Post-menopausal women may be more likely to get severely ill with coronavirus, according to research.
Researchers from King's College London say their findings suggest high levels of oestrogen protect against Covid-19.
They analysed data from almost 600,000 women in the UK who use the COVID Symptom Study app.
People who have the app report how they feel every day, including if they develop symptoms of the coronavirus or get a test result.
Results showed post-menopausal women were 22 per cent more likely to report symptoms of Covid-19 than women who still had periods.
They were also more likely to be hospitalised and need respiratory support — an indication of severe Covid-19.
The findings suggest HRT — drugs which contain artificial oestrogen to help relieve symptoms of the menopause, such as hot flushes — may boost the immune system.
Data showed HRT appeared to lessen the severity of Covid-19 in post-menopausal women because they were less likely to need hospital care.
Younger women on the combined contraceptive pill, which contains oestrogen, also had lower rates of Covid-19 symptoms than women who did not.
Post-menopausal women may be at a higher risk of getting coronavirus, according to a recent study (stock)
Oestrogen is a sex hormone that's responsible for the development and regulation of the female reproductive system.
Levels of oestrogen plummet in post-menopausal women and can influence how the body functions — including the immune system.
The researchers, led by Dr Ricardo Costeira, suggested oestrogen could protect against Covid-19.
This could explain why the disease and MERS — another related type of coronavirus — pose more of a threat to men more than women.
The experts wrote: 'It has been well-illustrated that females generally mount greater inflammatory, antiviral, and humoral immune responses than males.'
They added that this contributes to better clearance of viruses, including SARS-CoV-2 — which causes Covid-19.
The study looked at 44,000 post-menopausal women who stopped having periods within the last five years. They were 53.8 years old, on average.
Menopause is defined as the changes a woman goes through as she stops getting her periods and is no longer able to get pregnant naturally. Around 60 per cent experience symptoms resulting in behavioral changes and one in four will suffer severely.
Common symptoms include hot flushes, night sweats, vaginal dryness leading to discomfort during sex, disrupted sleep, decreased sex drive, problems with memory and concentration and mood swings.
Menopause happens when your ovaries stop producing as much of the hormone oestrogen and no longer release an egg each month.
In the UK, the average age for a woman to reach the menopause is 51, according to the NHS.
The average age for a woman to reach menopause – when regular periods stop – is 51.
The data of the first group was compared against 108,000 pre-menopausal women who still regularly menstruated.
Results showed that post-menopausal women were 22 per cent more likely to report Covid-19 symptoms.
They reported typical tell-tale signs of a persistent cough and loss of taste and/or smell (anosmia).
But they reported a fever, hoarse voice, loss of appetite and muscle pains at far higher levels.
Often in studies that rely on self-reporting Covid-19 symptoms say the higher the number of symptoms, the more severe the disease.
This study measured severe Covid-19 based on if the patients were hospitalised or needed respiratory support.
Post menopausal women were four per cent more likely to be hospitalised and 60 per cent more likely to need respiratory support than those still menstruating.
But the experts admitted it was not a significant difference. The findings were not published in a medical journal.
Academics did not look at whether certain groups of women were likely to catch the virus in the first place.
Older people are more vulnerable to the coronavirus because their immune systems are weaker and they cannot clear the virus as quickly.
But the researchers adjusted the results for age, as well as body mass index (BMI) and smoking which are both suspected as risk factors for Covid-19.
The link was still apparent after accounting for these