This is a pre-print, and needs to be interpreted carefully, but if it's correct the implications are concerning.

From about mid-2020, SARS-CoV-2 began to evolve at a faster rate, and is now evolving faster than influenza. Whether this will continue is unclear.
The authors suggest two theories for this, both of which could be true.

First, certain mutations could "unlock" new space for further mutations to occur. This seems quite likely: the virus has only just started to adapt to humans
Second, selection pressure could be driving an increase in mutations. Think of the first wave in Manaus, Brazil, where people thought herd immunity had been reached. A second wave followed, as the virus evaded immunity and got better at infecting people.
This study clearly illustrates the danger of allowing very high levels of transmission to continue. SARS-CoV-2 could continue to become more transmissible, which would make control very difficult.

The delta variant is unlikely to be the worst we see.
It seems likely that our current vaccines will become less effective, and variant-specific boosters will be required. This would pose serious challenges for the developing world, which already lacks access to vaccines.

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More from @DrZoeHyde

26 Aug
For those overseas wondering what’s going on in Australia, we have NOT given up on zero COVID.

All states and territories, except one, continue to try to suppress the virus while we vaccinate.

Incredibly, the government of NSW has gone rogue and is pushing a UK-style approach.
In contrast to other parts of Australia, the NSW government refused to lockdown when the delta variant was first detected in the community, and implemented restrictions only grudgingly.

The contrast between NSW and where I live speaks volumes.

We have no known transmission.
Unfortunately, I fear the negligence of the NSW government will affect us eventually.

It will be harder to keep COVID-19 out now, and we still have many people to vaccinate.

This is the second major problem we face. Our cheapskate federal government didn’t buy enough vaccines.
Read 4 tweets
23 Aug
At what level of vaccination can Australia safely reopen?

With 70% of adults vaccinated, expect:
📈 6.9 million cases
🏥 154,000 hospitalisations
☠️ 29,000 deaths

At 80%:
☠️ 25,000 deaths
🤒 270,000 people with long COVID

We need >90%, including children, to be safe.
Children & adolescents must be included to reopen safely. If we don’t vaccinate them we can expect thousands of deaths from vaccine breakthrough infections.

Children also benefit directly from vaccination.

75% vaccination in children would prevent 12,000 child hospitalisations.
These figures are the results of new modelling produced by @GraftonQuentin, @Tom_Kompas, John Parslow, & me.

We explored what would happen when the final stage of the National Plan is reached, where it’s proposed to manage COVID-19 like flu.

Read more:…
Read 21 tweets
21 Aug
Study of vaccine effectiveness in New York (51% received Pfizer-BNT, 40% Moderna, and 9% J&J). Protection against symptomatic infection decreased over 3 months from 92% to 80% (likely delta variant effect) but hospitalisation protection maintained at ~95%.…
During the course of the study, the prevalence of the delta variant increased from <2% to more than 80% in the area in which the study was conducted.

This seems like the most likely reason for the decrease in effectiveness against symptomatic infection.
This study demonstrates the importance of continuing public health measures, such as improving ventilation and using masks in public places, until very high levels of vaccination are achieved in the population.
Read 6 tweets
10 Aug
I'm shocked this piece was published. Not because I disagree, but because it contains statements which are misleading or inaccurate.

Do you think children should be offered vaccination?

Please vote in the poll accompanying the article, and leave a comment on the website.
The authors state about 2 per million children have died in England, but the denominator is the entire population!

Correcting for virus exposure, the death rate is 5 per 100,000.

One of the authors knows this because they analysed these data! @MJA_Editor…
The authors also state that "[r]outine vaccination of well teenagers aged 12–15 years adds little to the reduction in COVID-19 transmission through the community."

This is false.

While there is some debate about how much children transmit, adolescents transmit just like adults.
Read 6 tweets
3 Aug
Sending students back to school in the midst of a growing delta variant outbreak is one of the worst things you can do.

Schools are a major driver of community transmission.
Spacing students apart in the classroom helps, but isn’t sufficient because the virus that causes COVID-19 is airborne.

This means it spreads through the air like cigarette smoke, and can linger in a room long after an infectious person has left.
Making schools safe requires a comprehensive package of measures, including the use of face masks and improved ventilation.

Ideally, students & staff should also be vaccinated, but remember that people aren’t fully protected until after the second dose.
Read 4 tweets
29 Jul
In this small study of 39 breakthrough cases, 7 of 36 (19%) followed for 6 weeks got long COVID.

⚠️This may be an overestimate as asymptomatic breakthrough infections were likely missed in the full sample of 11,453 people.

However, it shows vaccinated people can get long COVID.
It’s also important to remember that these people first had to get infected and become a breakthrough case before they were at risk of developing long COVID.

Developing long COVID after vaccination is probably uncommon (but not rare).
The risk of becoming infected after vaccination should decrease as more of the population is vaccinated. Even if herd immunity isn’t reached, there should be some herd protection.

But until transmission is brought to low levels, it would be a good idea to keep wearing a mask. 😷
Read 4 tweets

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