Though the concept isn't new, concurrent COVID-19 and flu infections have been dubbed "flurona" as more cases have been publicly reported, according to The Washington Post.
Six things to know:
1. "Flurona" recently became a popular internet search term after Israel's Beilinson Hospital reported two pregnant women testing positive for both COVID-19 and flu. They were treated to reduce their fevers, placed in isolation and eventually left with healthy babies, Arnon Vizhnitser, the hospital's director of gynecology, told the Post.
2. Flu and COVID-19 co-infections aren't new. A study from China in January 2020 found zero cases of coinfection among 99 COVID-19 patients, but a follow-up a month later at a COVID-19 hospital found about 1 in 8 patients had both illnesses at the same time, according to The Atlantic. Co-infection cases were reported in the U.S. nearly two years ago.
3. Both respiratory infections can prompt similar symptoms, such as fever, coughing, fatigue, runny nose, body aches, sore throat and diarrhea. Both can be fatal.
4. Experts say COVID-19 and flu vaccines are the best way to prevent severe infections. "If you are vaccinated, the disease is very mild," Dr. Vizhnitser said of both COVID-19 and the flu. "Women who were not vaccinated [against the coronavirus] were very sick."
5. While many countries track COVID-19 and flu cases, there's little data on co-infections. Edsel Salvana, MD, a member of a technical advisory group to the Philippines health department, said such co-infections aren't unusual and that the Philippines' first COVID-19 death was an early pandemic patient who had COVID-19 and influenza B, along with streptococcus pneumonia, according to ABS-CBN News. However, other experts disagree on the prevalence of co-infections. David Edwards, PhD, aerosol scientist and bioengineering professor at Cambridge, Mass.-based Harvard University, told Bloomberg, "The probability of both of those things happening at the same time is sort of like the probability of getting robbed by two people on the same day. It happens, but it's not like people should think, 'Oh, there's gonna be this flurona that's going to overtake omicron.' That's not going to happen."
6. Despite the term's rising popularity, not everyone is a fan. "Stop this 'flurona' BS. Co-infections of circulating respiratory viruses happen all the time," Angela Rasmussen, PhD, virologist, tweeted Jan. 5. In a follow-up tweet, she added, "They can, obviously, cause co-infections (infect the same host at the same time). This has unpredictable results in terms of pathology but it doesn't necessarily make you twice as sick."