Dr. Kevin Most: Flu Season

Steve Cochran

Dr. Kevin Most

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For the first time in a long time the CDC is recommending that we all get vaccinated for the influenza virus before the end of October. I have always felt that the first week in November was a key date. We know it takes 2-3 weeks for our body’s immune system to build up the coverage needed for protection from exposure. We also know that historically the influenza season will start in November or December, so being vaccinated in late October or early November is key to protecting you as well as those around you.

So what is occurring this year that raises the concern for the early flu shot? Well as you know we look to the Southern hemisphere as an indicator to how our flu season may go, as their flu season goes thru our spring, summer and ends in the fall, we look to see what type of flu season they are having. With the information they send us, we can see how the vaccine that is being made thru the spring and summer here lines up with what they are seeing, and we see how strong their flu season was. Well this past season was a bad flu season in the Southern Hemisphere and worse than that, it started early. Take that information and see that the most prevalent strain was a very powerful Type A H3N2 strain and it was a perfect storm for them. This information was concerning enough and with the first death in the US from influenza to have already occurred is also a cause for alarm. There was a death of a 4 yo in California from influenza last week. This information also impacted the production of vaccine here in the United States.

Did we learn anything this past year from the Southern hemisphere flu season about the vaccine? Remember the WHO and CDC decide in mid to late February what should be in the annual vaccine for the next year, this is based on the previous year’s activity, the activity in the southern hemisphere and any changes or mutations that they noted thru the season. Because of the unique season last year, they postponed making their decision by over a month on what the final composition would be. The final decision was made in late March. It is felt with the current technology that production should not be hampered and that we will still see 170 million doses of the vaccine available for the US.

A few things other things can make this a bad season. One is the strain that hit the Southern hemisphere was one that impacted seniors and young children hard, The Type A H3N2 is and was a nasty virus. In seniors it will run rampant thru nursing homes an assisted living facilities where we have seniors together. It is one strain that often will end up in the lungs, most influenza viruses are content to hang out and wreak havoc in the upper respiratory system with few going on to pneumonia, H3N2 do not follow that pattern and are more able to get into the lungs. The second reason is that H3N2 viruses first showed up in the late 60’s, so that means that those over the age of 50 had the basis of their response to influenza actually set by other viruses. So those individuals in their 70s and 80s can fight off other influenza viruses better than they can H3N2. Individuals born after 1968 had early exposure to H3N2 and thus have an immune system that is able to respond to this virus better.

Many individuals feel that the tracking is so good that they will know when it is time to get the vaccine as they see cases being reported in their area. There are two things to remember , one is the time for the vaccine to work and two is the reporting will lag about a week as the report is done one day a week. So, the strategy to wait for the vaccine until activity is not a good plan.

If you remember the flu season in 2017-2018 was a terrible flu season with 80,000 deaths and over a million hospitalizations. The 2018-2019 season had its unique characteristics, it began a bit early in late October, and increased thru November. It peaked in mid-February , and did not go back to baseline until mid-April. We continued to see cases thru June. It was one of the longest flu seasons on record. It was felt to contribute to close to 50,000 deaths, which is down from the previous year, however we saw close to 45 million cases of influenza over the last flu season. When reviewed as to why it lasted so long, it had a few unique patterns where we saw a strain of Influenza A go from October until February and then a second wave of a different strain of Influenza A hit from February until June. That allowed for some people to actually get hit twice with influenza if they did not get vaccinated. We also saw some strong strains, and with a strong economy we saw a lot of travel, both domestically and internationally. We cannot minimize the impact travel has on the spread of an illness. The hospitalization and death rate was lower than the previous season.

So who needs a flu shot, essentially everyone over the age of 6 months. There is no vaccine for children under 6 months so special care must be given to infants that young to protect them from influenza. Many may think, that pregnant or those who have chronic illness should not get a flu shot and it is just the opposite, women who are pregnant should definitely receive the vaccine to protect themselves as well as their baby. It really comes down to the only individuals who should not get the vaccine are those with allergies to some component in the vaccine. Individuals with egg allergies should make sure the vaccine they receive is cell based and not egg based. No nasal spray vaccine for those under 2 yrs. old or over 50 yrs. old. Individuals who have compromised immune systems should discuss which vaccine is best for them.

This year seniors should be making sure they are immunized before the season starts, research completed last year showed that not only will influenza infection put them at risk for a serious if not deadly infection, but it will also put them at an increased risk for heart attack or stroke following the infection. This study was published in the NEJM last January. This is just another reason seniors should consider getting the flu shot, it appears it will protect you from influenza and lower your risk of heart attack and stroke thru that time as well.

This year we will see the vaccine in a few different strengths and delivery models. The nasal vaccine has been approved and will be available for healthy individuals between age 2 and 49, It again is not approved for women who are pregnant. The Flu Mist may be in short supply due to some manufacturing constraints. The overall number of vaccines should be sufficient, however anyone requiring or desiring the nasal vaccine Flu Mist should get it early as there will be a shortage of this vaccine. This hurts the reputation of the vaccine, as you may remember it was not approved for 2 full flu seasons from 2016-2018 due to the lack of effectiveness of the vaccine. The effectiveness was corrected and is now thought to be of equal efficacy when compared to the shot.

Vaccines for this year again contain protection for either 3 or 4 strains of influenza virus depending on the vaccine you choose. Again this year the High Dose vaccine will be available and is recommended for Seniors over the age of 65. As we age our immune system is not as responsive and exposing the individual to a higher dose allow for better chance of a response. This vaccine has been found to be just as safe as the other vaccines and thus should be promoted for the senior patients. The vaccine is being made by 4 different companies which helps as the delay this year in the composition has slowed the production and delivery of vaccine.

Do we have any disadvantage living in a urban suburban area? One may think, No the flu season is the flu season. A recent study looked at flu cases for over 600 zip codes, it showed that flu cases in less populated areas lasted a shorter time and the surge was more intense when corrected for population. Larger cities saw a much longer duration of flu activity, which allowed exposure opportunities to continue. What that tells health officials is that smaller towns should be preparing for surge capacity where larger towns should be more concerned about limiting spread and exposure.

Do we know how bad the flu will be this year? No but experts are concerned as we have already seen a death in California from influenza in a 4 yo infant. The concern is that many will take a pass and decide not to get vaccinated, as they feel last years shot was not helpful. This is the absolute wrong thing to do. We need to get higher vaccination rates. Remember even if the vaccine is not a perfect match you do get some protection and your immune system will make the episode lighter. The timing for the vaccine is now, get it before the end of October. It takes 2 weeks for the vaccine to be at full strength in your body, so getting it after you have had a direct exposure is not going to help. The goal is to be vaccinated well before we see the first outbreak. With the amount of travel we see at Thanksgiving everyone feels that having as many people vaccinated weeks before Thanksgiving is the best.

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