Concern is generating among scientists the appearance of a type of influenza with a strange and disconcerting mutation. There are at least two human cases recorded with these new strains called “double mutants” H1N1 influenza.
The two cases were detected in American patients, reported the Centers for Disease Control and Prevention of that country (CDC, its acronym in English).
According to the organization, These genetic changes could reduce the effectiveness of Tamiflu, until now the main antiviral on the market against influenza.
This week, the magazine Emerging Infectious Diseases, edited by the CDC, published a study of the new H1N1 flu viruses with these two worrying mutations, which scientists call I223V and S247N, that describe changes in key proteins on the surface of the virus.
The report coincides with one published in March by Hong Kong scientists, who were the first to discover these two mutations. Through laboratory experiments, published in March, they found that The two mutations appeared to increase H1N1 resistance to oseltamivir treatment, commonly sold under the brand name Tamiflu by the pharmaceutical company Roche.
It is not clear to what extent mutations could reduce the drug’s effectiveness in the real world. Laboratory tests found that the mutated viruses were up to 16 times less sensitive to the antiviral, a smaller drop than in some worrying previous mutations.
Despite this, The CDC does not believe there is still a need for alarm. “These mutated viruses retained sensitivity to other influenza drugs, including a newer one, baloxavir marboxil. “There are no immediate implications for changing clinical care decisions,” a CDC spokesperson told CBS News, adding that vaccination still offers protection against mutated viruses.
In spite of the “rapid spread of dual mutants to countries on different continents”, the CDC report found that mutations appear to remain rare for now.
According to CBS News, since the mutations first appeared in a case sampled in the Canadian province of British Columbia in May 2023, A total of 101 sequences have been submitted to the GISAID global virus database from Africa, Asia, Europe, North America and Oceania. These represent less than 1% of the flu virus sequences during that time.
“However, it is possible that these data do not necessarily represent the true proportion of what was in circulation due to differences in surveillance and sequencing strategies in each country”said the authors of the report.
The two American cases were detected by laboratories at the Connecticut Department of Health and the University of Michigan last fall and winter.
“It is unknown how widely these mutated viruses will circulate in the coming season. “It is important to continue to monitor the spread of these viruses and the evolution of these viruses,” the CDC spokesperson said.
Oseltamivir is the treatment most prescribed for influenza, according to the CDC. A study published last year found that the drug made up 99.8% of flu antivirals prescribed to children.
According to the portal of the American Association of Retired People (AARP, its acronym in English, it is an American organization that serves the interests of older people) Tamiflu decreases flu symptoms in about a day. “If I woke up with aches, cough and fever, I would take Tamiflu as long as I could get it within the first 24 hours,” explained Mark Ebell, a family physician in the Department of Epidemiology and Biostatistics at the U of Georgia, who has studied the effectiveness of the drug.
“I will feel better a day or a day and a half before, and that is worth it to me. But I would not take it if more than 24 hours had passed since the symptoms appeared.”
Tamiflu works preventing infected cells from bursting and thus releasing the flu virus that can infect nearby cells. This process must be stopped early – most guidelines say this within 48 hours of the onset of symptoms – to make a difference.
According to AARP, a CDC study of pregnant women who had the 2009 flu pandemic, indicated that those who received antiviral treatment more than four days after falling ill were six times more likely to end up in intensive care than those who took the medication within the first two days.
CDC urges doctors to administer influenza antivirals as soon as possible to all hospitalized flu patients or who are at risk of serious illness. Doctors have also turned to oseltamivir to treat humans infected by the ongoing H5N1 bird flu outbreak on dairy farms this year.
