There’s more data about reinfections now, and it looks like some get it worse on reinfection. FDA, if it’s found they are intentionally delaying Leronlimab’s availability, will be faced with no choice soon, I believe.
https://www.theguardian.com/world/2020/oct/06...ts-puzzled
https://www.theguardian.com/world/2020/oct/06...ts-puzzled
Quote:
Many researchers took heart from the case, but since the patient came to light a flurry of reinfections around the world have raised fresh concerns. Within days of the Hong Kong case being made public, doctors in the US reported that a 25-year-old man from Reno, Nevada, had been hospitalised with a Covid-19 reinfection after shrugging off an earlier brush with the disease. More cases soon followed. While most infections were no worse the second time around, a good number cropped up – in the US, the Netherlands, Ecuador and India – where the reinfection was more severe.
In a report on reinfected healthcare workers in India, Prof Jayanthi Shastri and her team at Kasturba hospital for infectious disease in Mumbai describe a 25-year-old nurse who suffered more with a reinfection two months after her first battle with coronavirus. “Her immunity wasn’t enough to protect her from the second, more severe infection despite the presence of neutralising antibodies,” Shastri said.
The finding, and similar cases, has refocused attention on a handful of questions that scientists are struggling to answer. What does protective immunity look like? How long does it last? Do some patients fail to mount the right response? Does the virus damage the immune system? And are reinfected people infectious to others?
Danny Altmann, professor of immunology at Imperial college in London, guesses that those who recover from Covid-19 will have perhaps 90% protection for a “fair while”. But how long is that? “I would bet my house on you being safe for possibly a year but not much longer,” he said. “The problem is that whenever an immunologist says anything about Covid immunity to a journalist, it’s right for about two weeks and then it’s completely wrong.”
Reinfections may be worse for a whole host of reasons. The person might have been exposed to more virus the second time around, or may simply have been under the weather already when the virus struck again.
Another possibility is so-called antibody-dependent enhancement – a glitch in the immune system where antibodies help an invading virus rather than hinder it. This is seen in dengue fever where second infections can be far more dangerous than the first.
Yet another possibility is that the virus harms T-cells, in some patients at least. “We need to study the T-cells,” said Swapneil Parikh, who worked with Shastri on reinfected hospital workers. “Is the virus doing something to the immune system that is setting you up for more severe infections?”
The virus can certainly disrupt the immune system. In August, Shiv Pillai, an immunologist at the Ragon Institute of Massachusetts general hospital, examined tissue taken from dead Covid-19 patients. He looked for structures called “germinal centres” in the spleen and lymph nodes. These are where B-cells go to develop antibodies before they are stored in the immune system’s memory. Pillai failed to find any, suggesting the patients were unable to generate highly effective, long-lasting antibodies that would fight the virus for years.
He believes the same problem may arise in people with milder Covid-19 too. “If we want antibodies that will persist for a few years and protect us, it’s not clear that’s going to happen,” he said. The good news is that a vaccine should not cause the same problem as the virus. “I don’t see why the vaccines won’t work. They may not be fantastic, but I believe that’s what’s going to protect us,” he said.
If the virus spreads further through the autumn and winter, Iwasaki expects to see more reinfections, with some patients infectious enough to pass the virus on.
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