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‘Reassuring’ figures on breakthrough infections


Jolyon Attwooll


11/10/2021 4:35:02 PM

Deaths from ‘breakthrough’ infections are most likely to happen among the elderly but vaccination hugely diminishes risk, recent studies suggest.

Older man in ICU.
The risk of breakthrough infections that develop into severe COVID appears to be highest among older age groups.

One of the largest analyses on ‘breakthrough’ infections was published last month by the Office of National Statistics (ONS) in the UK, which categorised the age and vaccination status of those who died from COVID-19 in England between 2 January and 2 July this year.
 
There were 256 deaths from breakthrough infections among the 51,281 who died with COVID-19 in the country. That figure that does not include fully vaccinated people who were infected with the virus before they received their final dose. 
 
The risk was greatest among older age groups with the median age of those who died from breakthrough infections standing at 84.
 
For Dr Khayyam Altaf, Chair of RACGP Specific Interests Aged Care, the low number of breakthrough deaths in the ONS report is positive news.
 
‘Overall, I find it very reassuring,’ Dr Altaf told newsGP. ‘What it shows is that the vaccine is very effective. And we already know that it’s not guaranteed.’
 
Of the breakthrough deaths, the ONS reports there were more among males (61.1%), and that 13.1% of those who died were likely to be immunocompromised.

Dr Altaf also says elderly people are more likely to have received their vaccines earlier and would represent a higher percentage of the vaccinated population in the study.
 
It is a point made by the ONS researchers, who advise caution in drawing definite conclusions. They write that the numbers are likely to reflect the characteristics of those who are fully vaccinated, as well as the risks of breakthrough deaths.
 
Another caveat is the period of the analysis, as it meant none of the people who had breakthrough infections were likely to have been vaccinated more than six months ago and as a result, immunity would not have waned significantly.
 
Other studies overseas have presented a similar picture, although more recent analyses confirm breakthrough infections increase alongside the proportion of vaccinated people.
 
A report published by Centers for Disease Control and Prevention (CDC) also suggests the risk of breakthrough infections is greatest in those over the age of 65. However, the risk remains far greater for unvaccinated people – its most recent data records 0.5 weekly deaths recorded per 100,000 fully vaccinated people for those older than 65, compared to 4.3 among the unvaccinated of the same age.
 
On a more local level, the number of deaths caused by breakthrough infections so far in the state of Massachusetts – roughly the same size as Victoria in Australia – have been recorded as 254 in total, with a median age of 82. Of those, 71% reportedly had other underlying health conditions.
 
In Singapore, where the vaccination rollout is further advanced and restrictions have somewhat eased, the latest Ministry of Health report records that 29.8% of deaths in the most recent 28 days were fully vaccinated. That compares to 83% of its population having had a full course of vaccines.
 
Dr Altaf says the figures in the ONS study are likely to reflect the greater chance of chronic health problems in older age-groups.
 
‘We have to remember that elderly individuals will have more co-morbidities,’ he said.
 
‘Some may have COVID, and they might die of something completely different, they might die of cancer or a heart attack.
 
‘But if they've been diagnosed with COVID in the 28 days before their death, then that will come up in those statistics. There’s a lot of variables that are at play.’
 
Evidence of the trajectory of breakthrough cases in Australia is also now emerging, particularly for NSW, where there is more detail on those who have had the disease.
 
In the most recent COVID-19 weekly epidemiological surveillance report issued by NSW Health, which covers until 25 September, the number of new local cases that are fully vaccinated is reported as 8.4% of the total.
 
That report cites 32 deaths among fully vaccinated people (10.7% of the total) since this year’s outbreak began. Of those, two people were in their 50s, 10 were in their 70s, 10 in their 80s and 10 aged more than 90.
 
Dr Altaf believes future phases of the vaccination rollout will help increase protection.
 
‘The other important thing will be the booster jabs,’ he said. ‘Once we’ve caught up there with the initial jabs, and start rolling out the booster jabs, those figures will look even better.’
 
The Australian Technical Advisory Group on Immunisation (ATAGI) is due to confirm details of a  booster program and its timing by the end of this month.
 
Last week, the group recommended a third dose for immunosuppressed individuals – a process it says is part of the primary vaccination process.
 
For any future booster program, those aged over 70 are likely to be first in line due to their greater vulnerability to COVID-19 infection, as well as the likelihood of having received their vaccine doses earlier on in the rollout.
 
Dr Altaf advises a cautious approach as states begin to open up.
 
‘It would be lovely to see a bit of normality by Christmas, particularly for elderly individuals,’ he said.
‘I think we still need to keep those precautions up. The one thing [family members] can do is get vaccinated to reduce the chance of death and protect loved ones.’
 
For him, however, the ONS study is a source of optimism.
 
‘From the point of view of Australia, we’re looking good as long as we can reach those vaccination targets,’ he said.
 
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