New Study: Women Are Twice More Prone to ‘Severe’ Reaction to Flu Jab

A medical worker receives a dose of the COVID-19 vaccine at Tokyo Medical Center. Reuters
A medical worker receives a dose of the COVID-19 vaccine at Tokyo Medical Center. Reuters
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New Study: Women Are Twice More Prone to ‘Severe’ Reaction to Flu Jab

A medical worker receives a dose of the COVID-19 vaccine at Tokyo Medical Center. Reuters
A medical worker receives a dose of the COVID-19 vaccine at Tokyo Medical Center. Reuters

Women are twice as likely to suffer a “severe” reaction to the flu jab as men, a new study has revealed.

Analysis of 34,000 adults who received the flu vaccination between 2010 and 2018 found that 3 percent of women had a severe reaction, compared to just 1.5 percent of men, according to The Telegraph.

Researchers from the University of Montreal, Canada, classified severe reactions as symptoms such as high fevers over 39 degrees, or significant swelling, pain or rashes known as erythema, that led to people being unable to carry out daily tasks.

The study, published in the Journal of Epidemiology and Community Health, found that women were also around a third more likely to suffer from other, less serious side effects than men.

It said that 38.6 percent of the 20,295 women analyzed had suffered side effects like headaches, vomiting, fevers and muscle aches after their vaccination, known as “systemic reactions”, compared with just 28.6 percent of the 13,860 men (around 29 percent fewer on the whole).

Rarely serious

The study said for every 1,000 people getting the flu vaccine, 74 more women would have these side effects than men.

Researchers also found that women were 31 percent more likely to get pain, swelling or an infection around the injection site. It said this happened to 44.6 percent of women and 33.9 percent of men.

Dr. Marilou Kiely, author of the report, said while “most reactions are mild, self-limited and rarely serious”, a bad reaction could “be a barrier” to having another vaccination.

“Transparent communication regarding the increased risk for females would potentially help sustain long-term trust in health authorities and vaccines,” she said.

Dr. Conall Watson, a consultant epidemiologist at the UK Health Security Agency (UKHSA), said that “serious side effects are rare following a flu jab”.

Hospitalization and death

“Flu can cause very serious illness, hospitalization and death. Some people are more susceptible to the effects of flu - flu can trigger heart attacks, or lead to pneumonia, and can make existing medical conditions worse,” he said.

The NHS stresses that “severe allergic reactions” like anaphylaxis are very rare at around one in one million and that some of the reactions categorized as severe in this study, such as erythema, usually resolve on their own, even if they are uncomfortable.



Blood Tests Allow 30-year Estimates of Women's Cardio Risks, New Study Says

A woman jogs in a park in Saint-Sebastien-sur-Loire near Nantes, France January 19, 2024. REUTERS/Stephane Mahe/File Photo Purchase Licensing Rights
A woman jogs in a park in Saint-Sebastien-sur-Loire near Nantes, France January 19, 2024. REUTERS/Stephane Mahe/File Photo Purchase Licensing Rights
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Blood Tests Allow 30-year Estimates of Women's Cardio Risks, New Study Says

A woman jogs in a park in Saint-Sebastien-sur-Loire near Nantes, France January 19, 2024. REUTERS/Stephane Mahe/File Photo Purchase Licensing Rights
A woman jogs in a park in Saint-Sebastien-sur-Loire near Nantes, France January 19, 2024. REUTERS/Stephane Mahe/File Photo Purchase Licensing Rights

Women’s heart disease risks and their need to start taking preventive medications should be evaluated when they are in their 30s rather than well after menopause as is now the practice, said researchers who published a study on Saturday.

Presenting the findings at the European Society of Cardiology annual meeting in London, they said the study showed for the first time that simple blood tests make it possible to estimate a woman’s risk of cardiovascular disease over the next three decades.

"This is good for patients first and foremost, but it is also important information for (manufacturers of) cholesterol lowering drugs, anti-inflammatory drugs, and lipoprotein(a)lowering drugs - the implications for therapy are broad," said study leader Dr. Paul Ridker of Brigham and Women’s Hospital in Boston, Reuters reported.

Current guidelines “suggest to physicians that women should generally not be considered for preventive therapies until their 60s and 70s. These new data... clearly demonstrate that our guidelines need to change,” Ridker said. “We must move beyond discussions of 5 or 10 year risk."

The 27,939 participants in the long-term Women’s Health Initiative study had blood tests between 1992 and 1995 for low density lipoprotein cholesterol (LDL-C or “bad cholesterol”), which are already a part of routine care.

They also had tests for high-sensitivity C-reactive protein (hsCRP) - a marker of blood vessel inflammation - and lipoprotein(a), a genetically determined type of fat.

Compared to risks in women with the lowest levels of each marker, risks for major cardiovascular events like heart attacks or strokes over the next 30 years were 36% higher in women with the highest levels of LDL-C, 70% higher in women with the highest levels of hsCRP, and 33% higher in those with the highest levels of lipoprotein(a).

Women in whom all three markers were in the highest range were 2.6 times more likely to have a major cardiovascular event and 3.7 times more likely to have a stroke over the next three decades, according to a report of the study in The New England Journal of Medicine published to coincide with the presentation at the meeting.

“The three biomarkers are fully independent of each other and tell us about different biologic issues each individual woman faces,” Ridker said.

“The therapies we might use in response to an elevation in each biomarker are markedly different, and physicians can now specifically target the individual person’s biologic problem.”

While drugs that lower LDL-C and hsCRP are widely available - including statins and certain pills for high blood pressure and heart failure - drugs that reduce lipoprotein(a) levels are still in development by companies, including Novartis , Amgen , Eli Lilly and London-based Silence Therapeutics.

In some cases, lifestyle changes such as exercising and quitting smoking can be helpful.

Most of the women in the study were white Americans, but the findings would likely “have even greater impact among Black and Hispanic women for whom there is even a higher prevalence of undetected and untreated inflammation,” Ridker said.

“This is a global problem,” he added. “We need universal screening for hsCRP ... and for lipoprotein(a), just as we already have universal screening for cholesterol.”