Influenza Vaccines Helped Prevent 8,000 Deaths During Recent Influenza Season

Melissa Rolfes, PhD, MPH

The 2017-2018 influenza season has been an exceptional season – and not in a good way – with 79,000 influenza-related deaths and the highest number of influenza cases since the 2009 swine flu epidemic. , a new badysis from the Centers for Disease Control and Prevention indicates that the situation could have been much worse without the influenza vaccine.

According to the badysis, the influenza vaccine prevented 7.1 million illnesses, as well as 109,000 hospitalizations and 8,000 deaths. Hospitalizations were 10% lower than those expected without the vaccine and 41% lower for young children aged 6 months to 4 years. This is despite the fact that last year's influenza vaccine was only 38% effective.

"We hope that our results will help clinicians use when they talk to their patients about the possibility of being vaccinated against influenza and hope that these results will also encourage the general public to seek vaccination," he said. Melissa Rolfes, PhD. , MPH, epidemiologist in the CDC's influenza division and lead author of the study.

The CDC estimates that about 42% of the US population has received an influenza vaccine during the 2017-2018 influenza season.

"With our current vaccines, if more people were to be vaccinated, more people would be protected and the burden of influenza would be less," she said. "On the other hand, a better vaccine efficacy could generate greater protection. It is important to strike a balance between promoting the use of existing vaccines while looking for improved vaccines that could offer better protection. "

Strategies to improve the effectiveness of vaccines include increasing the dose of antigen in vaccines and researching methods of growing non-egg-based vaccines. The latter would be particularly useful with A (H3N2) viruses, said Rolfes.

"Most influenza vaccines are produced with viruses that spread in eggs. and influenza A (H3N2) viruses transmitted in eggs tend to adapt to changes that further and further distort the virus from the original A (H3N2) that had been placed in the body. egg, "she explained.

This can lead to more reactive vaccines against the version of the egg-based virus than against the actual version. She said that some commercially available vaccines are not egg-based, but there is still not enough data to know whether they outperform their egg-based counterparts, or whether benefits would continue to accrue. one year on the other.

Rolfes added that it is not too late for patients to be vaccinated against influenza – but this could have important public health benefits. Even if the vaccine's effectiveness is only 38%, for thousands of people each year, the vaccine or not could be a life-and-death decision.

"It's humbling and scary that thousands of people are hospitalized and die of influenza each year. It's not a mild infection and even healthy people can succumb to the flu, "she said.

The study "Effects of Influenza Vaccination in the United States during the 2017-2018 Influenza Season" was published in Clinical Infectious Diseases.