Thread by @vinodscaria

While #SARSCoV2 infections surge once again across the world, a short and continuously updated 🧵 on the BA.4 /BA.5 variants.

Have written in quite detail about the variants in the past. thehindu.com/sci-tech/will-…

Briefly, the variants were identified - thanks to the researchers in South Africa 🇿🇦 who have been using genomic surveillance quite efficiently. We knew about these two variants as early as April 2022 as cases were slowly increasing in SA just after the omicron wave.

BA.4 and BA.5 are subvariants of Omicron which was the most recent VoC . The rapid spread of omicron across the world has created a large number of subvarinats- each characterised by specific combination of mutations. BA.4 and BA.5 are interesting in many ways.

⚪ Immune Escape
The variant can infect individuals who had immunity against #SARSCoV2 from previous infections or vaccines. It is thought that the L452R mutation in spike could contribute significantly to this.
ESC has details about the mutation clingen.igib.res.in/esc/

⚪ Fusogenicity
BA.4/BA.5 variants seem to apparently have better fusogenixity in experimental laboratory models . Data from @SystemsVirology has been key in this regard
biorxiv.org/content/10.110…

🔴 Does this impact everyone the same way ?
Apparently NO.
There seems to be more we dont yet understand on what influences the severity (deaths/hospitalisation) in a region wrt another.

For example, the BA.4/BA.5 wave did not cause much of an issue in South Africa. @rid1tweets has a wonderful comparison 👇

https://twitter.com/rid1tweets/status/1534216690145320966?t=YNaklYcMK0LSvum8WiNmTw&s=19

While in Portugal 🇵🇹, it caused a wave as much as the precious Omicron wave (BA.1/BA.2) with significant and comparable mortality

https://twitter.com/chrischirp/status/1535280947146399746?t=iQhevdICAxbc9KkuMm9vGA&s=19

Now what does that mean to containment efforts?
We need to keep in consideration
1. Prior immunity is likely not protective
2. Proportion of at-risk individuals in population
3. Almost cyclical nature of waves of infection- in the past and also expected on future.

🔴 we do have many very effective non- pharmacological interventions at hand
MASKS - good quality (like N95) masks are quite effective in preventing infections. So continued mandates are possibly needed for a longer term, especially for high risk people.
So better and more masks

VENTILATION- even small efforts to improve ventilation could significantly reduce the risk of infections. Places where crowding is unavoidable and ventilation is not effective, air filters could be mandated - as in halls, malls, etc.

Sorry for the typo. 👆To be read as #previous

🔴 Until we have newer generations of vaccines (which I don't see widely being available across the world due to existing inequities) MASKS and VENTILATION are our best and effective alternatives to keep the infection at bay.

Avoiding infections are indeed important, to avoid associated morbidity
⚪ The infection might be apparently mild, but with long term insult to your body.

Pulling in a recent discussion 👇

https://twitter.com/vinodscaria/status/1539555364831518720?t=UyeOCBCr-GdUwIxY4dSDag&s=19

🔴 What about India 🇮🇳?
BA.4 /BA.5 has been identified in India and going by data in public domain, increasing in many states.
An effective, consistent genomic surveillance system can uncover trends . We could learn a lot from around the world and within the country.

🔴 There is little / no data in public domain from many regions in India having an ongoing active wave of infection. So assessment of what are driving these waves is not possible at the moment.

https://twitter.com/jburnmurdoch/status/1541097827954311168?t=mBy3fZNN3fL70uL6JwfoUg&s=19