I Introduction to influenza Department of Health 2016 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: 13/ 01/ 2016

Influenza burden Acute viral infection of respiratory tract Causes significant morbidity and mortality – 3-5 million cases and ± deaths 1 – Burden greater in Africa 2,3 – In South Africa, ~ individuals ≥ 5 years (rate 21.6 per person years) die each year ~500 children <5 years (8 per person-years) die each year 4 – Burden of influenza associated hospitalisation and death can vary from year to year depending on transmission and virulence of the strain 1 Seasonal influenza, WHO ; 2 Cohen et al, 2005; 3 Nair et al, 4 Tempia et al

Influenza viruses Three types Influenza A viruses – Cause outbreaks most years – Usual cause of epidemics – Animal reservoir- wildfowl and some animals Influenza B viruses – Cause less severe disease and smaller outbreaks – Burden mostly in children – Cause severe disease in immunocompromised individuals – Predominantly found in humans Influenza C viruses – Minor respiratory illness only

Influenza A virus Enveloped virus 100nm Genome composed of 8 RNA strands The predominant surface protein is the haemagglutinin protein (HA) – Binds to host cells and induces neutralizing antibodies Neuraminidase protein (NA): – Help the virus to be released from the host cell – 18 types of H and 11 types of N Body mounts immune response against HA and NA

Influenza Virus Where do the “new” HA and NA come from? – 18 types of HA and 11 types of NA, circulating in domestic and wild birds, pigs, humans and other animals

Features of influenza 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 Incubation period 1-4 days (average 2 days) – May be longer Highly infectious, spreads rapidly Individuals with mild symptoms can still infect others

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- 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)

History of Influenza pandemics NameDateDeathsCFR%Subtype Asiatic (Russian flu) million0.15%H3N flu pandemic million2%H1N1 Asian flu million0.13%H2N2 Hong Kong flu – 1 million<0.1%H3N flu pandemic >18, %H1N1

Mean onset: Week 22(1 st week of June) Range Mean peak: Week 27(2 nd week of July) Range Mean duration: 13 weeks Range Influenza seasons, South Africa

Number of positive samples by influenza types and subtypes and detection rate* by week: Viral Watch 2015 Detection rate not calculated for <10 specimens per week

Positive samples by influenza types and subtypes, South Africa 2016 ?

Influenza vaccines NICD sends data and strains to the World Health Organization (WHO) annually WHO predicts the specific virus strains that will be circulating in the next year Formulation  pharmaceutical companies produce that vaccine ( ±6 months) Due to high mutation rate, vaccination needed each year 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 Flu vaccines DO NOT protect against infection and illness caused by other viruses.

Recommended Vaccine Formulations for southern hemisphere, 2016 Trivalent vaccine – an A/California/7/2009 (H1N1)pdm09-like virus – an A/Hong Kong/4801/2014 (H3N2)-like virus – a B/Brisbane/60/2008-like virus Vaccines should contain 15μg of each haemagglutinin antigen in each 0.5ml dose Protection derived from influenza vaccination lasts about 6 months

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