The effectiveness of seasonal influenza vaccine against h3n2 influenza …

H3N2 VIRUS is a non-human influenza virus that normally circulates in pigs and that has infected humans.Influenza A (H3N3) is responsible for present rise in flu cases as notified by ICMR. Both H1N1 and H3N2 sub-types are variants if influenza A which change genetically as well as antigenically to produce new variants. H3N2 tends to change more rapidly, both genetically and antigenically, compared to H1N1. H3N2 is the cause behind rise in flu case that we have been seeing recently.

Influenza ( H3N2) pandemic was first reported in 1968 in the USA for the first time and recently in the year 2011 and again 2020-21.Influenza viruses can spread from pigs to people and from people to pigs. Spread from infected pigs to humans is thought to happen in the same way that seasonal influenza viruses spread between people; mainly through infected droplets created when an infected pig coughs or sneezes.

The symptoms of H3N2 virus are similar to other respiratory viruses, including fever, sore throat, nasal discharge, headache, coughing, myalgia, and nasal discharge. In severe cases, pneumonia and bronchitis could happen, which can lead to death.

As we know that there is no targeted therapy for most of the viral infections and specially for flu it is symptomatic therapy that is advised for patients. Oral anti virals like osaltamavir , zanamivir, peramivir can be used . Preventive measures like using masks, frequent hand wash, cough etiquette and self isolation are recommended to minimise the risk of disease transmission to other members in the community.

There is no specific vaccine for h3n2 variant of influenza A virus but research to develop a vaccine has started. A pilot H3N2 virus vaccine was produced and preliminary clinical studies indicated that it leads to a significant immune response.Seasonal flu vaccine will not protect against H3N2v. Seasonal flu vaccines protect against seasonal influenza viruses. CDC recommends that everyone 6 months and older get a seasonal flu vaccine each year. Many types of seasonal influenza vaccines are available in the market and a new strain vaccine is produced every year according to the change that happens due to antigenic drift in the virus.

Vaccines are advised and are helpful in preventing serious form of the illness. Influenza vaccines, though, generally have variable and only moderate efficacy; they remain a critical preventive strategy for controlling the disease and its consequences. The egg-based quadrivalent vaccines have been recommended as they give protection to both influenza A and B variants.

In the case of influenza, effectiveness is expected to be lower than the efficacy ( reduction in risk of a disease in a given condition )because it is measured using the rates of influenza-like illness, which is not always caused by influenza. Studies on the effectiveness of flu vaccines in the real world are difficult due to many reasons vaccines and also because influenza is often confused with other influenza-like illnesses. However, most of the times the flu vaccine strains have been a good match for the circulating strains and even a mismatched vaccine can often provide cross-protection.

The effectiveness of seasonal flu vaccines varies significantly, with an estimated average efficacy of 50-60% against symptomatic disease, depending on vaccine strain, age, prior immunity, and immune function.

Though vaccinated people can still contract influenza, The effectiveness of flu vaccines particularly among the elderly and immunocompromised is still beneficial in reducing the mortality rate and hospitalization rate due to influenza as well as duration of hospitalization stay. Vaccination of school-age children has shown to provide indirect protection for other age groups as well.

Considering the point that seasonal flu vaccine reduced chances of serious illness and complication leading to hospitalization and even death in certain cases it is advised to take a flu shot. Especially immunocompromised and elderly people above 65 years are recommended to take the vaccine annually.

Views expressed above are the author's own.

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The effectiveness of seasonal influenza vaccine against h3n2 influenza ...