Well spotted Margo, thanks. I also found the note interesting.
"Such an observation may seem counterintuitive, but it is possible that influenza vaccines alter our immune systems non-specifically to increase susceptibility to other infections; this has been observed with DTP and other vaccines. (Benn et al, Trends in Immunology, May 2013) There are other immune mechanisms that might also explain the observation."
Expression of a certain amount of 'surprise' is seemingly in order. It is more than 'possible', it has indeed been observed many times; why would it then be counterintuitive?
Skowronski: Association between the 2008-09 seasonal influenza vaccine and pandemic H1N1 illness during Spring-Summer 2009: four observational studies from Canada. https://www.ncbi.nlm.nih.gov/pubmed/20386731
Due to these outcomes Skowronski later carried out an animal study in which the vaccinated animals also showed clinical H1N1 effects. https://www.ncbi.nlm.nih.gov/pubmed/24475142
The adjuvanted H1N1 vaccine caused anaphylaxis in some people, admittedly a small number, but here, 20 times the normal reported rate for non-adjuvanted vaccines). These immune system effects need to be borne in mind as it's possible they should be game-changers. Increased risk of anaphylaxis following administration of 2009 AS03-adjuvanted monovalent pandemic A/H1N1 (H1N1pdm09) vaccine, https://www.ncbi.nlm.nih.gov/pubmed/24144473