Seven of the 22,000 medical workers vaccinated against H1N1 swine flu have developed side effects, the Health, Labor and Welfare Ministry said.

The finding, released Oct. 23, was revealed to ensure the new vaccine was working on doctors and nurses at 67 designated hospitals run by the National Hospital Organization.

Four of the seven developed serious side effects, including vomiting and diminished consciousness, but all are recovering, the ministry said. The other three complained of minor symptoms, such as developing hives.

Meanwhile, other hospitals reported that 25 patients were exhibiting adverse effects from the new vaccine, including two serious cases.

The ministry said half of the 32 people who developed symptoms were found to have food and drug allergies or allergic asthma.