Association Between Adverse Events of Special Interest and Pandemic (H1N1) 2009 Monovalent Vaccine Without Adjuvant, by Age Group and Risk Interval, November 1, 2009–February 28, 2010.

<p>Abbreviation: CNS, central nervous system; IRR, incidence rate ratio; CI, confidence interval.</p>a<p>Risk (exposed) periods were days after each pandemic (H1N1) 2009 monovalent vaccination. Control (unexposed) periods were postvaccination time period outside the exposed periods.