Tonight I am going to post as a follow-on to one of FM's posts today [here]. Although he did an excellent job of bringing the issue before us, I have a bit more to say on the subject. Vaccines and vaccination are an integral part of pandemic considerations and plans so they are subjects that are somewhat “near and dear” to my heart. But first a bit of a digression.
I believe in vaccines in general, believing they are of immeasurable benefit to a population as a whole, and to the individuals who receive them.
Are they effective for 100% of those who receive one? No. The immune response a vaccine produces can, and does, vary by individual, and cohort generalities exist. The article that inspired this post is about the weak immune response in frail elderly folk who receive a vaccination against influenza. The very young (who generally have not had influenza) also produce a weaker immune response, that is why their shot is delivered in two doses separated by a month. The first shot “primes” the immune system, the second produces antibodies at a presumptive level of protection.
Are they 100% safe and free of side effects for 100% of those who receive one? No. Nothing in this world is safe for every single person drawing breath. The level of risk – on average – for each individual receiving a vaccine is directly correlated with the length of time the vaccine has been given and the number of people who have received it. The ancillary: The longer a vaccine has been available and the greater number of people having received it might well find those 1-in-100 million who will have a meaningful adverse reaction.
Do they prevent the scourges of past generations? Yes. Have they enhanced quality of life and extended life expectancy? Yes – on both counts. Proof of these statements are the fact that I grew up without having to face the threat of polio or smallpox, and my son never had mumps or chickenpox.
Please feel free to skip the references, I've only included them in the interest of thoroughness.
On to today's news item…
Flu Vaccine Doesn't Protect Seniors From Pneumonia
Older, frail folks are more susceptible to flu and its complications, researchers say.
By Steven Reinberg
THURSDAY, July 31 (HealthDay News) -- Flu vaccine may not protect older people from pneumonia once they get the disease, researchers report.
Older, frail adults are more susceptible to getting the flu, even if they have been vaccinated, and once getting the flu, they are more susceptible to such complications as pneumonia. It had been thought that flu vaccine would prevent flu -- and pneumonia -- across all groups of seniors, but this benefit appears to be largely confined to younger, healthier seniors.
"In seniors, flu vaccine was not linked to a reduced risk of pneumonia," said lead researcher Michael L. Jackson, a postdoctoral fellow at the Group Health Center for Health Studies in Seattle.
This article references a newly released finding published in the Lancet…
The Lancet 2008; 372:398-405
Influenza vaccination and risk of community-acquired pneumonia in immunocompetent elderly people: a population-based, nested case-control study
Dr Michael L JacksonPhD
Pneumonia is a common complication of influenza infection in elderly individuals and could therefore potentially be prevented by influenza vaccination. In studies with data from administrative sources, vaccinated elderly people had a reduced risk of admission for pneumonia compared with unvaccinated seniors; however, these findings could have been biased by underlying differences in health between the groups. Furthermore, since most individuals with pneumonia are not treated in hospital, such studies should include both outpatient and inpatient events. We therefore assessed whether influenza vaccination is associated with a reduced risk of community-acquired pneumonia in immunocompetent elderly people after controlling for health status indicators.
1173 cases and 2346 controls were included in the study. After we adjusted for the presence and severity of comorbidities, as defined by chart review, influenza vaccination was not associated with a reduced risk of community-acquired pneumonia (odds ratio 0·92, 95% CI 0·77–1·10) during the influenza season.
The problem (as defined by me of course) with this finding and the resultant reportage is that in our "sound-bite" world the issue will not receive a critical and thorough airing.
My first (of several) problem with this paper is that there is no mention of the parties involved having been vaccinated against bacterial pneumonia. If the main aim of an influenza vaccine is to prevent pneumonia wouldn't getting a pneumonia vaccine be of benefit as well?
Secondly, it is known that although an influenza vaccine will not always prevent infection, it will attenuate severity of illness. This gets a bit "fuzzy" when we consider the differences between H1N1 and H3N2. The former produces a (generally) milder illness, the latter, more (generally) severe.
The Journal of Infectious Diseases 2005;192:249–257
© 2005 by the Infectious Diseases Society of America. All rights reserved.
Ville T. Peltola, et al.
Influenza A virus causes epidemics annually and pandemics several times a century. Two subtypes of influenza A virus, H3N2 and H1N1, are presently circulating in the human population. Epidemics caused by H3N2 are associated with higher mortality in human populations than are epidemics caused by H1N1 or influenza B virus.
The level of NA activity decreased in influenza viruses isolated from 1957 to 1968 and increased again in those isolated from 1968 to 1997. This trend in NA activity correlates with the observed historic mortality caused by H3N2 influenza viruses, which was highest in 1957, decreased during the next decade, but increased again during the 1990s (table 2). Low levels of NA activity in the influenza viruses circulating in 1968 is consistent with lower mortality from this pandemic, compared with that in the 1957 pandemic or during the epidemics caused by H3N2 influenza viruses during the 1990s. It has been suggested that conservation of the N2 NA in the influenza viruses circulating in 1968 resulted in relatively low mortality during this pandemic, but this does not explain why influenza viruses circulating later that had no antigenic shift in HA or NA caused higher mortality. The N2 NA in the influenza virus circulating in 1997 had the second highest level of NA activity, and this influenza virus caused the highest mortality during an epidemic since the 1957 pandemic.
The years encompassing the vaccine effectiveness analysis had a considerable amount of H3N2 circulating.
Another recent finding that sheds light on the effectiveness (or not) of vaccines:
The Journal of Immunology, 2006, 177: 7811-7819.
Copyright © 2006
Elizabeth P. Ryan, et al.
Vaccination to generate protective humoral immunity against infectious disease is becoming increasingly important due to emerging strains of virus, poorly immunogenic vaccines, and the threat of bioterrorism. […]The widespread use of nonsteroidal anti-inflammatory drugs and Cox-2-selective inhibitory drugs may therefore reduce vaccine efficacy, especially when vaccines are poorly immunogenic or the target population is poorly responsive to immunization.
The Journal of Infectious Diseases 2002;186:341–350
© 2002 by the Infectious Diseases Society of America. All rights reserved.
Jonathan A. McCullers and Jerold E. Rehg
A lethal synergism exists between influenza virus and pneumococcus, which likely accounts for excess mortality from secondary bacterial pneumonia during influenza epidemics. Characterization of a mouse model of synergy revealed that influenza infection preceding pneumococcal challenge primed for pneumonia and led to 100% mortality. This effect was specific for viral infection preceding bacterial infection, because reversal of the order of administration led to protection from influenza and improved survival. The hypothesis that influenza up-regulates the platelet-activating factor receptor (PAFr) and thereby potentiates pneumococcal adherence and invasion in the lung was examined in the model. […] The model of lethal synergism will be a useful tool for exploring this and other mechanisms underlying viral-bacterial interactions.
Attempting to pull it all together:
Elderly have a reduced antibody response to vaccinations.
Our circulating H3N2s have undergone a change for the worse when it comes to mortality.
Our influenza vaccine is given intramuscularly and the antibodies produced are the ones that have a lesser effectiveness at warding off illness [humoral vs. mucosal], and you must add to that the fact that the longer the time frame between inoculation and infection, the less effective these lesser effective antibodies become. The study offered no hints as to the lapse of time that may or may not have been at play.
The population analyzed tends to be on anti-inflammatory and/or COX-2 inhibitor medications, often at high levels.
Even a vaccine attenuated infection of H3N2 in a frail elderly person would seem to indicate a high level of risk of a secondary infection of pneumonia.
All-in-all, the issue is extremely complicated and our knowledge is evolving, as evidenced by the myriad refs I had to pull to make that point.
The effectiveness (or not) of a vaccine should not be reduced to statistical analysis of cases that were not even lab confirmed to be influenza.
Nor should effectiveness be written off when there are simple change-ups (no anti-inflammatory drugs for two weeks following immunization, intranasal vs. intramuscular inoculation) that might dramatically improve antibody response.
But none of that will even enter the picture as we all read the headlines Flu vaccine doesn't protect… and those that already don't believe in vaccine efficacy and overtly fear the miniscule risk(s) of receiving them will feel vindicated and supported in their (ill-informed) opinions and choice of abstention. And that "personal" choice places us all – and our children – at greater risk.