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• With the focus on Covid-19, it is easy to forget that the ‘regular’ seasonal flu can also be dangerous
• The flu can also lead to complications like pneumonia and worsen certain chronic health conditions, including heart disease
• To help prevent the flu, experts say that getting the flu shot is more important than ever 

Amid the Covid-19 pandemic, a new US study serves as a reminder of how severe the seasonal flu can be.

Researchers found that among 90 000 Americans hospitalised with the flu, 12% had a serious heart complication, including heart attack and sudden heart failure. Many ended up in the intensive care unit, and 7% died in the hospital.

The study shows that Covid-19 isn’t alone among viruses that can up the odds for heart events.

The findings also underscore the importance of getting the flu shot – especially this year, experts said.

Flu shot always recommended

“The flu is not ‘just a cold’,” said Dr Kathryn Edwards, a professor at Vanderbilt University School of Medicine in Nashville. “People often don’t appreciate how serious it can be.”

A yearly flu shot is always recommended, she said, especially for people older than 65 and those with certain chronic conditions such as heart disease, diabetes and asthma. They are at heightened risk of flu complications.

This season, flu vaccination is particularly important because of the pandemic, Edwards said. That’s in part to avoid having hospitals overrun by both flu and Covid patients.

Edwards, who was not involved in the study, is also a spokesperson for the Infectious Diseases Society of America.

While the flu usually causes temporary miseries like fever, cough and a sore throat, it can also lead to complications such as pneumonia and other secondary infections. The infection can also worsen certain chronic health conditions, including heart disease.

Body-wide inflammation

But that is not necessarily common knowledge, said Dr Shikha Garg, the senior researcher on the new study.

“I don’t know that these cardiac complications are on people’s radar,” said Garg, of the US Centers for Disease Control and Prevention. “This study shows just how common they are.”

For the study, Garg’s team looked at 90 000 flu hospitalisations in 17 US states between 2010 and 2018. Just under 12% of those patients suffered a heart complication.

Not surprisingly, people with existing heart conditions were at greater risk: 21% of those patients had a cardiac complication – as did 19% of patients with kidney disease and 15% of those with diabetes.

Edwards said the flu may directly trigger heart complications, by spurring body-wide inflammation. If, for example, a person has artery-clogging “plaques”, that inflammation could rupture the plaque and lead to a heart attack.

Of study patients with heart complications, almost one-third landed in the ICU, and 7% died.

No guarantee against the flu

Despite the severity of the flu, Americans frequently skip the annual vaccine. During the 2018–2019 season, the CDC says, between 34% and 56% of adults got the flu shot, with variations by state.

“Everyone age six months and older should be vaccinated,” Edwards said.

The shot is no guarantee against the flu, she added, but it is typically about 50% effective. And even if it does not prevent the infection entirely, Edwards said, it may reduce the severity of the illness.

“We don’t know for sure what’s going to happen in the fall,” Garg said. But since both the new coronavirus and the flu are likely to be in circulation, she added, Americans should be prepared.

Flu vaccine safe

“Now more than ever,” Garg said, people should get the flu shot.

It is possible, Edwards noted, that the efforts in place to battle Covid – from physical distancing to hand-washing to mask-wearing – will take some of the bite out of flu season. But those things do not take the place of vaccination, she said.

Garg agreed. “The flu vaccine is safe, and it’s our most important tool for prevention.”

The findings were published in the Annals of Internal Medicine.

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• A study found that heart failure patients who had received flu and pneumonia vaccines had a lower risk of in-hospital death 
• It is a known fact that respiratory infections make heart failure worse 
• Despite that, very few heart failure patients receive these immunisations

Flu and pneumonia vaccines lead to fewer hospital deaths among heart failure patients, a new study finds.

“Our study provides further impetus for annual immunisations in patients with heart failure. Despite advice to do so, uptake remains low,” said study author Dr Karthik Gonuguntla, of the University of Connecticut.

In heart failure, your heart can’t pump blood as well as it should. This leads to fluid buildup in the lungs that causes shortness of breath, coughing and reduced quality of life.

Lower in-hospital death rate

Respiratory infections like pneumonia and the flu make heart failure worse, so annual vaccinations are recommended for patients. However, few studies have compared outcomes among heart failure patients who have and haven’t received these vaccinations.

In this study, the researchers looked at nearly three million heart failure patients, average age 70, in the United States who were hospitalised between 2010 and 2014. Only 1.4% of the patients had received the flu vaccine and just 1.4% had received the pneumonia vaccine.

Rates of in-hospital death were much lower among patients who received the flu and pneumonia vaccines (just over 1% for each) than among those who didn’t receive either vaccine (almost 4%), the researchers found.

The study findings were released on Friday and scheduled for presentation at the European Society of Cardiology virtual annual meeting.

Pandemic changed perceptions

“Pneumonia and flu vaccines are vital to preventing these respiratory infections and protecting patients with heart failure. Although many people have rejected common and safe vaccines before Covid-19, I am optimistic that the pandemic has changed perceptions about the role of immunisations in safeguarding our health,” Gonuguntla said in a society news release.

Serious reactions to flu and pneumonia vaccinations are rare, occur within a few hours and can be treated, he said.

Studies presented at meetings should be considered preliminary until peer-reviewed for publication in a medical journal.

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