The Central Epidemic Command Center (CECC) has recently received feedbacks from some people who have developed influenza-like symptoms such as fever after receiving the pandemic influenza A (H1N1) vaccine and thought they have become infected with pandemic influenza A (H1N1) because of the vaccination after they have been tested positive for influenza virus by the rapid diagnostic test.CECC would like to clarify that both the domestically produced vaccine and the foreign vaccine contain inactivated influenza virus.In other words, the vaccine contains only part of the virus that is strong enough to induce immunity in the recipient but will not result in influenza infection.People who are tested positive for influenza virus by the rapid diagnostic test are most likely infected prior to vaccination.The time from the person is infected until he/she develops symptoms (incubation period) is usually a few days.Therefore, they did not develop symptoms at the time of vaccination even if they were already infected with influenza.On the other hand, some people who have been vaccinated might have become infected with influenza virus before they develop immunity.Hence, getting the pandemic influenza A (H1N1) vaccine does not cause pandemic influenza A (H1N1) infection.

Further, CECC pointed out that it takes about two to three weeks after vaccination to develop sufficient immunity in the recipient. As a result, people who have received the vaccine should still take measures against influenza, including washing hands frequently, wearing a mask when sick, and resting at home when sick, in order to ensure their own health and the health of others.