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Health workers administer Covid-19 tests outside a building placed under lockdown in Hong Kong. Photo: Bloomberg

ExplainerHow dangerous is ‘flurona’ – a Covid-19 and flu double whammy – as Omicron spreads?

  • The winter flu season and more contagious variants of Covid-19 make more co-infections just a matter of time, experts say
  • Vaccines can protect against both the seasonal flu and Sars-CoV-2 viruses, the WHO points out
Israel recently reported its first case of a simultaneous Covid-19 and seasonal influenza infection, refreshing fears of a more such co-infections.

While the case – involving an unvaccinated pregnant woman – has received global attention, this is not the first time that such a co-infection, dubbed “flurona”, has occurred.

Given the busy winter flu season and the continued spread of Covid-19, including highly transmissible variants like Omicron, experts say more cases are a matter of time.

So how common is flurona and should we be concerned? Here is what we know so far.

What is ‘flurona’ and is it new?

Flurona has recently gained popularity as a moniker for a simultaneous infection by the flu and Covid-19 viruses. It is not a new variant of Sars-CoV-2, the virus that causes Covid-19.

It is possible to be infected with the flu, other respiratory illnesses, and Covid-19 at the same time, according to the US Centres for Disease Control and Prevention.

“It’s not that you get one and [these] are mutually exclusive and [you’re] not getting the other,” World Health Organization incident manager Abdi Mahamud said.


No reason for existing vaccines to fail against Omicron, says WHO

No reason for existing vaccines to fail against Omicron, says WHO

Researchers around the world have considered the possibility of catching Covid-19 at the same time as other respiratory diseases since the pandemic began, and their findings have been well documented.

Researchers with Tongji Hospital in the Chinese city of Wuhan found co-infection with Sars-CoV-2 and influenza virus was highly prevalent in the early stages of the outbreak there. According to their June 2020 paper in the Journal of Medical Viruses, nearly half of the 307 Covid-19 patients studied were also infected with the influenza A virus, while 7.5 per cent had influenza B.

Two months before, University of Stanford researchers in northern California had found one instance of Sars-CoV-2 and influenza co-infection.

And in May that year, the Hospital Clinic of Barcelona reported four cases of Sars-CoV-2 and influenza co-infection – in an 81-year-old woman and three men aged 53, 78, and 56.

Scientists find pandemic-flu collision doubles Covid-19 transmission

In Iran, researchers from the Alborz University of Medical Sciences found 79 such co-infections reported from December 2019 to September 2020.

Six co-infections were also detected by researchers with the Feevale University in Brazil, out of more than 400 specimens collected between March and December 2020.

How is flurona transmitted?

According to the WHO, the flu and Covid-19 viruses spread between people in similar ways: through droplets and aerosol when an infected person breathes, speaks, coughs or sneezes.

People may also become infected if they touch their eyes, nose or mouth after touching surfaces or objects contaminated by the virus.

What are the symptoms?

Both diseases cause similar symptoms, such as fever, cough, fatigue, sore throat, and muscle and body pain.

But Covid-19 can also cause loss of smell or taste, and more serious symptoms such as shortness of breath. It can also trigger more severe illness in some people, take longer to show symptoms, and cause patients to be contagious for longer, according to the US CDC.

Is flurona a cause for concern?

Some experts say there is reason for worry, as both diseases can cause severe illness and death, although others have observed that simultaneous infections are still quite rare.

Authorities in Israel are looking into whether co-infection has the potential to cause more serious illness, although the pregnant woman who was the first recorded case in the country only had mild symptoms and was discharged in generally good health, according to the Beilinson Hospital in Petah Tikva.

University of Hong Kong virologist Jin Dong-Yan, however, said co-infections were not a big threat since they were relatively rare.

“Seasonal flu is not seen in many places where people still practise social distancing. It was gone from Australia, New Zealand or Hong Kong in 2020 and 2021,” Jin noted.

But with some countries relaxing public health control measures, the flu has made a comeback and prompted worries that it will cause a “twindemic”, a severe flu season during the Covid-19 pandemic.

The US CDC saw hospitalisation due to flu-like illness more than double last year. Even in China, where strict public health measures are still in place, the flu positivity rate is also rising, and is higher than the previous season in hospitals being monitored.


Unvaccinated in the Philippines ordered to stay home under measures to fight Covid-19 case surge

Unvaccinated in the Philippines ordered to stay home under measures to fight Covid-19 case surge

“Flu season has started in a lot of countries and we have seen a drop in flu vaccination. We can see the [disease] trend is going up,” WHO’s Mahamud told a virtual press briefing from Geneva on January 4.

“That’s our biggest worry, if you remember when we talked about the twindemic. All the measures to push down Covid have pushed out the flu. Now we are relaxed. Most people are not vaccinated and the flu will come back strongly.”

In many countries, last year’s flu season was the least severe one in a long time due to public health interventions for Covid-19, which worked for flu as well and were still in place.

China scientists link Covid-19 measures to fall in other infections

A respiratory diseases doctor in Beijing, who declined to be named as he was not authorised to speak to the media, said he believed such risk of co-infection would be low in China where Covid-19 was less prevalent.

“We will be more likely to get flu and other respiratory diseases on the job, and people should be vaccinated or take other precautionary measures for protection from such diseases as well,” he said.

How can I protect myself against flurona?

Protective measures for both flu and Covid-19 are similar: obeying social distancing rules, wearing a mask, observing hand hygiene and getting vaccinated.

Flu vaccines have been around for decades and are updated annually. Existing Covid-19 vaccines are still providing protection against severe illness, hospitalisation and death, even with the spread of highly mutated variants such as Omicron, according to WHO.

“Our message strongly is, yes, it’s possible [to have co-infection] and we may see it because we let down measures that are protective,” Mahamud said in reiterating the need for vaccination. “We have effective flu vaccines and effective Covid vaccines that can protect you from both viruses.”