Explainer: What is a Covid-19 vaccine 'breakthrough' case?

  • Although the coronavirus jab is very effective at preventing illness, it’s still possible to contract the virus - you’re just less likely to get very sick
  • Nearly all Covid hospitalisations and deaths in the US were people who did not get vaccinated
Associated PressYP |

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A healthcare worker prepares a dose of the Johnson & Johnson coronavirus vaccine during the opening of a public vaccination programme in New York City. Photo: Reuters

What is a Covid-19 vaccine “breakthrough” case?

It’s when a fully vaccinated person gets infected with the coronavirus.

Studies have shown the two-dose Covid-19 vaccine by Pfizer is around 95 per cent effective at preventing illness, though the Sinovac jab has a lower efficacy rate of around 50.7 per cent.

You might need a booster shot sometime soon

However, though the vaccines are good at protecting us from the virus, it’s still possible to get infected with mild or no symptoms, or even to get very sick.

If you do end up getting sick despite vaccination, experts say the shots help reduce the severity of the illness - which is the main reason to get vaccinated.

But the understanding of how vaccinated people who are infected might spread the virus to others is changing.

FYI - even if you’re vaccinated, it’s a good idea to mask up!

Previously, health officials believed vaccinated people who get breakthrough infections were unlikely to spread the virus. But with the more contagious delta variant now dominant, the US Centres for Disease Control and Prevention said new data shows people who get infected could carry enough of the virus in their nose and throat to spread it to others.

The agency cited the data when it updated its guidance to say vaccinated people should go back to wearing masks indoors in areas where the virus is surging.

“It is concerning enough that we feel like we have to act,” said CDC Director Dr. Rochelle Walensky.

Still, health experts say the vaccines provide strong protection against serious illness. In the US, people who weren’t vaccinated make up nearly all hospitalisations and deaths from Covid-19.

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