How effective is this year’s flu shot?Here’s When Will Know

How long will it take before we know if this year’s vaccinations are effective against the more prevalent strains of influenza, due to possible viral “mismatches”?

Unfortunately, it may still take months for experts to develop a better understanding.

In recent years, influenza vaccination has provided approximately 43% protection against disease. It fluctuates significantly from year to year, from 60% of the 2010-2011 flu season to 19% of the 2014-2015 flu season.

The number of flu cases has increased this year, but the peak of the season has not yet begun. And it won’t be until more people get sick that experts can identify the most common strains and see how they match up with the strains used for shots.

For example, until mid-December of the 2021 flu season researchers have discovered The vaccine strain and the circulating influenza virus were not a perfect match. says.

As the flu season progresses, data will be continuously collected to reveal the full picture. “Predictions for the 2022-23 flu season will continue to be updated for the rest of the year,” he said. After this, “the CDC will produce a report on the effectiveness of the vaccine.”

Experts say flu shots can also help reduce symptoms in those who eventually develop the disease.

Some think that looking at countries in the Southern Hemisphere with early flu seasons can give an indication of what the virus will look like when it arrives in the Northern Hemisphere.

for example, CDC pointed out In Chile, where the flu season began in January, the main strain circulating was a variant of the influenza A(H3N2) virus. resulted in more hospitalizations than

However, “the reliability of this approach is debatable.” Matt WeissenbachDrPH, Senior Director of Clinical Operations Walters Kluwer HealthShared with Healthline.

This is mainly because “confounding variables and limitations, such as missing data and external factors that could not be controlled” were not taken into account.

That said, Weissenbach continues, “It’s still a worthwhile exercise when looking at overall incidence, timing, and season length projections.”

As mentioned earlier, Chile’s flu season started earlier than usual. Weissenbach believes we may see a similar pattern in the United States.

“In some areas, we have already seen an increase in influenza transmission early in the season,” he said. “It is entirely possible that activity will continue to increase early in the season, as we have seen in many countries in the Southern Hemisphere.”

By the end of October 128.4 million US individuals were vaccinated against the 2022 influenza.

Vaccines target multiple types of influenza viruses. “All flu vaccines in the United States are ‘quadrivalent’ vaccines, which means they protect against four different influenza viruses,” Boden-Albala revealed.

She pointed out that the four viruses are:

• Influenza A(H1N1) virus
• Influenza A(H3N2) virus
• two influenza B viruses

It takes about two weeks after vaccination for protective antibodies to develop in the immune system, Boden-Albala said. However, these antibodies do not last forever. This is another reason why we recommend getting the flu shot every year.

Numerous studies have been conducted on how effectively influenza vaccines protect against the virus. CDC Estimate During the 2019-20 flu season, vaccination prevented approximately 7.5 million flu infections and 105,000 flu-related hospitalizations.

Meanwhile, in Chile earlier this year, vaccination related The risk of hospitalization due to A(H3N2) influenza virus was reduced by 49%.

The impact of the pandemic on immunity

Boden-Albala shared that epidemiologists are predicting that the next flu season could be “bad”. This is because

But is there another reason why more people might be affected? The aftermath of pandemic-related measures such as wearing masks, social distancing, and staying home.

“Community mitigation measures implemented throughout the pandemic are believed to have had some impact on transmission of the influenza virus,” said Weissenbach.

Further, Boden-Albala explains: [our] Exposure to influenza in the past few years. ‘ So, ‘it would be expected that the flu could get worse because of the low levels of circulating antibodies.’

the government said Anyone over the age of 6 months can be vaccinated against influenza, but in rare cases it is not recommended for some people (such as those with certain allergies).