Delta more dangerous than Alpha, study suggests

6 minute read

Communicable Disease COVID-19 Live blog

By

Bianca Nogrady

And door-to-door covid testing can significantly increase testing rates among at-risk communities, study finds.

Welcome to The Medical Republic’s COVID Catch-Up.

It’s the day’s covid-19 news in one convenient post. Email bianca@biancanogrady.com with any tips, comments or feedback.

30 August

The Delta variant is associated with at least a two-fold greater risk of hospitalisation than the Alpha variant, a study has found.
A paper published in Lancet Infectious Disease presented an analysis of data from more than 43,000 covid-positive individuals – nearly 8700 of whom were infected with the Delta variant and more than 34,000 with the Alpha variant.
Researchers found that people infected with the Delta variant were 2.3-times more likely to be hospitalised within 14 days of testing positive than those infected with the Alpha variant, after adjusting for factors such as age, ethnicity, and socioeconomic factors.
Three-quarters of all those admitted to hospital with either Alpha or Delta infections were unvaccinated. However the increased risk of hospitalisation with Delta was evident even among vaccinated individuals, even though their overall risk of hospitalisation was substantially lower than in unvaccinated individuals.
Commenting on their findings, the authors wrote that “outbreaks of the delta variant in unvaccinated populations might lead to a higher health-care burden, particularly compared with the previous prevalent SARS-CoV-2 strains.”

Door-to-door covid testing can be a more effective way of reaching certain populations and communities than static local testing facilities, researchers say.
A study, published in JAMA Health Forum, compared testing rates overall and in different demographic groups resulting from three different approaches of door-to-door community-based covid testing in an area of San Jose with a large Latinx population.
The testing was done by local community health workers, who were assigned either to areas with high numbers of confirmed cases, areas with the highest potential positivity rate – decided using machine learning – or based on health workers’ local knowledge of areas where testing was needed.
Overall, 756 tests were conducted, and the proportion of Latinx individuals who were tested was 80%-184% higher than testing conducted at a local church or fairground testing site. The door-to-door testing approach also tested a higher proportion of women and individuals aged over 65 years.
The overall test positivity rate in the door-to-door testing was lower than that seen at local testing sites, which the authors suggested may relate to a higher proportion of symptomatic individuals getting tested at local fixed testing sites.
However selection of locations by machine learning did have a higher positivity rate than seen at the church or fairground, or in either of the other door-to-door testing approaches. “In this community-based intervention with community health workers, we found that allocating COVID-19 tests using machine learning can increase testing capacity, reduce demographic disparities in testing, and detect clusters of infected individuals,” the authors wrote.

The Pfizer vaccine is now approved for use in 12-15-year-olds, and the federal government has given the green light for the vaccine rollout across this age group from mid-September.
Approval for the Moderna vaccine in this age group is still pending, awaiting results of clinical trials, according to the Australian Technical Advisory Group on Immunisation.

Covid infection increases the risk of venous thromboembolism 13-fold, compared to a 10% increase following the AstraZeneca vaccine.
A study published in the BMJ compared the risks of thrombocytopenia and thromboembolism with covid infection to the risks after receiving either the AstraZeneca or Pfizer vaccine.
This revealed that the AstraZeneca vaccine was associated with a 33% increase in the risk of thrombocytopenia in the 8-14 days after vaccination, but a positive SARS-CoV-2 test was associated with a 5.2-fold increase in risk.
The risk of arterial thromboembolism was 6.5-fold higher among people testing positive to SARS-CoV-2 but 6% higher among those who received the Pfizer vaccine.
Individuals receiving the AstraZeneca vaccine had a four-fold increase in the risk of cerebral venous sinus thrombosis, but the risk was nearly 18-fold higher after a positive SARS-CoV-2 test.
The risk of ischaemic stroke was nearly four-fold higher after a positive test compared to 12% higher after receiving the Pfizer vaccine.
“The incidence rate ratios associated with SARS-CoV-2 infection were much higher for each outcome than those associated with either vaccine, with the greatest risk for all outcomes being in the first week after a positive test,” the authors wrote.

The risk of thrombosis with thrombocytopenia associated with the AstraZeneca in Australian is 2.6 per 100,000 doses in those aged under 60 years, and 1.8 per 100,000 doses in those aged 60 years or older, according to the latest update from the Australian Technical Advisory Group on Immunisation.
Australia has now recorded 116 cases of confirmed or probable TTS and six deaths, from around 8.8 million doses of the AstraZeneca vaccine. The case fatality rate in Australia – around 5% – is significantly lower than that seen in the UK, which is around 18%.
There have also been 235 reports of suspected myocarditis and/or pericarditis after receipt of the Pfizer vaccine, ATAGI reported, but most are mild and self-limiting.

Sick of answering questions about ivermectin? Australia’s National Covid-19 Clinical Evidence Taskforce has you covered, with a detailed Q&A about ivermectin now available.
And, in case it needs repeating, the Taskforce strongly advises against the use of ivermectin outside of randomised clinical trials.

Young people – and particularly primary-school-aged children – are gaining weight during the pandemic at a greater rate than before the pandemic, research suggests.
A retrospective cohort study published in JAMA compared BMI of more than 191,000 children aged between 5-17 years who had their BMI measured in the year before the pandemic and again in the first year of the pandemic.
The number of overweight or obese 5-11-year-olds increased from 36% to 45% during the pandemic – an absolute increase of nearly 9% – while among 12-15-year-olds it increased by just over 5 percentage points and among 16-17-year-olds it increased by just over 3 percentage points.
Children aged 5-11 had a median BMI increase of 1.57, compared to 0.91 among those aged 12-15 years and 0.48 among those aged 16-17.

Here are the latest covid infection numbers from around Australia to 9pm Sunday:
National – 51,256 with 999 deaths
ACT – 374 (13)
NSW – 24,585 (1213)
NT – 201 (0)
QLD – 1978 (1)
SA – 871 (0)
TAS – 235 (0)
VIC – 21,926 (92)
WA – 1086 (0)

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