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Does vaccination reduce long COVID risk?
Research suggests illness severity and vaccination status influence the chance of patients seeking medical care in the six months post-infection.
Unvaccinated people are more likely to have increased medical presentations during the six months post-COVID infection.
More evidence has emerged suggesting people who are unvaccinated are at higher risk of ongoing COVID-19 symptoms 28 or more days after infection.
The finding is based on a US cohort study of 1832 adults, published in JAMA Network, which examined factors associated with persistent post-COVID-19 symptoms, and how the associated medical presentations for these symptoms change over time.
The researchers discovered that while COVID-19 is associated with increased medical presentations in the six months post-infection, being vaccinated against the disease may lower the risk of long-term symptoms.
Dr Ken McCroary is a member of the RACGP Expert Committee – Quality Care, as well as the lead GP on the college’s south-west Sydney long COVID working group.
He told newsGP the study’s findings come as little surprise and add to the ‘no-brainer’ argument that vaccines are the safest way of preventing significant disease, hospitalisation and long-term sequelae.
‘Without the vaccine we’d all be in strife,’ he said.
‘There’s no question that now, whether you get access to [antiviral] medications or not, if you’re not vaccinated, your outcomes are always going to be statistically worse.’
But despite evidence showing the vaccines’ effectiveness against a number of different outcomes, Dr McCroary believes the messages still needs reinforcing, particularly in the lead up to winter with more booster shots and influenza vaccination drives likely.
‘The winter peaks will be one of the next challenges,’ he said. ‘Trying to vaccinate the cohort again, prior to the influenza outbreaks which will no doubt be with the next COVID outbreak.
‘It’s going to be another massive undertaking, on top of all the other things that general practices are trying to deal with at the moment.’
Participants in the study comprised 1118 males and 714 females aged 18–44 years of age with no marked comorbidities, of whom 77% were unvaccinated at the time of SARS-CoV-2 infection.
Higher rates of more severe symptoms were noted among the unvaccinated, while rates of symptoms lasting 28 or more days post-COVID onset were ‘significantly’ greater among this cohort.
Similarly high rates of long-term symptoms were also noted among those who reported having ‘moderate’ or ‘severe acute’ symptoms.
Supporting previous research, the US study found that participants who were vaccinated prior to COVID-19 onset were ‘significantly less likely’ to report 28 or more days of illness. However, among unvaccinated participants, post-infection vaccination was also associated with a 41% lower risk of reporting symptoms at six months.
A total of 728 participants (39.7%) had symptoms that lasted 28 days or more, with half reporting symptoms that lasted 90 or more days. The most common symptoms that rated ‘moderate’ or ‘severe’ one month after symptom onset were:
- fatigue (6.5%)
- exercise intolerance (5.9%)
- difficulty breathing (4.7%)
- loss of sense of smell and/or taste (5.3%)
- cough (3.8%).
In a six-month post-infection survey, 9.8% of these participants reported ongoing COVID-19 symptoms.
Meanwhile, every participant – regardless of vaccination status or disease severity – was more likely to seek medical care for lung issues, diabetes, neurological issues, and mental health-related illness for at least six months post-infection, compared with their use of healthcare services pre-COVID.
‘We also noted a high frequency of medical encounters for other organ system diagnoses up to several months after symptom onset,’ the authors wrote.
‘Taken together, this represents a substantive burden of medical care utilisation after COVID-19, even after adjusting for healthcare use prior to COVID-19 infection.’
The findings match with Dr McCroary’s experience and he believes GPs will expect to continue to see more presentations with COVID now a constant presence in the community.
‘During our [COVID] waves we see a lot more deterioration in comorbidities with people’s diabetes control, chronic obstructive pulmonary disease control, all deteriorating during their infection – and over the pandemic anyway,’ he said.
‘We’ve all seen increased symptoms and increased long symptoms, particularly in those who are unvaccinated and have higher pre-existing comorbidities, and we’re seeing it replicated everywhere.
‘So it’s definitely something we are seeing now and we’re expecting to see for the future.’
But Dr McCroary said ‘the challenging part’ can lie in keeping track of the numbers of people developing long-term symptoms.
‘That can be anywhere between 10–85%, depending on where you are, how you got the infection, whether you’re vaccinated, whether you’re in ICU,’ he said.
‘And we’re still seeing COVID infections and deaths all the time, we’re seeing the long-term complications all the time and it’s only becoming greater in terms of the numbers.
‘It just reflects again, the increasing burden placed upon the profession at times when the profession is being challenged with viability because of chronic underfunding.’
The US study authors’ conclusion echoes the ‘major burden’ that post-COVID symptoms place on healthcare systems, with their research offering further evidence that ‘post-infection vaccination may mitigate’ these impacts and better inform vaccination policies.
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