolment (day 0) ] [ Designated as safety issue: No ]
• Number of days of illness since onset of influenza-like illness [ Time Frame: At the follow-up contact (between day 12 and 28) ] [ Designated as safety issue: No ]

The purpose of this research study is to estimate how many elderly people who have symptoms that look like influenza (i.e. an influenza-like illness) actually have the disease and how effective influenza vaccines are in preventing influenza in elderly people. The study will also examine the severity of the disease (e.g. how long are people ill, were there any complications) and how it affects everyday life (e.g. cost, medications, care by family members).

Adults aged 65 years and over, consulting a physician for an influenza-like illness during the influenza season.

• Influenza
• Insufficient Information

Inclusion Criteria:

• Subjects who the investigator believes that they can and will comply with the requirements of the protocol.
• A male or female >= 65 years of age.
• Written informed consent obtained from the subject.

• Presenting within the first 72 hours of an influenza-like illness. Influenza-like illness is defined as the presence of:

  • Fever measured by the patient or physician and at least one of the following symptoms:
  • Sore throat.
  • Coryza (runny nose) and/or nasal congestion.
  • Cough.
• Availability to be followed up by phone or in person after an interval of approximately 14 - 21 days.

Exclusion Criteria:

• Receipt of any experimental influenza vaccine within 6 months of the onset of the influenza-like illness.
• Terminal stage of disease.
• Subjects living in a nursing home.
• Use of any investigational or non-registered product planned during the study period.
• Subjects who have already been enrolled in this study.