The COVID-19 pandemic has hit men and women differently. While men are more vulnerable to severe acute COVID-19 infection, women are more prone to develop long COVID.
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On the other hand, pregnancy might increase the chances of hospital admission, making COVID-19 vaccines strongly recommended for expectant mothers.
Here, Cosmos looks at the latest evidence on how COVID-19 is affecting women.
Women are less vulnerable to COVID-19 yet more prone to long COVID than men
Since the beginning of the pandemic, it has been clear that men are worse off than women when catching COVID-19. Regardless of age and other underlying health conditions, men are more likely to experience severe disease and have worse outcomes, such as the need for intensive care and death.
In a large study conducted in New York City, published in June in Nature, researchers examined the medical data of over 6,000 patients aged 18 or over who were hospitalised with COVID-19 in the city in 2020.
They found that although men were less likely than women to have certain comorbidities, such as obesity and hypertension, they nevertheless had an increased likelihood of mortality and need for intensive care.
Why men are more vulnerable to COVID-19 than women is still unclear, says Professor Alex Polyakov, an obstetrician and senior lecturer at the University of Melbourne. “But we do know that women and men have different immune systems that function differently,” he says.
The different immune responses men and women have to infections can also explain why women might be more prone to develop chronic symptoms after acute infection.
Women tend to have more overactive immune systems than men, which might help them short-term cope with injuries and infections but puts them at an increased risk of developing chronic COVID-19 symptoms.
“We know this because most autoimmune diseases, such as rheumatoid arthritis and many others, are more common in women,” says Polyakov.
Early reports of long COVID at a Paris hospital between May and July 2020 suggested that women afflicted by persisting COVID-19 symptoms after acute infection outnumbered men by four to one. Another study that aimed at quantifying long COVID in the US and the UK found that young to middle-aged women were disproportionately affected.
COVID-19 outcome during pregnancy
COVID-19 has been associated with increased risks of preeclampsia, preterm birth and other adverse pregnancy outcomes.
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Polyakov says pregnant women might be twice as likely to end up in ICU than those who are not pregnant, and they are also more likely to die from the infection. “This makes physiological sense because pregnant women already rely on reserves, in terms of breathing and in terms of oxygen,” he says.
Pregnancy itself places a lot of stress on the body, which leaves the pregnant person more vulnerable to illness. That is why vaccination against the flu is recommended during pregnancy in Australia. In pregnancy, Polyakov says, the reserve the body would normally employ to fight infections and diseases are deployed to sustain the foetus.
In addition, he explains that pregnancy is an immunocompromised state. “The woman’s body tolerates a foreign body, the foetus, and therefore the immune system is downregulated,” he says.
While the risk of severe COVID-19 infection is present throughout pregnancy, it is towards the end of the second trimester and throughout the third trimester that pregnant people tend to experience the worst symptoms.
Towards the end of pregnancy, lung volume is reduced and lung capacity restricted by the growing baby. Breathing can become more difficult. “COVID affects the lungs, and in pregnancy you’re relying on your reserves. If an infection depletes those reserves in the lungs, you’re more likely to end up on a ventilator because you can’t breathe on your own,” Polyakov says.
COVID vaccines in pregnancy and breastfeeding
Because of the risks COVID-19 poses during pregnancy, the Pfizer COVID vaccine is recommended at any stage of pregnancy in Australia.
“On the balance of risk, there is no doubt that [COVID] vaccination is indicated in any stage of pregnancy,” says Polyakov. He says pregnant people who receive mRNA COVID vaccine before or during pregnancy are less likely to contract the COVID-19 infection and experience severe symptoms and adverse pregnancy outcomes.
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That is not unexpected or necessarily a bad outcome, says Polyakov. “There are thousands, if not millions of different antibodies that cross the placenta and are secreted in breast milk, and there has never been a study that demonstrates those antibodies are detrimental to the foetus,” he says. “There is no one reason to think that COVID antibodies are in any way special and will cause problems.”
There are vaccines – for instance for rubella (German measles) and chickenpox – that should never be administered during a pregnancy, but are strongly recommended for people planning to get pregnant
Polyakov says women receive many vaccines throughout their life and produce a multitude of antibodies. The only effect that has on the unborn is protecting them in the first few months of life. That is why the whooping cough vaccine is recommended during pregnancy and why breastfeeding is highly beneficial for newborns.
Following the same logic, anti-COVID-19 antibodies passed on to the unborn might offer some level of protection from COVID-19 to the baby.