Can the influenza vaccine help protect against flu attacks?

Question

Hi doctor,

My parents are admittedly in the hospital and were not keeping up with their annual vaccinations. Well, sure enough, my mother ended up catching the flu a few weeks back, and it has become very severe. She has a high fever and aches all over her body. She is an otherwise healthy 62-year-old, but this flu had her mattress-ridden for over a week. My father had to take her to the doctor because she got so dehydrated and weak. It was basically her worst-case flu scenario in life. My question is, how effective are we expecting this year's flu vaccines to be in protecting against whichever strain(s) are going around, especially for older adults? I know efficacy can vary year-to-year based on mutations and such factors. I am just wondering if my parents got lucky by skipping their shots this time or if the vaccine really could have prevented my mother's brutal bout with influenza. Please advise.

Thank you.

Answer 1

Hello,

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The effectiveness of the flu vaccine can vary from year to year depending on several factors, including the match between the vaccine strains and the circulating flu viruses, the age and health status of the vaccine recipient, and other factors such as immune response and vaccine coverage rates. Here is what we can generally expect for this year's flu vaccine effectiveness, particularly for older adults:

1. Vaccine Composition: Each year, the flu vaccine is updated to include strains of influenza viruses that are predicted to be the most likely to circulate during the upcoming flu season. The effectiveness of the vaccine depends on how well these selected strains match the viruses that actually end up circulating in the community.

2. Age-related Immune Response: Older adults, particularly those aged 65 and older, may have weaker immune responses to the flu vaccine compared to younger individuals. This can impact the effectiveness of the vaccine in preventing flu illness and complications in this age group.

3. Vaccine Coverage and Uptake: The effectiveness of the flu vaccine can also be influenced by vaccine coverage rates in the population. Higher vaccination rates can lead to greater community immunity and reduce the overall spread of flu viruses, thereby enhancing the vaccine's effectiveness for both vaccinated and unvaccinated individuals.

4. Antigenic Drift and Shift: The influenza virus can undergo antigenic drift (minor changes in viral surface proteins) and antigenic shift (major changes due to reassortment of different flu virus strains), which can impact the match between the vaccine strains and circulating viruses. These changes may affect vaccine effectiveness, particularly if new strains emerge or if existing strains undergo significant mutations.

It is difficult to determine with certainty whether your parents would have been protected from influenza if they had received the flu vaccine. The effectiveness of the flu vaccine can vary from year to year and depends on several factors, including the match between the vaccine strains and the circulating flu viruses, individual immune responses, and other factors such as vaccine coverage rates.

While the flu vaccine is not 100 percent effective at preventing flu illness, particularly in older adults who may have weaker immune responses, vaccination remains the best way to reduce the risk of flu infection and its complications. Even if someone still gets sick after receiving the flu vaccine, vaccination can help reduce the severity of illness, hospitalizations, and deaths associated with influenza.

It is also worth noting that the flu vaccine protects against multiple strains of influenza viruses, including both influenza A and B viruses, so even if one strain is predominant in a given season, the vaccine may still provide some protection against other circulating strains.

I hope that you get your answer.

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Thank you.