As a consequence, the Centers for Disease Control and Prevention (CDC) urge all people at high risk of influenza related complications to seek treatment as early as possible if any symptoms of flu are recognized.
“Doctors ought to be aware that all hospitalized patients and all outpatients at high risk for severe complications must be treated at the earliest opportunity with one of three available flu antiviral medications if flu is suspected, in spite of a patient’s vaccination status and without holding up for confirmatory testing,” says Dr. Joseph Bresee, branch head of the Influenza Division at the CDC.
“Health care experts ought to exhort patients at high risk to call promptly if they get symptoms of flu,” he adds.
The CDC arrived at their assessment, published in the week’s Morbidity and Mortality Weekly Report (MMWR), by examining 2,321 children and grown-ups with severe respiratory sickness.
Of these, 950 (41%) had the flu virus, with 916 (96%) testing positive for flu A – all of which were H3n2 viruses – and 35 (4%) testing positive for flu B. The 2014-15 influenza vaccine was found to have been administered to 49% of patients with flu and 56% of patients without the virus.
From this, the CDC estimates that influenza vaccine has diminished an individual’s risk of visiting a specialist because of influenza by 23%. This result stayed after bookkeeping for patients’ age, sex, race/ethnicity, self-reported health and the number of days between sickness onset and study enlistment.
Vaccine efficacy against H3n2 viruses was assessed to be highest among kids and teenagers aged 6 months to 17 years, at 26%. Vaccine efficacy was lower among grown-ups aged 18-49 and 50 and over, at 12% and 14%, correspondingly.
The report authors say their results demonstrate the efficacy of this season’s vaccine is comparatively low, contrasted with some seasons where vaccine efficacy has arrived at 50-60%.
70% of this season’s H3N2 viruses are ‘drift variants,’ making flu vaccine less effective
The CDC say their evaluation supports past discoveries that the 2014-15 influenza vaccine has low efficacy against circulating flu A H3n2 viruses, which, as the report demonstrates, have been the most major viruses this season.
H3n2 viruses are the most serious, bringing about the most elevated number of hospitalizations and deaths. Amid the three seasons with the most elevated death rates in the course of recent years – 2012-13, 2007-08 and 2003-04 – H3n2 viruses were the most widespread.
The CDC note that around 70% of this season’s H3n2 viruses have been recognized as “drift variants” – viruses that have antigenic or genetic changes that make them unique in relation to the virus included in this season’s influenza vaccine, implying the vaccine efficacy is decreased.
Vaccine efficacy, the CDC says, is also reliant on the age and health of the individual getting the vaccine; it tends to be most effective in young, healthy individuals and less effective among older ones – as showed in the report’s estimations.
Findings should not deter from vaccination
Regardless of the low efficacy of the 2014-15 influenza vaccine, the CDC keep on suggesting that all individuals aged 6 months and older get the vaccine, as it may still impede infections from some circulating flu A H3n2 viruses and diminish acute influenza related complications.
“Additionally, vaccine may ensure against other flu viruses that can circulate later,” the report authors said. “Since early November, 2014, less than half of US occupants had reported getting flu vaccine this season. Flu vaccine, even when efficacy is decreased, can avert thousands of hospitalizations.”
Additionally, the CDC say their estimation stresses the importance of extra prevention and treatment measures against flu – especially for people aged 65 and older, young children and others at high risk of influenza related complications.
The report authors write:
“Flu antiviral medications ought to be utilized as suggested for treatment in patients, despite of their vaccination status. Antiviral treatment can diminish the term of ailment and lessen complications connected with flu.
Antiviral treatment ought to be utilized for any patient with suspected or affirmed flu who is hospitalized, has serious or progressive sickness, or is at high risk for complications from flu, regardless of the possibility that the disease appears mild.”
They include that antiviral treatment ought to be administered in 48 hours of influenza symptoms presenting, yet it can still be effective among some patients even if initiated after this time.
The need for more effective influenza vaccines
The report authors say that while influenza vaccines are the best assurance we have against flu at present, there is a need for more effectual ones, and this is something that may soon be on the cards as indicated by another study reported by MNT today.
