Paul writes:

TWIV Crew,

Thanks so much for having Dr. Offit on the show – he’s one of my favorite, repeat guests.

The Omicron specific booster for the Fall is a critical issue, and not for the obvious reason.  Public health needs to get a “call,” right.

Unfortunately, public health has done a less than stellar job educating the public about Covid vaccines, so far.  From over playing the initial 94% efficacy against symptomatic infection and promises of greatly reduced spread, public health’s message has had to be continually re-calibrated toward a more realistic outlook – SARS Cov 2 vaccines, like most vaccines, are meant to prevent severe disease and death.

Unless told otherwise, most Americans will assume that a variant-specific vaccine will offer noticeable efficacy over the original – I’ve even read comments from virologists indicating this belief.  The general public doesn’t understand somatic hypermutation, affinity maturation and immune imprinting.

I had hoped that TWIV 917 would have covered these topics more in depth.  Some may consider these phenomena too complex for the general public, but without understanding each, the public will never grasp why an Omicron specific vaccine may only offer minimal benefit over the wild type.

Dr. Offit mentioned that he considered the mRNA vaccines a 3 dose treatment, and that the 3rd dose greatly increased breadth.  Although true, it’s misleading to not explain why.  

It’s not something magical about a 3rd shot. It’s that the third shot, as an immunological challenge, turns on the hyper mutated, quiescent, memory B cells that the body created over the preceding 6 months or more, since the first immunizations.

Through hypermutation and affinity maturation, the body creates such breadth and quality within memory B cells, that an Omicron specific challenge may not bring significantly more to the immune repertoire. Further, immune imprinting might partially limit additional breadth in future, immune memory.

Perhaps there will be additional somatic hypermutation after an Omicron specific immunization, but this is unknowable at the moment.

Public health needs to better educate the public about SARS Cov 2 vaccine immunology and take a more pragmatic stance on the potential benefit of an Omicron specific vaccine, or risk a continued erosion of credibility with the general public.

Love the show,


GiGi writes:

Hello TWiVers!

I started listening during the pandemic, but have since logged hundreds of hours of listening as I go through the older episodes in order.

I am a first year grad student studying biochemistry, and the main thing I do outside of the lab is rock climbing both indoors and outdoors. Having listened to the clinical updates with Dr. Daniel Griffin and understanding that monkey pox is primarily spread through contact with infected persons or objects (sheets, clothes, etc), what would you recommend for climbers?

We are a sweaty bunch that touch all of the same plastic hand holds in the gym, and the same rocks outdoors. Should the spread of monkeypox via holds be a legitimate concern for climbers?

Gyms have taken vastly different approaches to the Covid-19 pandemic, including mask mandates, limiting the number of people in the gym and only allowing a certain number of problems to be climbed one day, and then leaving them untouched for 14 days before they can be climbed again. Do any of these solutions sound like a good plan of action, or should gyms be open to more creative solutions to keep their climbers safe?

Climbers everywhere would appreciate your wisdom and guidance!


GiGi (she/her)

Philip writes:

Of all the polio cases and all the polio found in waste water, how much is Vaccine Derived Polio vs the Wild Type?

I found TWIV 756 fascinating about the shipping container colony set up to study a couple of new OPV vaccines.  Any updates to report?

Isn’t a non-mutating OPV the only way we will see that virus gone for good?

David writes:

Hello TWIV Folks,

I must stop in every week to hear what some of the coolest people on earth are saying. 

I saw this article last week in Yale Climate Connections, a great source for weather and climate information. It focuses on how nights are warming faster than days, making for a relentless 24 hour heat. 

Thanks for your great work everyone!


Signal Hill CA