Influenza vaccine composition needs to be changed each year after evaluating the genetic composition of circulating Influenza virus strains at that time. Influenza viruses continuously evolve and vaccine needs to be “smarter” each year to provide effective immunity against flu. WHO recommends the revised ingredients of the Influenza virus vaccine each year, based on the observations and evaluations of the various laboratories worldwide. Scientists at the National Institute of Virology (NIV) in Pune, run by the Indian Council of Medical Research’s (ICMR), isolated a new strain called the Michigan strain circulating in Maharashtra during the H1N1 flu monitoring. According to Dr Soumya Swaminathan, director-general ICMR, old Influenza vaccine may be ineffective against the new strain of swine flu.
2017-18 recommendations by WHO for the trivalent Influenza vaccines to be used in northern hemisphere including India are:
- an A/Michigan/45/2015 (H1N1)pdm09-like virus;
- an A/Hong Kong/4801/2014 (H3N2)-like virus; and
- a B/Brisbane/60/2008-like virus.
The H1N1 (swine flu) pdm09 virus has been updated from California strain (or type) virus to Michigan strain (or type) virus. Other virus strains should remain the same as in last year vaccine concoction.
The new stocks of Influenza vaccine are likely to hit the Indian market by mid august or early September. Please get the vaccination done if you or your family member belong to high risk group as soon as the new vaccine is available. Children from 6 months to 9 years of age are susceptible to Influenza and can be given vaccine each year. Pregnant women should be given the vaccine in 2nd or 3 rd trimester as they are highly susceptible to serious flu infection. Vaccine will not only protect the mother-to-be but also her newborn baby later. Adults coming under high risk category are patients with Lung, Liver, Heart and Kidney disorders, Diabetes, hematological diseases, diseases that impair respiratory functions, and immunosuppression. Also, the personnel employed in nursing homes or health care facility and household contacts of children <5 years are recommended to take the yearly flu shots.