I Introduction to influenza Department of Health 2015 Vaccination Campaign Training workshop Presentation developed by the National Institute for Communicable Diseases ( Center for Respiratory Diseases and Meningitis and Division of Public Health Surveillance and Response ) Last updated: 06/ 02/ 2015

What is influenza? Runny nose Blocked nose Sore throat This is NOT necessarily influenza Many other viruses cause respiratory illness

Typical symptoms of flu Sudden onset of Fever Chills Cough Headache Muscle and joint pain Sore throat and runny nose Sometimes vomiting and diarrhoea

Severe disease >50% of hospitalised patients have underlying medical conditions Groups at increased risk Pregnant women Very young Elderly Immunocompromised and HIV infected Underlying medical conditions, such as heart or lung disease or diabetes Big contributor to mortality world-wide – 250,000 to 500,000 deaths every year.

Severe disease complications Pulmonary Pneumonia (primary influenza, secondary bacterial, and mixed) and bronchitis Exacerbation of asthma, chronic obstructive pulmonary disease (COPD), or other underlying lung disease Non-pulmonary Cardiac complications (myocarditis) Encephalopathy Liver and central nervous system (Reye’s Syndrome) Peripheral nervous system (Guillain-Barré syndrome)

What causes influenza? A virus transmitted from person-to-person by Direct transmission: coughing and sneezing (droplet) mucus directly into the eyes, nose or mouth of another person Airborne transmission: inhalation of aerosols produced by coughing and sneezing. Fomites: Contaminated surfaces or hands: Hand-to-eye, -nose, -mouth Three types: A, B and C A and B cause much more severe disease than C

What causes influenza? Enveloped virus 100nm Genome composed of 8 RNA strands The predominant surface protein is the haemagglutinin protein (HA) Responsible for binding to host cells and inducing neutralizing antibodies Neuraminidase protein (NA): Help the virus to be released from the host cell. Body mounts immune response against HA and NA

Influenza virus- Antigenic Drift HA and NA accumulate mutations Immune response no longer protects fully Leads to sporadic outbreaks, limited epidemics, and seasonal influenza activity

Influenza virus-Antigenic Shift “New” HA or NA proteins Pre-existing antibodies do not protect May lead to pandemics

Where do the “new” HA and NA come from? Influenza Virus Where do the “new” HA and NA come from? 13 types of HA and 9 types of NA, circulating in domestic and wild birds, pigs, humans and other animals

History of Influenza pandemics Name Date Deaths CFR% Subtype Asiatic (Russian flu) 1889-1890 1 million 0.15% H3N2 1918 flu pandemic 1918-1920 20 - 100 million 2% H1N1 Asian flu 1957-1958 1 - 1.5 million 0.13% H2N2 Hong Kong flu 1968-1969 0.75 – 1 million <0.1% 2009 flu pandemic 2009-2010 >18,000 0.03%

Influenza strains detected 1984 - 2014 Courtesy of the NICD’s Viral Watch Surveillance Programme

Influenza seasons 1984-2014 Mean onset: Mean peak: Mean duration: Week 22(1st week of June) Range 17-28 2014 2013 2012 2011 2010 2009 2008 2007 2006 Mean peak: Week 27(2nd week of July) Range 20-32 2005 2004 2003 2002 2001 2000 1999 1998 1997 1996 Mean duration: 12 weeks Range 7- 25 1995 1994 1993 1992 1991 1990 1989 1988 1987 1986 1985 1984 Courtesy of the NICD’s Viral Watch Surveillance Programme

Virologic Surveillance in South Africa, from 2009 H1N1 pandemic to present

Positive samples by influenza types and subtypes, South Africa 2015 ?

Influenza vaccines Each year, NICD sends data and strains to the World Health Organization (WHO). Together with info from other countries, WHO predicts the specific virus strains that will be circulating in the next year Formulation  pharmaceutical companies produce that vaccine (±6months) Due to high mutation rate, people need to be re-vaccinated each year Note: it is possible to still get influenza if vaccinated Not all strains covered (max 3 specific strains in vaccine) Vaccine takes 2 weeks to become effective. If infected during that time, you can still get flu

Recommended Vaccine Formulations for southern hemisphere, 2015 Trivalent vaccine an A/California/7/2009 (H1N1)pdm09-like virus an A/Switzerland / 9715293/2013(H3N2)-like virusa; a B/Phuket/3073/2013-like virus Vaccines should contain 15μg of each haemagglutinin antigen in each 0.5ml dose Protection derived from influenza vaccination lasts about 6 months a A/South Australia/55/2014, A/Norway/466/2014 and A/Stockholm/6/2014 are A/Switzerland/9715293/2013-like viruses

Thank you! Presentation developed by the Division of Public Health Surveillance and Response and Center for Respiratory Diseases and Meningitis, NICD-NHLS 18