Mains Paper 2: Governance | Issues relating to development and management of Social Sector/Services relating to Health, Education, Human Resources.
The following things are important from UPSC perspective:
Prelims Level: Influenza Strain Types, H#N# Subtypes
Mains level: Read the attached story
Quadrivalent vaccine approved
- Sanofi Pasteur’s injectable influenza vaccine (FluQuadri) containing two A virus strains — H1N1 and H3N2 — and two B virus strains — Victoria and Yamagata — for active immunisation of adults of age 18 to 64 years was approved in May last year by the Drug Controller General of India (DCGI).
- The application for the paediatric indication is under review by the DCGI and final approval is expected by the end of this month.
- Sanofi’s quadrivalent influenza vaccine was licensed for use by the U.S. Food and Drug Administration (FDA) in 2013; it is licensed in 26 countries.
Why Quadrivalent vaccine?
- While a trivalent influenza vaccine contains both A subtype viruses, it has only one of the B subtype virus, the quadrivalent vaccine offers a greater breadth of protection as it includes both B subtype viruses.
- It is because of a greater breadth of protection that a few other companies too have shifted from a trivalent to a quadrivalent vaccine.
- Since the vast majority of influenza vaccines manufactured were trivalent till recently, the World Health Organisation (WHO) used to recommend two A subtypes and one B subtype, plus an optional fourth strain (the other B virus strain).
Benefits of Quadrivalent Vaccine
- The quadrivalent vaccine will contain four influenza virus strains (two A subtypes and two B subtypes — H1N1 and H3N2, and Victoria and Yamagata respectively).
- The viruses used in the vaccine are killed and this eliminates the possibility of the virus in the vaccine itself causing infection.
- In India, the vaccine will be available as a single dose pre-filled syringe
- Eventually, it will be available in a vial for public health use.
Incidences of different Strains
- In the case of H1N1, there are two strains — California and Michigan — that cause influenza. In India, the Michigan strain was earlier circulating and has been replaced by the California strain.
- For 2018, the WHO has recommended the Michigan strain for the southern hemisphere, including India.
- Each year, the vaccine changes to reflect the different strains in circulation.
- Year-round, scientists across the globe track, analyze and classify the viral strains causing illness.
- Despite the high number of infections and mortality each year, India does not have in place a national policy for influenza immunization.
- Pregnant mothers, children aged below five and young people with asthma, cardiovascular disease, diabetes and high blood pressure are at a greater risk of infection and death.
- The Ministry of Health issues only H1N1 vaccination guidelines for different vulnerable groups including healthcare workers.
- If we want to reduce the influenza burden in adults, then we must target children as they act as reservoirs.
Influenza is a virus that actually has hundreds of different strains. The virus mutates frequently, but the strains are classified into one of three main categories—A, B, or C.
Influenza A is the group that most commonly causes illness in humans.
- All influenza A viruses are further broken down into H and N subtypes. So, any influenza virus that is described as “H#N#” (such as H1N1) is an influenza A virus.
- There are 16 H subtypes and nine N subtypes, but only three combinations have actually caused highly contagious illness in humans.
- Other combinations have been found to infect other species (such as birds and pigs), but they have not caused widespread human infections.
- The three combinations that cause almost all outbreaks of the flu in humans are H1N1, H2N2 and H3N2.
- Even in these subtypes, the influenza virus can mutate and change each year. For this reason, influenza viruses are also named using:
- The host of origin (swine, chicken, etc., or no host if it is of human origin)
- The geographical location of origin (Hong Kong, Alberta, etc.)
- Strain number
- Year of discovery (or isolation)
- Influenza B is less common but still causes outbreaks of seasonal flu.
- One or two strains of influenza B are included in the seasonal flu vaccine every year to protect people from the strain(s) that researchers believe are most likely to cause illness during the upcoming flu season.
- The quadrivalent flu vaccine contains two strains of influenza B but the traditional trivalent flu vaccine only contains one.
- Influenza B is not broken down into subtypes like influenza A is, but it is broken down into individual strains.
- Typically, two strains of influenza A and one strain of influenza B are included in the seasonal flu vaccine. Quadrivalent flu vaccines contain two strains of influenza A and two strains of influenza B.
- Influenza B can cause outbreaks of seasonal flu but they occur less frequently than outbreaks of influenza A.