You might know of doctors advising patients to take the influenza vaccine every year. Have you ever wondered why doctors stress on the annual flu shot? The reason behind their advice is the constantly mutating viral genome. Sometimes flu viruses mutate on their own while multiplying and sometimes they directly swap genes with other viruses through recombination.
Mutation causes changes in the antigens on the surface of the virus, preventing their binding with immune receptors. With such a change, vaccines against the original virus also become ineffective. Considering the mutation of influenza virus, the vaccine against them is updated every year to include the latest influenza virus strains that might be dominant in the upcoming flu season.
Presently, the two dominant influenza A strains in circulation are the H1N1pdm09 virus and the H3N2 seasonal virus. However, recently new H3N2v swine flu virus has been found spreading rapidly. As told by the Centers for Disease Control and Prevention (CDC), till now, H3N2v has infected handful of people based in five states, namely Iowa, Indiana, Maine, Pennsylvania and West Virginia.
Experts believe that this new strain might be dangerous for children, as of 12 infected people, 11 were children. Vulnerability of children to the new virus can be explained by the token that they haven’t had exposure to H3N2 viruses. Scientists claim that the virus originated in pigs, but half of the reported cases had no contact with pigs, indicating higher chances of a person-to-person transmission.
In spite of the fact that till now, there have been no deaths and only mild symptoms, such as, fever, cough, nausea, vomiting and body aches, have been observed in patients, health officials can’t ignore the new virus. For the time being, it is hard to predict whether the new H3N2v strain will affect the flu season or not, but if it mutates into something more dangerous, things can go bad as the current vaccine will be ineffective.
After the 2009 swine flu pandemic, health experts can’t risk passing over any new flu strains. As a preparation for the future outbreak, scientists of CDC have already prepared a "seed virus". This virus can be used to develop a monovalent vaccine effective against new H3N2v, in case the need arises, but like 2009 that would be both expensive and inconvenient.
The present flu jab, which is actually a trivalent vaccine, protects against the three separate flu strains. Now, adding the H3N2v strain to the trivalent vaccine can be complicated. If researchers think of dropping one of the three current flu strains from the vaccine, it can pose serious public health ramifications. Hopefully, we won’t need a new vaccine, but with the H1N1 pandemic just three years ago, nothing can be taken for guaranteed.