Here’s some good news. In this study of 514 people who received their first Pfizer vaccine dose, those who’d previously been infected showed a superior immune response compared to uninfected people, even if initial antibodies were no longer detectable.
eurosurveillance.org/content/10.280…
Research has already shown that the vaccine acts like a super-booster in people who’ve been infected with SARS-CoV-2, suggesting that one dose may be enough for them.

However, it wasn’t clear if this would still apply if the antibodies from infection were no longer detectable.
This study shows that everyone got a boost, even if they no longer tested positive for antibodies.

A limitation is that the study only had 17 people with a previous infection (6 with detectable antibodies, 11 without), but the results are still reassuring.
One of the people who’d previously been infected was infected 10 months before vaccination.

Despite this 10-month gap, they still experienced a boost effect. This suggests immunity could be long-lived in some people. How many people? We don’t yet know. But it’s a promising sign.
This study may interest you, @Kaethelin. I remember you asking me a question about something related to this.

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More from @DrZoeHyde

8 Feb
Thread summarising an important presentation on the AstraZeneca trial results for South Africa.

Key points:

➡️ Efficacy initially seemed to be ~75%, but dropped to 22% against SA 🇿🇦 variant.
➡️ Past COVID-19 (original) doesn't protect against reinfection by the SA 🇿🇦 variant.
This was a relatively small trial with only 1,749 mostly young, healthy participants.

People were given two doses of the vaccine about 28 days apart.
The relatively small number of people in the trial makes it suitable for exploring the efficacy of the Oxford/AstraZeneca vaccine against mild-to-moderate disease only.

The trial lacks statistical power to tell us the efficacy of the vaccine against severe disease.
Read 19 tweets
7 Feb
Australia must now reconsider its plan to use the Oxford/AstraZeneca vaccine, and instead use a high-efficacy vaccine like Novavax.

We've an agreement for 51 million doses of Novavax and can manufacture it domestically.
#auspol #COVID19Aus
amp.ft.com/content/e9bbd4…
According to preliminary results seen by the Financial Times, the Oxford/AstraZeneca vaccine does not appear to prevent mild and moderate COVID-19 caused by the South African variant.
While the company believes the vaccine may still prevent severe disease, there are now question marks as to whether it will be sufficient to prevent the debilitating condition known as long COVID, which is common even in mild disease.
Read 5 tweets
6 Feb
Study describing the incidence of PIMS/MIS-C in South Korea. From May to November 2020, 2,287 COVID-19 cases were detected in children. During this time, 3 serious MIS-C cases occurred, equating to an incidence of approximately 1 in 800 children.
wwwnc.cdc.gov/eid/article/27…
South Korea has largely suppressed COVID-19, and has excellent testing and contact tracing.

While it’s likely they missed some SARS-CoV-2 infections in children (which would overestimate the incidence), they probably missed some mild MIS-C cases (which would underestimate it).
Therefore, 1 in 800 is probably the upper bound for the true incidence of MIS-C.

Assuming a worst-case scenario, where there were actually 5 times as many SARS-CoV-2 infections in children than detected, the lower bound would be 1 in 4,000.
Read 6 tweets
5 Feb
Important pre-print study (but from a good team, including @florian_krammer), showing a single dose of a mRNA vaccine may provide superior protection to two doses, in people who’ve already had COVID-19. This could free up the vaccine supply, enabling more people to be vaccinated.
The researchers found that when people who’d previously been infected were given a single dose of a mRNA vaccine, their resulting antibody titres were 10-fold higher than people who hadn’t been infected, but received two doses of a mRNA vaccine.
The researchers also found the side effects of the vaccine were more pronounced in people who’d previously been infected (though none were serious).

Thus, if these people only need to be given a single dose of the vaccine, this could potentially save them unnecessary discomfort.
Read 4 tweets
2 Feb
(1/6) This is quite a concerning development. An additional mutation (E484K; a key mutation in the South African variant) has now also been detected in a limited number of people infected with the UK variant.

Laboratory experiments suggest vaccine efficacy may be reduced.
(2/6) Here’s a nice figure from @K_G_Andersen, showing the different mutations in the UK, South African, & Brazilian variants.

E484K has now also appeared in multiple people in the UK, suggesting a process of convergent evolution. This means it’s likely to happen elsewhere, too.
(3/6) So far, this enhanced UK variant has been detected in 11 of 214,159 samples tested.

The E484K mutation previously appeared in a cluster of 32 cases of the original strain in Liverpool.
bbc.com/news/health-55…
Read 6 tweets
31 Jan
Case report of a hospital COVID-19 outbreak probably caused by airborne transmission. A child with an infected mother was admitted, after which 6 healthcare workers, 2 child patients, and 1 parent tested positive.

H/T: @CPita3 via @lisa_iannattone.
academic.oup.com/ofid/advance-a…
Three of the 6 healthcare workers had no direct contact with the mother or child and maintained a distance of approximately 2 metres during a ward round and dietician consultation. All 6 wore surgical masks. No aerosol-generating procedures were performed.
An additional 3 out of 4 contacts (2 child patients and one mother staying in the same room) tested positive. They were staying at a distance of more than 2 metres from one another, although brief contact over a shorter distance cannot be ruled out.
Read 11 tweets

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