Thread by @michaelmina_lab

Wondering if you should get your baby the new RSV shot?

I’ve studied respiratory viruses like RSV, and their vaccines and treatments for years

Here’s a 🧵 of key info

We just had a baby last week

We chose to protect our newborn with it

And we’re lucky we could get a dose

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1) First and most critical is that the new RSV shot is very protective against RSV

In large placebo controlled “gold standard” trials it was ~75% effective to prevent RSV requiring medical attention in babies

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nejm.org/doi/full/10.10…

2. It’s Safe

There were no indications of increased serious adverse events associated with the shot

In fact, there was a very small decrease in the number of serious adverse events in those who received the shot compared to those who got placebo

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3) Although a lot of people, including doctors, refer to the new RSV shot as a “vaccine”

It is NOT a vaccine

It does not elicit immune memory
against RSV

It IS a shot of a *monoclonal antibody* against RSV

So, for ex., it wont cause a short fever like many vaccines do

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This is important bc the RSV shot is more temporary than most vaccines

The antibodies delivered in the shot are *all you get* - no extra antibodies are created by immunity

It’s most potent over first 3 months

That means it’s best to get near RSV season

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4) although many people hadn’t been aware of RSV until recently bc COVID raised overall awareness

it is a dangerous virus especially for babies and young children w >50,000 young children hospitalized in US each winter and hundreds of deaths

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5) Getting RSV in the first year of life also increases risk of being diagnosed with asthma

Those who avoided RSV in their first year of life had 25% less chance of being diagnosed with asthma (the mechanisms are still being explored)

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thelancet.com/journals/lance…

6) The RSV monoclonal antibody shot for babies is made by Sanofi. it is called Beyfortus or Nirsevimab

Fortunately it has been in high demand (bc it helps keep babies healthy)

Unfortunately manufacturing supply hasn’t been able to keep up so it is difficult for some to get

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CDC & others are working to try to ensure that supply can be fairly shared across the US (and world). Sanofi is working hard (from what I hear) to increase supply quickly

So if it’s offered, I wouldn’t recommend thinking about it until the next visit, the doses are limited

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7) Summary

RSV can cause serious disease in babies and increases risk of long term issues like asthma

The new RSV shot is highly protective

It’s not a vaccine but a monoclonal antibody

It is most effective for a few months

Supply is limited - if it’s offered, act fast

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8) additional info:

The monoclonal antibody that makes up the new RSV shot is an antibody that binds a part of RSV virus called the Fusion or ‘F’ protein

When the antibody ‘sees’ RSV, it binds ‘F’ and neutralizes RSV - preventing it from infecting cells in the body

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This is similar to infusions of monoclonal antibodies against the spike protein for COVID-19

However, unlike COVID, RSV is not likely to evade the antibodies in Beyfortus bc the site they recognize is highly conserved (can’t change easily). (and pop pressure is much lower)

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