Archive for August, 2010

A special flu vaccine for seniors

Friday, August 20th, 2010

Influenza vaccine works quite well in young adults. On average, it is 70% to 90% protective in that population. The range is quite wide because each influenza season is different, and some years the virus and the vaccine do not match each other as well as in other years.

In people over about the age of 65, however, the vaccine protection starts to drop. As we get older, our immune system does not respond to new challenges as well as when we were young. It still responds; just not as well. Scientists have studied ways to get the immune system of seniors to respond to vaccines better. We have tried giving multiple doses, adding an immune stimulator called an adjuvant to the vaccine, and increasing the dose of the vaccine. A new high-dose flu vaccine for seniors is available this season, and it works.

The high-dose vaccine contains four times more vaccine per dose than the standard vaccine. It is approved by the FDA for people over 65. It is recommended by the CDC, although the standard vaccine is also approved by the FDA and acceptable for this population.

The high dose vaccine was tested in 2575 seniors in a large trial, and it produced significantly better immunity than the standard dose. Because the high-dose vaccine is new and has obviously not been used against the 2010-11 influenza viruses, we will not know how well it will perform this year until the season is over and we can compare the numbers.

I think it is great that we have a vaccine that is tailored to this specific population rather than giving the same vaccine to everyone. The regular vaccine still works, and I still recommend it, but if you are over 65 and can get the high-dose vaccine, I would get it.

WHO: “The H1N1 pandemic is over”

Monday, August 16th, 2010

Last week the World Health Organization declared that the H1N1 influenza pandemic was over. The technical term they used to describe the situation is “post-pandemic period.” Interestingly, the US Centers for Disease Control and Prevention (CDC) announced the same week that this year’s flu season had already begun. How can both groups be right, and who should we believe?

They are both right. Let me explain. A pandemic is a statistically-significant increase in the number of cases of a disease worldwide or across more than one continent. The term “post-pandemic” means that the disease has returned to the level normally seen for influenza at that time and place. It doesn’t mean the virus went completely away. H1N1 is still around. It has just receded into the background or normal level of influenza we see every year, so the WHO is right.

Wasn’t the WHO announcement late? Yes, the H1N1 epidemic was probably over in the US several months ago. But remember that the WHO looks at the whole world, not just the US, and they have to wait and watch for a while after a pandemic is over to make sure it is not going to return, so this announcement looks to us in the US like old news.

So why did the CDC just say that flu is back? Summer is usually off-season for influenza in the US and other countries in the Northern hemisphere. The number of cases is low, but it still occurs. It can occur when groups of people get together, like at summer residential and sports camps. There have been clusters of cases reported already this summer, and the strain of flu we are seeing now is not H1N1 from last year, it is a new strain called H3N2.

Is this new H3N2 virus going to cause a pandemic like the H1N1 virus of 2009? No one knows, but I would guess not. Remember that we had no vaccine against H1N1 when it first came out, so the virus got ahead of us. The new H3N2 is covered by this year’s flu vaccine, so when we start immunizing people over the next month, we will be ahead of the virus.

One flu vaccine this year

Wednesday, August 4th, 2010

Last year (2009) was an unusual year for influenza for several reasons. Mostly because we needed two different vaccines. The normal flu vaccine contains three strains of virus and is designed to protect us from all the strains of the virus we are likely to encounter that year. Nature fooled us last year. A new virus strain, type H1N1, emerged and spread around the world after our regular vaccine was already in production. We made a new vaccine just for H1N1 and gave it after we gave the regular vaccine. Results showed that the H1N1 vaccine was a very good one, and probably prevented a lot of death and disease last year.

This year the new H1N1 strain is included in the regular vaccine, so we don’t need two vaccines. One vaccine will do the job. Even if a new strain emerged now, it is too late to make another vaccine this year anyway.

Some may think that if they took the H1N1 vaccine last year, they don’t need this year’s vaccine, but that is not true. The other two strains of flu will be coming back, and we need protection against all three, not just H1N1.

If you are a Bronson patient and want to make an appointment to get your flu immunization, we have an online registration system or call your doctor’s office. Vaccine is arriving at doctor’s offices and clinics in August, so it is not too early to make your appointment.