Several Swiss cantons have a lack of swine flu vaccine at present because demand is exceeding supply.
This is particularly the case for canton Basel City, according to its health director, Carlo Conti.
Conti told the Basler Zeitung newspaper that the government had calculated distribution of the vaccine according to population figures produced by the Federal Statistics Office.
But this, he said, did not take into account factors that were specific to some cantons.
For example, in Basel City, many doctors had patients - children, women and workers - who lived in other cantons.
However, he said the problem would be resolved in the next few days when more vaccine stocks would be delivered.
While there has been criticism that the vaccination against the A (H1N1) flu is in a state of "chaos", Conti refuses to use the word. But he said improvements could be made in logistics and distribution.
He also recalled that there were distribution difficulties in other countries.
swissinfo.ch and agencies