Something interesting about the Brazilian and Californian mutations:
https://www.statnews.com/2021/01/19/cor ... infection/
It's no surprise it was the first city in the world for a significant proportion of the population to be contaminated, and that the cases have started rising yet again.
https://www.statnews.com/2021/01/19/cor ... infection/
Manaus is one of the worst cities in the world for a pandemic to arise. Very high population density, most of the population lives in squalid conditions and can practice no social distancing, and since it is in the middle of the Amazon, people depend on ferry boats to move around which are densely packed.A recent study estimated that three-quarters of residents of the city of Manaus, Brazil had been infected by SARS-2 by October. The hope was that this level of protection might act as a buffer against more transmission. But last month, cases started rising in the city and its state of Amazonas, straining local health systems once again.
When researchers dug into the viral sequences, they found many cases involved a new variant, called P.1, as reported last week. (P.1. has also been identified in people who traveled from Brazil to Japan.) They warned the mutations it contained (including E484K) are “potentially associated with an increase in transmissibility or propensity for re-infection of individuals.”
Scientists suspect there are several potential factors at work in Manaus, which could be playing out together. They’re investigating.
Maybe P.1 is indeed able to evade some existing immune protection, leaving people more susceptible to reinfection. Scientists on Sunday confirmed a case of reinfection caused by P.1 in Amazonas.
Or perhaps P.1 is so transmissible that it can spread just fine even in communities with 75% protection.
Or what if some people in Amazonas who were infected months ago are just generally becoming susceptible again to any form of reinfection, regardless of variants? Though immune responses vary, it’s thought that most people who fend off the virus will have lasting protection for some time — but that it will wane. Already, some reinfections have been reported around the world, without the involvement of more transmissible variants. (It’s thought that reinfections with SARS-2 will generally be milder for most people than their initial case because they still have some immune memory to the virus, even if their systems couldn’t block infection entirely. Scientists will be looking out to see if that holds with different variants.)
What are scientists doing about all this?
Studying it from all angles. One line of inquiry is examining the effects of mutations in isolation and in concert with the other changes dotting the virus’ RNA genome. Essentially, a mutation on its own may not have much of an impact, but it can help a virus spread better or replicate faster if it’s paired with certain other mutations.
Related: Are more people surviving Covid-19 because doctors are doing less?
Scientists are also on the lookout for other potential variants of concern as they comb through sequencing data. But there’s a sense among some experts that new variants are being announced without much helpful information. Lots of mutations will be discovered; it can take some time to figure out what, if anything, each one means.
In California, for example, officials held a press conference Sunday to discuss the L452R variant, which has grown from accounting for 3.8% of samples sequenced in the state in the first half of December to 25.2% of sequences heading into January. “We do not know whether it’s more infectious yet,” UCSF virologist Charles Chiu said, though he added, “it is concerning that it may potentially be more infectious.”
Outside experts were quick to say that more evidence is needed before such a claim can be verified. The variant was first seen in California in May, and hovered at low levels while the state was at low levels of virus overall. Then, it started to increase as the state was suffering from major outbreaks. This can create the illusion that the variant — because it’s so much more prevalent — was perhaps driving the cases. But without more data, it’s just as likely the variant didn’t cause the wave, but simply “went along for the ride,” Goldstein said.
It's no surprise it was the first city in the world for a significant proportion of the population to be contaminated, and that the cases have started rising yet again.