Researchers are beginning to describe a phenomenon they are calling "long-Covid" – the persistence of symptoms long after a diagnosis of what was initially assumed to be just an acute illness.
Although we still lack large robust studies, long-Covid is now established as a real phenomenon and, for many, the burden of infection with Covid-19 does not end with discharge from hospital, with the disappearance of the virus, or with the fading of acute symptoms.
The available studies are largely individual or collated case-reports so, there is still no
accurate measure of just how common long-Covid is.
In June 2020, the Washington Post described multiple long-duration cases: individuals who had spent more than 60 days with serious symptoms. In July 2020, the Guardian reported on a study of 94 recovered patients at St Vincent's Hospital in Sydney, who agreed to undergo tests every three months to determine whether Covid-19 was associated with any lasting effects in the immune system, blood, lung, gut, and brain.
No data has yet been published but St Vincent's head of infectious diseases, Associate Prof Gail Matthews, reported one third of the study group are showing symptoms three to four months after being initially infected. Matthews also noted that, of the 10 per cent who were admitted to hospital, "around 80 per cent" still had some symptoms.
The UK Covid-19 Symptom Study, which uses an app to collect symptom information from nearly four million users, says collected data shows one in 10 people with Covid-19 are sick for three weeks or more.
Data on 640 individuals across Europe and US describe symptoms including fatigue, difficulty concentrating, insomnia, chills/sweats, loss of appetite, and headache, as well as fever, cough, and shortness of breath.
A more comprehensive study of the persistence of symptoms involved 143 patients in Italy who were assessed at an average of 60 days after symptom onset. Only 18 (12.6 per cent) were completely free of Covid-19 symptoms; 32 per cent had 1-2 symptoms and 55 per cent had three or more. The prolonged symptoms included fatigue, breathing difficulties, joint pain, and chest pain.
Larger, formal studies are now underway, including the UK-based "Post-Hospitalisation Covid-19 Study" of 10,000 Covid-19 patients who, after discharge from hospital, are being followed for 12 months. The aim is to establish a clearer picture of the prevalence and persistence of long-term outcomes and to develop appropriate treatment protocols.
The Reggio Emilia (Italy) Covid-19 working group assembled and reported on a cohort of 2653 patients who were initially diagnosed between February 27 and April 2, 2020. This research group is now re-contacting survivors to participate in a follow-up study. The data is not published in the scientific literature yet but, again, the researchers have established there are a variety of persistent symptoms: pain, tingling, depression, fatigue, short-term memory loss, hair loss, and the need for hours of extra sleep.
"Almost half the patients" say they are not cured.
Indeed, from observations made so far in multiple places, the symptoms of long-Covid cover a wide range from the non-specific to some particular and rare manifestations. They include pain, fever, "brain fog" (loss of the ability of concentrate), shortness of breath, heart arrhythmias, and hypertension.
It is also clear from studies directly focused on severe organ damage, particularly of the brain and heart, that Sars-CoV-2 infection causes a wide spectrum of abnormalities – and these may help us understand the wider persistence of milder but still debilitating symptoms.
In addition, there is data on the persistence of the virus itself. A study in the Netherlands of 129 patients detected infectious virus shedding in 23 (17.8 per cent) and the median duration of shedding of eight days after onset of symptoms. While the probability of detecting infectious virus dropped below 5 per cent by 15 days, in one patient, infectious virus was detected up to 20 days after onset of symptoms.
In addition to the about one in 100 infected people who die within a month of being infected with Covid-19, a wide spectrum of multi-organ symptoms persist long after the virus has been cleared.
Although we currently know very little about the prevalence, severity, or duration of long-Covid, it may be with us for decades.
• John D. Potter is a professor with the Centre for Public Health Research at Massey University in Wellington.
Those interested in an expanded version of this essay with references to the evidence (mostly in the scientific literature) please go to: https://blogs.otago.ac.nz/pubhealthexpert/2020/09/24/the-long-term-health-burden-of-covid-19-further-justification-for-nzs-elimination-strategy/