Alina Chan Profile picture
Jun 22, 2021 24 tweets 9 min read Read on X
On Singapore’s recent delta variant covid cluster: “The cluster’s index case, Case 62873, is an 88-year-old cleaner who worked at Changi Airport Terminal 3. He tested positive on May 5 despite being fully vaccinated.”
channelnewsasia.com/news/singapore…
Another delta cluster in Singapore at a hospital: “A fully vaccinated 46-year-old female nurse at TTSH, or case 62541, became the first case linked to the cluster after she tested positive on Apr 27.”
“In the Delta variant clusters, Prof Leo has seen vaccinated cases with family members who have tested positive. This means it could still be possible for vaccinated people to spread the virus.”
“The experts stressed that new variant strains arise when viruses evolve to adapt and evade human defences”

“Disorganised, half-hearted attempts are exactly the prescription for viral mutants.”
Singapore’s tracking of covid cases is incredible. It’s only when you can clearly follow the chains of transmission that you can understand whether a new variant can infect and be spread by vaccinated individuals (only Pfizer and Moderna in Singapore btw).
The good thing is that full vaccination still confers protection against new variants, even if efficacy is slightly reduced. So it’s very important for people in high risk groups to get vaccinated, especially in places where there are low vax rates and new variants circulating.
For example, did any of the fully vaccinated airport workers who still got infected with the Delta end up transmitting it to other people?
In India:
“from his experience, he said patients with “reinfections have not landed in the Intensive Care Unit.”
vice.com/en/article/epn…
Very useful covid tracking app for Singaporean cases
h/t @romeo_ph20
covid.viz.sg
@romeo_ph20 Looking at the Bukit Merah market cluster, you can see (if the data is indeed correct) that some vaccinated people are transmitting covid / SARS2 to other people.

Green = fully vaccinated (pfizer/moderna)
Yellow = 1 dose

The selected (blue) vaccinated person is 23 years old. Image
@romeo_ph20 The selected vaccinated person in this cluster is 39 years old. A chef working at Changi prison. Image
36 year old dealer at Marina Bays Sands Casino Image
18 year old national service man at the Civil Defence Academy Image
The site also tells you who was asymptomatic or symptomatic when they tested positive for covid-19.
For example, in this mini-cluster of 3 fully vaccinated people, the connector person was asymptomatic. Image
The purpose of getting vaccinated is preventing severe disease/death. And when your community has high vaccination rates, the likelihood of clusters is diminished. This protects the elderly/vulnerable who may not be fully protected even after vaccination.
This Covid-tracking app in Singapore is super useful for understanding how transmissible the virus is among vaccinated individuals.
Green = 2 doses
Yellow = 1 dose
The central person is 35 years old. This looks like a workplace cluster. 3 fully vaxed people transmitted to others. Image
I'm not too worried about vax'ed people being infected because ideally the vaccine would've protective effect. But I'm worried about the people who distrust the healthcare system and refuse to get vax'ed. The virus can spread via vax'ed people. covid.viz.sg
Wanted to give a shoutout to our own site @CovidCg covidcg.org you can track the lineages and variants in each country over time.

For example, Singapore, delta / B.1.617.2 is shown in light blue.
covidcg.org/?tab=group&gro… Image
In the USA you can see the % of sequenced SARS-CoV-2 that are the delta / B.1.617.2 / Indian (light blue) have also been growing, displacing the alpha / B.1.1.7 / UK (dark blue) over time. Gamma / P.1 / Brazilian is in green. Image
Not as striking as the UK. Delta has completely overtaken Alpha. Image
Plotting similar data for other countries, but measured in counts (like for Singapore above) as opposed to % (US and UK above).

Australia, Japan, S Korea, S Africa. ImageImageImageImage
Another way to use covidcg.org is to plot the new % of sequences that are delta variant per month in each country of interest.

For example, in Singapore, 94% of the June sequences were the delta variant. UK 92%, Australia 60%, Japan 46%, USA 23% etc. Image
Switching the plot to show the new % of sequences that are the alpha variant per month. Image
The beta variant. Image

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More from @Ayjchan

Jan 9
No punches pulled piece on #OriginOfCovid by @ianbirrell

"The pandemic revealed the arrogant and contemptuous behaviour of leading scientific figures, aided by prominent academic journals, patsy journalists and weak politicians."
unherd.com/2025/01/chinas…
@ianbirrell I suggest one correction @ianbirrell please replace 'despite' with 'because of':

WHO "hired Sir Jeremy Farrar, despite the former Wellcome Trust boss’s exposure as a central player in... branding any suggestions Covid could have come from a laboratory as conspiracy theory."
@ianbirrell On Feb 19, 2020, the authors of Proximal Origin realized that Jeremy Farrar - who had convened them and led their efforts - had signed the Lancet letter by Daszak condemning all lab #OriginOfCovid as conspiracy theories. Image
Read 5 tweets
Jan 5
5 years ago, the authors of Proximal Origin wondered where the pandemic virus had been transmitting *intensely* so that it gained a furin cleavage site and passed it on.

One said, "No way the selection could occur in the market. Too low a density of mammals." #OriginOfCovid Image
Until today, there has been no reported sign of intense transmission of the virus in animals prior to the detected outbreak in Wuhan.

Investigators, including one Proximal Origin author, searched fur farms in China - no sign of any SARS-like virus.
nature.com/articles/s4158…
On the other hand, a 2018 research proposal surfaced, showing Wuhan and US scientists with a plan to insert novel furin cleavage sites into novel SARS-like viruses.
theintercept.com/2021/09/23/cor…
Read 8 tweets
Jan 1
"5% chance that H5N1 starts a sustained pandemic in humans in the next year. 50% chance that H5N1 starts a sustained pandemic in humans in the next twenty years..."

I invite @slatestarcodex to estimate the chances of a lab-based flu pandemic by 2025!
astralcodexten.com/p/h5n1-much-mo…
@slatestarcodex For consideration, only 4 projects have been flagged by NIH for HHS review since 2017.

One project, funded till 2020, proposed creating ferret transmissible H5N1.

One project, proposed in 2024, was not funded by NIH so no info was made public.
aspr.hhs.gov/S3/Pages/Resea…Image
@slatestarcodex In addition, under the new US gov policy on research that enhances the pandemic potential of pathogens, it will be the funding recipient (not the funder) who is responsible for flagging their own federally funded projects for review.
liebertpub.com/doi/abs/10.108…
Read 5 tweets
Dec 23, 2024
Peter Daszak, who partnered with the Wuhan lab that likely caused the pandemic and is being debarred by HHS, continues to chair @NASEM_Health's forum on microbial threats.

Daszak's forum is hosting @theNASEM workshop on the future emergence of pathogens.
nationalacademies.org/event/43921_01…
@NASEM_Health @theNASEM The event disclaimer and website make no mention of Daszak's involvement in this event or any conflicts of interest. Image
@NASEM_Health @theNASEM This echoes Daszak's behind-the-scenes coordination of the infamous letter in @TheLancet casting lab #OriginOfCovid as a conspiracy theory without disclosing his conflicts of interest.

Read the story about this letter in @theintercept
theintercept.com/2021/09/23/cor…
Read 7 tweets
Dec 22, 2024
In 2020, leading virologists deceived a @nytimes journalist, resulting in NYT dropping the lab leak hypothesis.

Years later, these virologists continue to deny their perfidy while attacking experts like @sigridbratlie who call out their deception.
telegraph.co.uk/us/news/2024/0…
@nytimes @sigridbratlie At the @USFHealth Covid meeting, natural #OriginOfCovid proponents exalted one of these virologists.

Thankfully @ewinsberg read out the slack messages of these virologists which completely contrasted with their public stance.
@nytimes @sigridbratlie @USFHealth @ewinsberg Some consider the lies of leading virologists as indirect evidence for a lab #OriginOfCovid e.g. see the end of this anonymous analysis on youtube.

Why are some smart virologists making so many claims they should know are false?
Read 6 tweets
Dec 22, 2024
I gave a 15min talk on a likely laboratory #OriginOfCovid at @USFHealth's @HdxAcademy meeting on hotly debated Covid topics earlier this month. The exchange with natural origin proponents and Q&A are worth watching. The recording is available now: digitalcommons.usf.edu/usfcovid/2024/…
@USFHealth @HdxAcademy The meeting covered other topics including lockdowns, vaccines, and public health messaging. I left the meeting with my mind changed on one topic - a sign of high quality scientific exchanges on issues that remain unresolved.
@USFHealth @HdxAcademy Several talks recalled the panic in the early days of the pandemic, especially in hospitals overwhelmed by covid cases. In crisis, public health decisions & messaging were often developed in echo chambers and not based on science.
Read 9 tweets

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