Wednesday, December 5, 2012

Mandatory Flu Shots for Healthcare Workers: Summary of the literature

Very few countries offer seasonal flu vaccines to their general (not high risk) populations, let alone mandate them for groups of healthy people.  With less institutional bias, the international literature usually fails to support mass flu vaccinations, for a variety of reasons.  Here are short excerpts from medical literature around the world of which I've previously made mention:

Hong Kong, China:  a meta-analysis found only 3 papers with placebo-controlled trials of flu vaccine in healthcare workers (HCWs):
There is a limited amount of evidence suggesting that receiving influenza vaccination reduces laboratory-confirmed influenza infections in HCWs.  No evidence can be found of influenza vaccinations significantly reducing the incidence of influenza, number of ILI [influenza-like illness] episodes, days with ILI symptoms, or amount of sick leave taken among vaccinated HCWs. There is insufficient data to assess the adverse effects after vaccination. 
Denmark:  Getting the 2009 swine flu vaccine was associated with a higher rate of developing swine flu disease in a young, high risk population.  Those who received the seasonal flu but not the swine flu vaccine in 2009 were twice as likely to get a case of swine flu compared to those receiving no vaccination, and 2.5 times as likely to be hospitalized for swine flu!

Canada:  six studies by Skowronski and others found approximately twice the risk of becoming sick from swine flu if you received a seasonal flu vaccination the previous year.

Both Portuguese and Dutch researchers found a poorer antibody response to flu vaccinations in subjects who received flu vaccinations in prior years.  The Dutch researchers also found that antibody levels lasted longer in those who did not get yearly flu shots.

There are studies of vaccine safety in healthcare workers.  In Australia, 1.3% of HCWs sought medical attention for an adverse event occurring soon after vaccination.  In Korea, 32% of military HCWs had some type of systemic adverse event post-vaccination.  In Japan, 23% reported a systemic adverse event within a week of vaccination, and 1.3% of HCWs reported a severe adverse event.  In Thailand, 24% of HCWs reported malaise and/or fatigue after a swine flu vaccination.

Is paralytic Guillain Barre syndrome (GBS) vaccine-related?  After the 1976 swine flu vaccine campaign, it was found that the vaccine increased GBS cases by a factor of 8.8 in the 6 weeks following vaccination.  In 2010 CDC suggested there were only 0.8 vaccine-attributable cases for every million swine flu vaccinations.  (This is estimated to be the approximate increase in GBS cases following flu vaccinations most years.)  

Interestingly, the Tennessee Department of Health did an exhaustive survey looking for GBS cases in the 2002-3 time period, and found that no single database was reliable:  
Although the use of large hospital discharge databases may be useful as an adjunct for identification of GBS cases as part of public health surveillance, they lack sufficient sensitivity or specificity to be relied upon exclusively. The poor specificity of the system is particularly problematic for public health surveillance... Additional methods of reliable and efficient ascertainment and verification of cases are crucial to ensure valid data... 
CDC used 3 databases for their analysis, but did not perform chart reviews to verify the validity of their data, as was done in Tennessee.  

A Harvard study that did do a chart review found an excess 5 GBS cases per million vaccinations following 2009-10 (unadjuvanted) swine flu vaccinations, but no significant increase following seasonal flu vaccinations that year.

A more recent CDC analysis of the same 2009-10 US data, using different methods, found 1.5 to 2.8 excess GBS cases per million vaccinations.

Following use of ASO3-adjuvanted swine flu vaccine in Canada, Quebec reported 2 excess GBS cases per million vaccinations.

University of Pennsylvania researchers found that flu vaccines from 1976, 1991-2 and 2004-5 induced antiganglioside (anti-GM1) antibodies in mice.  Anti-GM1 antibodies are associated with GBS.  Influenza itself (the disease) may also be associated with GBS.

What is the bottom line?

1.  Influenza is a common infectious disease that can range from severe or life-threatening to asymptomatic, whose mortality rate is uncertain

2.  Limited studies show that flu vaccinations may prevent some cases of flu, but not in the elderly or young children:  the groups at highest risk of severe outcomes.  In some circumstances vaccines may increase rates of flu.

3.  There is no body of literature showing that health care workers benefit personally or transmit less flu to patients as a result of vaccination, save patient lives or prevent patient hospitalizations.

4.  Flu vaccine frequently causes minor, annoying fatigue and malaise or "flu-like" symptoms.

5.  GBS and narcolepsy are rare but devastating illnesses that may be caused by flu vaccinations.

6.  Therefore, HCWs and all others should be allowed to decide for themselves whether to be vaccinated, especially since vaccines are given annually and their cumulative impact is unknown.

1 comment:

Anonymous said...

Thank you for your analysis of the literature on this subject.

As a healthcare worker who developed a serious adverse reaction (neuralgic amyotrophy) to the seasonal and H1N1 vaccines in December 2009 I have been dismayed by the widespread use of mandatory requirements for healthcare workers, without allowing them a personal exemption.

Even my employer, who was informed of my injury, still requires a physician's note to excuse me from having the vaccine. As I have learned, it's not likely that a physician could have predicted my adverse reaction nor could advise me currently if I would have another.

Thank you again for your thoughtful collection of this important set of studies.