Examining factors that worsen coronavirus severity

Evelyn Lewin

12/03/2020 3:33:45 PM

Certain factors influence the case fatality rate for patients infected with COVID-19, with experts advising such patients to take extra precautions.

Man having blood pressure checked.
Experts believe patients with factors known to worsen the severity of coronavirus infection should receive closer monitoring.

Older age, hypertension, cardiovascular disease, chronic respiratory disease, diabetes, cancer.
These are all factors that may worsen the severity of infection for patients with COVID-19 (coronavirus).
That is what Dr Katherine Gibney, epidemiologist at the Peter Doherty Institute for Infection and Immunity and Austin Health Infectious Diseases Physician, told newsGP.
‘Obviously, the most data has come out of China but there’s also emerging data from other countries,’ Dr Gibney said.
From that data, the highest risk factor for worsening the severity of the infection is older age.
‘The case fatality gets up to about 15% for people who are 80 and older, which is very high,’ Dr Gibney said.
However, severity of the infection ‘really picks up’ after age 60.
‘It’s not zero under 60, so it’s not like all younger people can feel completely at ease, but it definitely picks up with increasing age,’ she said.
Dr Gibney is keen to note those numbers have not been adjusted for comorbidities.
‘So there’s probably a lot of overlap between that and the comorbidities that are associated with increased risk,’ she said.
According to a new study published in The New England Journal of Medicine on 28 February, the only age group spared by severe infection appears to be children aged under 14.
Of the underlying factors associated with worsening coronavirus symptoms, Dr Gibney said cardiovascular disease is the most significant.
While the exact impact of coronavirus on the cardiovascular system remains unclear, the American College of Cardiology outlined some of the cardiovascular conditions associated with the virus.
‘[T]here have been reports of acute cardiac injury, arrhythmias, hypotension, tachycardia, and a high proportion of concomitant cardiovascular disease in infected individuals, particularly those who require more intensive care,’ they state.
According to travel medicine website Coronavirus Travax, the case fatality rate for patients who had no comorbid conditions is currently listed as 0.9%.
Meanwhile, the coronavirus case fatality rate for patients with other factors is currently:

  • 10.5% for people with cardiovascular disease
  • 7.3% for people with diabetes
  • 6.3% for people with chronic respiratory disease
  • 6% for people with hypertension
  • 5.6% for people with cancer
But there may be more factors that worsen the severity of coronavirus infection, according to Monique Chilver, infectious diseases researcher at the Discipline of General Practice at the University of Adelaide.
‘There’s another one that’s a big one that hasn’t been reported as widely, and that’s smoking,’ she told newsGP, highlighting the fact people who smoke are not getting enough oxygen in their lungs.
‘So the body tries to compensate by making more epithelial lung cells.
‘Because there are more cells there, there are more cells for the virus to attack, so smoking is often associated with worse symptoms.
‘It’s a huge risk factor.’
factors-worsen-coronavirus-article.jpgDr Katherine Gibney (left) and Monique Chilver.

Dr Gibney said there is no clear-cut answer when it comes to the pathophysiology of why the other conditions may worsen the severity of coronavirus infection.
‘I don’t think we fully know,’ she said.
‘We know that the SARS-CoV-2 virus that causes COVID-19 binds to ACE-2 receptors to enter cells, but quite how that relates to the increased risk among older people and those with comorbidities is unclear.
‘I think we’re still trying to work that out.’
Dr Diana Rojas Alvarez is an infectious diseases epidemiologist at James Cook University. She told newsGP it is ‘still unknown’ why these factors make the disease more severe.
‘It is a new virus and nobody is doing the basic research to establish the “why” yet,’ she said.
‘However, these same factors increase the risk of severity of other infectious diseases like flu, pneumonia, urinary tract infections and others.’
Dr Rojas Alvarez adds that, in public health and clinical practice, it is not necessary to understand why a certain condition may lead to worsening symptoms of infection in order ‘to take action and implement recommendations if it is going to save lives’.
‘We can do research after the crisis … to understand the “why”,’ she said.
Instead of focusing on why these factors worsen the severity of the disease, Ms Chilver said it is important to use this information to protect vulnerable populations.
‘We really need to be looking at ways of minimising the spread to ageing people, especially those in residential aged care facilities, being exposed,’ she said.
It is also imperative to test people who fall into current testing criteria who have factors that put them at greater risk of more severe disease.
‘Currently there aren’t any treatments for COVID-19 available,’ Ms Chilver said.
‘Hopefully, by the time we see sustained transmission in Australia, there will be a treatment available and we will be able to treat anybody in a high-risk group who returns a positive test.’
Until then, patients with comorbidities that may worsen infection severity, or those who smoke or are of increasing age, should also be aware that they are at ‘higher risk’.
Dr Gibney agrees.
She said GPs should advise patients with identified risk factors  to partake in extra precautionary measures.
‘It’s about giving advice to patients – particularly those who are vulnerable to more severe disease – about social distancing and making sure that they try and minimise their risk of getting COVID-19,’ she said.
That includes thinking twice about modes of transport, such as not taking crowded public transport, along with not attending mass gatherings with more than 1000 people in attendance.
‘And I know that’s easier said than done,’ Dr Gibney said. ‘But for those people you might want to be a little bit more cautious in terms of avoiding very crowded places.’
Dr Gibney also recommends advising such patients to ensure they get more of their prescriptions filled, so they can avoid spending time in pharmacies, ‘where unwell people might congregate’.
Such patients should also receive closer monitoring.
‘For example, daily phone calls to check on them so they can be advised to present to hospital if they need to,’ Dr Gibney said.
Lastly, patients with these comorbidities should also be ‘really clear’ about family or friends not visiting if they are unwell.
The RACGP has more information on coronavirus available on its website.
Log in below to join the conversation.

cardiovascular disease coronavirus COVID-19 diabetes hypertension respiratory disease smoking

newsGP weekly poll What areas of healthcare were you hoping would get more funding in this year's Federal Budget?

newsGP weekly poll What areas of healthcare were you hoping would get more funding in this year's Federal Budget?



Login to comment

Dr Ian Mark Light   19/03/2020 7:40:44 AM

When the respiratory tract infections hit in winter in the colder states we will be very challanged and need very high level planning - maybe 1 in 5 clinics will concentrate on the URTI's and LRTI's certainly with new patients and home visits with the full PPE will have to increase as well as Tent Clinics in outside areas .
Climate change with warmer weather to June gives us time though the long range weather predictions have not been released.