Is oestrogen helping protecting women against Coronavirus?
There’s a lot of talk in the media about women being better protected against the coronavirus than men.
Depending on which country you look at the death rate among men is two to three times higher and the big question is why? The reasons put forward include genes, oestrogen and lifestyle.
So, what do we know about these so far?
Let’s take Oestrogen first. We know oestrogen plays a protective role in many aspects of women’s health. It is part of the reason women have a lower rate of heart disease and recent research is showing it may also have a role in reducing the risk of dementia and also type 2 diabetes. It also plays a vital role in protecting bone health and reducing osteoporosis (brittle bones.)
Declining oestrogen levels are also associated with the familiar symptoms of menopause including night sweats, mood swings, depression and anxiety as well as vaginal atrophy and stress incontinence (to name a few).
But when it comes infectious diseases what is the link? There appears to be a few ways it could impact.
During previous flu outbreaks (Influenza A) and also SARS and MERS outbreaks researchers noticed a similar pattern with women doing better than men – so they set out to find out why.
They designed a number of studies and according to UK gynaecologist and menopause expert, Vikram Talaulikar, some showed oestrogen may be a factor.
“In these studies, oestrogen reduced flu virus replication in nasal cells from women but not men,” he says.
How? The mechanism appears to be related to oestrogen receptors on our cell or what’s known as oestrogen receptor signalling.
Cells have protein receptors that act like locks and keys to allow or stop molecules binding with them. This in turn affects how the cell functions, including their ability to reproduce. In this case, a particular form of oestrogen appears to have stopped the virus from replicating by interfering with how it uses the cell’s machinery to attach itself, grow and multiply.
“Sex differences in susceptibility to the SARS virus in mice parallel those observed in patients and also identify oestrogen receptor signalling as critical for protection in females,” Mr Talaulikar says.
“It is possible -but not proven- that premenopausal women on certain kinds of birth control pills or post-menopausal women on hormone replacement therapy (HRT) may be better protected during seasonal influenza epidemics,” he adds, but with an important caveat – many of these these are animal studies.
Professor Stanley Perlman, a microbiologist and immunologist from Iowa University in the USA was involved with one such study on mice found females fared better with SARS until their oestrogen levels were depleted by either removing their ovaries or suppression.
He says it shows oestrogen plays a role, but as he told the New York Times, humans are not mice: “It’s an exaggerated model of what happens in humans. The differences between men and women are subtle — in mice, it’s not so subtle.”
Mr Talaulikar adds: “It is possible that oestrogen helps the body’s immune system in fighting viral infections like COVID-19. But before we reach a firm conclusion on this, there is plenty more well-designed research needed.”
Apart from oestrogen receptor signalling, simply being born a woman could be an advantage.
We all have genes on our chromosomes that play a part in our immune response. These are located on the X chromosome. Woman have two X chromosomes but men have an X and a Y.
This could mean that women can mount a more efficient immune response, producing more of the cells that are needed to fight the virus more quickly.
And that brings us to a third hypothesis – oestrogen may play a role in regulating the inflammatory response.
Some studies have shown that one form of oestrogen (E2) in particular could be relevant here. Once again it looked at the Influenza A virus (AIV) and found that mice treated with E2 had a better immune response than those treated with a placebo. They had a higher survival rate and they produced more neutrophils that enhanced the ability of the immune system cells to do their job and clear the virus.
Another form of oestrogen – E3 – may play a role in ensuring the immune system doesn’t overreact according to another study– and this is important too. If the immune system goes into overdrive it can cause what’s known as a cytokine storm.
Cytokines are proteins released by many cells in the body, including those in the immune system. They help coordinate the body’s response against infection and trigger inflammation. But if it goes to far it causes a hyper-inflammatory response, or too much inflammation and this can cause serious problems and even death.
The study showed that E3 was protective and helped reduce inflammatory response without impacting on the ability of the immune system to combat the flu virus.
There are other reasons that may explain why women aren’t as badly affected by Covid19, Mr Talaulikar reminds us.
“Lifestyle differences between men and women, and finally the protective effects of oestrogen on cardiovascular health of women,” are factors too, he says.
In general women don’t smoke or drink as much as men and their burden of diseases such as heart disease, diabetes or chronic lung conditions is lower – and all of these have been significant factors in the higher death rate among men during Covid19.
So, is it all because of oestrogen? At the moment researchers are saying it’s too soon to say exactly what role it plays. While much of the data we’re relying from is coming from the 45,000 confirmed cases in China, and that sounds like a big sample pot – it’s not big enough and it’s too early to say.
You can book with Vikram Talaulikar by clicking here.