Sunday, May 23, 2010

H1N1 vaccine can cause false positive HIV test

May 21, 2010 •

Vacina contra H1N1 pode gerar falso positivo em teste de HIV

The Department of sexually transmitted diseases, AIDS and Viral Hepatitis of the Ministry of Health released a technical note on the possibility of false-positive results in enzyme immunoassays for HIV among people who received the vaccine against swine influenza virus. 

As the department was due to accelerated industrial production of vaccine against the H1N1 virus, there is currently no available data on all the side effects, but it was observed that people who took the vaccine to be tested for HIV-1 showed false positive, ie, the results indicated that the AIDS virus is present when, in fact, is not. 

According to the Ministry of Health, this is because, in taking the vaccine, the body begins to produce antibodies Immunoglobulin M (IgM), the body's first defense against infection. In this process, the presence of antibodies directed to other infectious agents that may be similar to HIV, produce false positive results in examinations. 

Under the guidance of the Department of STDs, if tested positive, it is recommended to perform a verification result. The second examination should not be reactive in case of cross-reactivity with antibodies produced in response to the vaccine against swine influenza virus. Still, the negative result in these tests does not rule out HIV infection, since the patient may be in the state of seroconversion, or other disease that interferes with the results. 

The Ministry of Health recommended that the professionals responsible for diagnosing HIV-1 should inform patients who received the swine flu vaccine on the possibility of false positive results in tests. If necessary, patients should also call for the creation of a new collection after 30 days, until the diagnosis is definitive. more...