London - Receiving hormone replacement therapy within six months of a recorded diagnosis of Covid-19 was associated with a reduction in mortality from the infectious disease among women, finds a study indicating the role of oestrogen in fighting the deadly virus.
While men and women are equally susceptible to the Sars-CoV-2 virus, men tend to have more severe infections and have higher rates of hospitalisation and mortality.
A recent review of sex differences in Covid-19, using data from 38 countries, found mortality in men was 1.7 times higher than in women. Younger women or those with higher oestrogen levels are less likely to experience Covid-19 complications.
Earlier studies have also shown that women have faster and greater immune responses to viral infections.
Researchers have observed similar data in previous pandemics, including the Sars-CoV (Severe Acute Respiratory Syndrome Coronavirus) and MERS-CoV (Middle East Respiratory Syndrome Coronavirus) outbreaks.
Although the reason for these sex differences is uncertain. Limited recent observational data suggest that oestrogen may reduce the severity of Covid-19 disease.
The new study, led by researchers at the University of Southampton in the UK, showed that hormone replacement therapy (HRT) was associated with a 22 per cent reduction in all-cause mortality in Covid-19.
HRT is a medication to replace the oestrogen that the human body stops making during menopause.
The finding suggests that oestrogen may well contribute to a protective effect against Covid severity. This may explain why fewer women compared to men have been hospitalised, admitted to intensive care, or died due to Covid-19 during the pandemic.
"This study supports the theory that oestrogen may offer some protection against severe Covid-19," said Christopher Wilcox from the varsity.
The study, published by Oxford University Press in the journal Family Practice, investigated the association between hormone replacement therapy or combined oral contraception use and the likelihood of death in women with Covid-19.
Researchers investigated combined oral contraception, which contains oestrogen because some recent observational data suggests that women taking oral contraceptives have a lower risk of acquiring Covid-19.
They identified a group of 1,863,478 women over 18 in England. There were 5,451 Covid-19 cases within the cohort.
Wilcox noted that the study provides "reassurance to patients and clinicians that there is no indication to stop hormone replacement therapy because of the pandemic".
This comes even as Britain is experiencing an acute shortage of HRT, which is used by about one million women in the UK, owing to an increase in demand.