Sunday, September 06, 2015

Study Suggests Low Dose Aspirin Doesn’t Reduce Flu Vaccine Immune Response



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Although it doesn’t answer all of the questions, we’ve a new study that suggests that using low-dose aspirin doesn’t significantly reduce the immune response from flu vaccines in elderly persons, a concern which we’ve looked at several times over the years.


About six years ago, in A Few Inflammatory Remarks, we saw several studies that suggested that taking antipyretic medications – like acetaminophen, Aspirin, or other NSAIDs – could reduce the effectiveness of some vaccinations or blunt the level of acquired immunity from actual infection.


A study by researchers at the University of Rochester, appearing in the journal  Cell Immunology (see Ibuprofen and other widely used non-steroidal anti-inflammatory drugs inhibit antibody production in human cells) warned:


The implications of this research are that the use of widely available NSAIDs after infection or vaccination may lower host defense. This may be especially true for the elderly who respond poorly to vaccines and heavily use NSAIDs.

A study appearing in the Lancet found a similar dampening effect on vaccine response in children given acetaminophen to control post-injection fever.  They advised:


Although febrile reactions significantly decreased, prophylactic administration of antipyretic drugs at the time of vaccination should not be routinely recommended since antibody responses to several vaccine antigens were reduced.


A couple of months later, in Anti-Inflammatory Meds And Vaccines, we saw animal studies  from the University of Missouri that specifically called out low-dose aspirin as potentially attenuating the effects of flu vaccination.  From their press release.


Aspirin, Tylenol May Decrease Effectiveness of Vaccines

Wednesday, December 02, 2009 :: Staff infoZine

Mizzou scientists discover aspirin and Tylenol block enzymes that could inhibit vaccines

Columbia, MO - infoZine - With flu season in full swing and the threat of H1N1 looming, demand for vaccines is at an all-time high. Although those vaccines are expected to be effective, University of Missouri researchers have found further evidence that some over-the-counter drugs, such as aspirin and Tylenol, that inhibit certain enzymes could impact the effectiveness of vaccines.

If you’re taking aspirin regularly, which many people do for cardiovascular treatment, or acetaminophen (Tylenol) for pain and fever and get a flu shot, there is a good chance that you won’t have a good antibody response,” said Charles Brown, associate professor of veterinary pathobiology.

(Continue . . . )


The operative word in the above title being `May’, as what works in animals, or in vitro experiments, doesn’t always pan out in the human population. 

Today we’ve the results of a study that looked at the immune response to a single, specific flu vaccine (2009 monovalent H1N1)  in older adults who were taking low-dose aspirin, and compared that to elderly adults not taking LD aspirin, and came away with encouraging news.   


Low-dose aspirin use does not diminish the immune response to monovalent H1N1 influenza vaccine in older adults

M. L. JACKSONa1 c1, A. BELLAMYa2, M. WOLFFa2, H. HILLa2 and L. A. JACKSONa1

a1 Group Health Research Institute, Seattle, WA, USA

a2 The EMMES Corporation, Rockville MD, USA


Non-steroidal anti-inflammatory drugs (NSAIDs) may inhibit antibody production by peripheral blood mononuclear cells; one consequence of this could be decreased effectiveness of vaccines in NSAID users. Because many older adults use low-dose aspirin for primary or secondary prevention of coronary events, any inhibitory effect of aspirin on vaccine immune response could reduce the benefits of vaccination programmes in older adults.

We tested whether immune response to vaccination differed between users vs. non-users of low-dose aspirin, using data from four randomized trials of monovalent 2009 pandemic influenza A(H1N1) vaccine. Geometric mean haemagglutination inhibition antibody titres were not significantly lower in low-dose aspirin users compared to non-users. Our results provide reassurance that influenza vaccination effectiveness is probably not reduced in older adults taking chronic low-dose aspirin.

(Accepted August 19 2015)


While encouraging, a few caveats apply here.

This was a limited study, that only looked at the immune response to one specific flu shot, in an elderly cohort that normally sees a reduced immune response to flu vaccines.  How LD aspirin use might affect the immune response in younger individuals wasn’t determined.


This study only looked at low-dose aspirin use, and therefore cannot be automatically assumed to apply to other NSAIDs or antipyretics, or larger doses of aspirin.


Still, for those who take a daily LD aspirin, this should provide some peace of mind that they probably aren’t sabotaging their yearly flu shot.

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