Thread by @ScienceUpFirst

No vaccine is perfect. That includes the COVID-19 vaccines.

But they don’t need to be in order to save millions of lives.

A thread about transmission 👇

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#ScienceUpFirst

Transmission is the passing of a disease-causing pathogen (like a virus) from an infected person to someone else.

COVID-19 vaccines directly and indirectly reduce the transmission of COVID-19.

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COVID-19 vaccines can directly reduce transmission by stopping your body from passing on live copies of the virus.

Vaccines were good at interrupting transmission of the Alpha/Delta variants. How well they stop Omicron transmission is being studied.

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Bad news: Omicron can transmit between vaccinated people.

Good news: That transmission might be reduced if you’re vaccinated.

At least one study found infected individuals with 3 doses do seem to have lower viral loads.

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Vaccines also indirectly reduce transmission by interrupting infection itself.

If you never develop COVID-19, you can’t pass it on.

Boosters reduce the risk of an Omicron infection. 2 doses help protect against infection, but to a lesser extent.

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Remember: COVID-19 vaccines do not need to completely stop transmission to be effective.

COVID-19 vaccines remain excellent at protecting against severe disease and hospitalization. 2 doses means you are 5X less likely to be hospitalized.

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Few vaccines give “sterilizing immunity”

Sterilizing immunity, meaning complete protection against infection, is the “holy grail” of vaccines. But sterilizing immunity is not necessary to reduce disease in a population.

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For example, the rotavirus vaccine does not prevent infection, but it has reduced rotavirus hospitalizations by 63-94% since it was introduced in 2006.

No vaccine is 100% effective, and yet vaccines prevent an estimated 4-5 million deaths every year.

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Scientists are look at new strategies!

One possibility is vaccines that are better at targeting the primary point of contact of SARS-CoV-2: the respiratory tract. A vaccine given nasally could better target this area and help reduce transmission!

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COVID-19 vaccines *do* help reduce transmission.

Completely stopping transmission is not needed for vaccines to be effective.

Layering protection, increasing vaccine uptake, and investigating new strategies are all tools to fight the pandemic.

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Questions about vaccines? We are here to help!

References: tinyurl.com/SUFTransmission

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