Before revision:  The findings are robust for the second digit tests, for a sub-sample of countries with regional data, and during the previous swine flu (H1N1) 2009-2010 pandemic  .
After revision:  The findings are robust for the second digit tests, for a sub-sample of countries with regional data, and during the previous swine flu (H1N1) 2009-2010 pandemic . The paper further highlights the importance of independent surveillance data verification projects .