The most burning 🔥 Questions right now:

Will #SARS2 continue to mutate to escape antibody protection? Do we need another booster? If so, what’s the next formula? For example, do we need an Omicron-specific vaccine?
1/
By the time an Omicron-specific vaccine is tested, we won’t have an Omicron wave anymore. So, is there still value in rolling it out? 2/
It all depends on how the SARS2 keep on evolving? The problem is it’s not following a fixed pattern. We know about evolutionary features of two viruses namely #flu and #measles. 3/
The new #flu vaccine formula is fairly predictable, because the virus mutates in a ladder-like pattern: there is one major lineage, and every few years, a new variant sweeps and the others go extinct. 4/
On the other end of the spectrum is #measles (B). While measles mutates, it does not mutate to escape immunity. It has a more balanced evolutionary tree 5/
#Measles There is no immune pressure that constantly pushes one mutation to outcompete another. So there is no ladder-like pattern. And, thankfully, our vaccines from the mid-1960s still work today. 6/
But the flu and measles are very different from #coronaviruses. To understand how SARS2 may change to escape immunity over time, we must look at other coronaviruses that have been circulating for decades. 7/
Take the case of this common cold #CoV229 that has been circulating since at least the 1960s. It has also evolved over time. The CoV229E is probably a good indicator of what’s to come with SARS2 because the viruses look fairly similar. 8/
#CoV229E mutated over time in a clear ladder-like pattern, just like the flu
Over time, mutations of CoV229E eroded antibody protection. In other words, people that were only infected by CoV229E in 1984 weren’t well protected today. 9/
This tells us that we should expect a ladder-like evolution of #SARS2 through which we could predict the next variant.
However, much to our surprise, this hasn’t happened. 10/
#SARS2 has thrown us for a loop, as the mutations haven’t evolved in a ladder-like fashion. The next variant hasn’t been coming from the last: Omicron didn’t come from Delta, and Delta didn’t come from Alpha. 11/
The fact that #SARS2 has lacked a pattern of evolution like other coronaviruses or the flu is incredibly puzzling. 12/
But, we haven’t had a lot of time for this pattern to play out. It’s only been 2 years and other evolutionary trees, like #CoV229E, also had 2-year time frames in which there were no ladder-like changes. 13/
Most experts expect the ladder-like pattern to arise with #SARS2 eventually. But because it hasn’t yet, we don’t know which direction SARS2 is heading. This makes proactively predicting the next booster formulas challenging and risky. 14/
Do we need another booster right now?
There are really two camps of thought right now:

1-There is not enough evidence that we need another booster. Boosters are working fantastically well against severe disease during the Omicron wave. 15/
2-Roll-out another booster vaccine. Just like what #Israel is doing. Israel already rolled out a second booster (not Omicron specific formula) among those aged 60+ years. 16/
Bottom Line:

It's tough to make predictions, especially about the future.” And #SARS2 is making it even more difficult with its random evolutionary patterns. 17/

journals.plos.org/plospathogens/…

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More from @vipintukur

Feb 1
It’s a delusion to think mass spread of Omicron will end the pandemic

The idea that herd immunity from widespread Omicron infection will last longer than a few months is a mass delusion propagating in all forms of media. 1/
It’s the type of delusion sure to gain traction in a world where we are all absolutely sick and tired of the pandemic. It even ignores reality from three months ago, when Omicron didn’t exist and the idea of us benefitting from infecting everyone was a widely condemned idea. 2/
The reality is we are causing COVID-19 to mutate on a scale never seen before. By allowing the virus to infect much of the world, we are generating trillions upon trillions of viruses. 3/
Read 10 tweets
Feb 1
The possibility of using animal-adapted variants to develop a multivalent SARS-CoV-2 vaccine, such as that for the vaccinia virus for smallpox.

medrxiv.org/content/10.110…
In fact, a half-adapted mink variant was barely able to spread among humans. It probably had low virulence and was quickly replaced by a more infectious variant.
A more adapted variant would probably not be able to spread from humans to humans. Once a weakly toxic variant is selected, it can be maintained and propagated in its host and cultured cells.
Read 4 tweets
Jan 31
People are being reinfected immediately again after #Omicron infection!!

A new study shows that immunity based upon “mild" Omicron infection is weak for Omicron reinfection, and limited for cross immunity to Delta infection. 1/
Overall, immunity from Omicron infection is much lower than the immunity from Delta infection, correlated with the severity of infection. 2/
What does that mean?
Unless you get a severe infection with all of its consequences you also don’t get immunity from having another infection.
And recall even immunity from severe infection wanes rapidly in a few months. 3/
Read 5 tweets
Jan 31
Transmission of SARS2 #Omicron’s subvariants BA.1 & BA.2

A Danish households transmission study

➡️ The secondary attack rate was estimated as 29% and 39% in households infected with Omicron BA.1 and BA.2, respectively. 1/
➡️ BA.2 was associated with an increased susceptibility of infection compared to BA.1.

-Unvaccinated (Odds Ratio (OR) 2.19; 95%-CI 1.58-3.04),
-Fully vaccinated (OR 2.45; 95%-CI 1.77-3.40)
-Booster-vaccinated (OR 2.99; 95%-CI 2.11-4.24). 2/
➡️ There was an increased transmissibility from unvaccinated primary cases in BA.2 households when compared to BA.1 households, with an OR of 2.62 (95%-CI 1.96-3.52). 3/
Read 8 tweets
Jan 30
Last night, renowned Indian virologist, Dr T Jacob John predicted that the pandemic would end in the spring of 2022 & the #Omicron is probably the last VOC! Let’s see what are the other views on these issues. 1/
Making predictions is a risky thing. More so with the SARS2. Perhaps we know enough now to know we shouldn’t try to predict anything about this virus! 2/
No, the SARS2 has not stop evolving, and the #Omicron isn’t the last VOC. We are already witnessing its intense evolution in form of sister lineages like BA.2 & BA.1.1 which are quite distinct & distanced from the Omicron 3/
Read 28 tweets
Jan 29
COVID vaccine #boosters are proving a useful tool against Omicron, but many believe that endless boosting might not be a practical or sustainable strategy. 1/
Because protection from boosters might be short-lived, rolling out endless doses — potentially at the expense of immunizing unvaccinated people in low-income nations — is not a “viable or reasonable” long-term global strategy. 2/
Then, what are options?
1-Continue to go for repeated boosting at regular intervals
2-Develop new vaccines. What are the options:
a. Variant-specific vaccines
b. Pan-coronavirus vaccine (pansarbecovirus vaccine, at least) 3/
Read 4 tweets

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