Vials of H1N1 vaccine by manufacturer CSL are displayed near its production line in Melbourne on September 24, 2009 as a program to develop a swine flu vaccine in Australia has produced a vaccine which its maker says will have a 95 per cent success rate in adults. The first five million doses of swine flu vaccine will be available to Australians next week and 21 million doses of the vaccine provided by January next year, but children under 10 will have to wait until at least October. Trials are underway to ensure the vaccine is safe in children.  AFP PHOTO/William WEST (Photo by William WEST / AFP) (Photo by WILLIAM WEST/AFP via Getty Images)
CNN  — 

The US Centers for Disease Control and Prevention says it will test a sample from a 42-year-old woman who is believed to have died of a swine flu infection in Brazil in May.

When it receives the sample, the agency says, it plans to look for possible mutations that may have made the virus more contagious or more dangerous.

According to the CDC, testing by a Brazilian health agency showed that the virus is genetically linked to previously detected swine flu infections in people in Brazil from 2020 to 2022.

“CDC’s top priority is to confirm that the patient was infected with an influenza A(H1N1)v virus,” CDC spokesperson Kathleen Conley told CNN in a statement. “If virus isolation is successful, additional virologic characterization may be performed.”

The World Health Organization reports that the woman who died this year had two close contacts who worked at a swine farm near her home, but neither of the contacts tested positive for the virus.

“Based on the information currently available, WHO considers this a sporadic case, and there is no evidence of person-to-person transmission of this event. The likelihood of community-level spread among humans and/or international disease spread through humans is low,” WHO said in a news release Friday.

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In 2009, an H1N1 swine flu pandemic killed an estimated 151,700 to 575,400 people globally. In the aftermath, authorities and scientists stepped up surveillance of pig populations for viruses with “pandemic potential.”

Swine flu usually happens in people who come in contact with infected pigs. Symptoms are similar to that of regular human influenza and can include fever, lethargy, lack of appetite, coughing, runny nose, sore throat, nausea, vomiting and diarrhea.