August 21, 2019

Patricia K. Doyle-Baker1, Andrew Stewart2

1 Human Performance Lab, Faculty of Kinesiology, University of Calgary, Calgary AB T2N 4N1
2Department of Community Health Services, Cumming School of Medicine, University of Calgary, Calgary AB T2N 4N1 

A growing body of literature suggests that not only do overweight and obese individuals experience a greater proportion of negative outcomes as a result of influenza exposure but also vaccination response differs across age groups and sex. For example, during the 1918 flu pandemic males aged 20–40 years had higher influenza death rates than females (Gagon et al., 2013). More recently, the amount of physical activity has been found to be associated with upper respiratory tract infections (Neiman, 1994) and antibody production to the influenza vaccine (Kohut et al., 2002). Our study aimed to investigate the potential role of specific lifestyle factors (body composition and physical activity) on the effectiveness of influenza immunization in young men.

Individuals infected with a virus (antigen) or immunized, develop detectable antibodies within a short time period. This is referred to as seroconversion because the antibodies outnumber the antigens. To prevent infection or achieve seroprotection the antibody level must increase above the 50% clinical protection threshold (Coudeville et al., 2010). However, antibody number varies by influenza subtype and individual age when immunized. In this study, the trivalent seasonal influenza vaccine contained three circulating subtypes: A/Texas, A/California, and B/Massachusetts. As such, our main outcomes included whether participants achieved seroconversion and seroprotection with respect to the specific influenza subtypes.

Our prospective design used a rolling recruitment with a duration of 3 months, which began at the start of the autumn flu vaccination period. Out of 131 Albertan males (age 18-35 years) that responded to the online survey, 125 met the inclusion criteria and 76 attended the baseline session, which included a fasting blood draw, percent body fat (%BFat) measurement (dual X-ray absorptiometry) and completion of a physical activity questionnaire. Forty-five (median age 23 years, %BFat range: 9-32) returned for a post vaccination blood draw 4 weeks after receiving the flu vaccine.

The seroconversion rate ranged between 57 and 72% and the greatest seroprotection occurred for the A/California and B/Massachusetts strains. No significant differences were found when comparing seroconversion rates for the three strains while accounting for %BFat. The seroconversion rate, however was influenced by the influenza sub type and level of physical activity. Significant differences were found for the A/Texas strain (p<0.01) such that males with a high physical activity score were determined non-seroconverters and those with a low physical activity score exhibited seroconversion.

In summary, those males with the highest physical activity score had a lower immune response to the influenza vaccination for the A/Texas subtype. Previous research has suggested that moderate levels of physical activity have a more positive vaccine response when compared to higher levels which result in a negative effect (Cooper et al., 2007). Our sample however, represented a subset of the North American population with lower adiposity (%BFat mean: 17) when compared to a similar age range (20-39 years) who typically have higher adiposity (%BFat mean: 26) (Li et al., 2009). This was all somewhat unexpected; however, we must be cautious given the lower than anticipated return rate, the lack of previous influenza vaccination in our sample, and the exploratory nature of the study.

Key Findings:

  • From a public health perspective, it is important to recognize that not everyone who is vaccinated achieves the same influenza vaccine response.
  • The inclusion of lifestyle factors (e.g., physical activity volume) in future research may help identify why some young men do not derive universal protection from the influenza vaccine.

Original Article:

Stewart A, Vanderkooi O, Reimer R, Doyle-Baker PK. (2018, Aug.). Immune Response in Highly Active Young Men to the 2014/15 Seasonal Influenza Vaccine. Appl. Physiol. Nutr. Metab. 43(8):769-774. doi: 10.1139/apnm-2017-0683. Epub 2018 Feb 26.

This article is a summary of an article published in Applied Physiology, Nutrition and Metabolism. If you intend to cite any information in this article, please consult the original article and cite that source. This summary was written for the Canadian Society for Exercise Physiology and it has been reviewed by the CSEP Knowledge Translation Committee.