Reports of vaccinated people getting infected with COVID-19 might have you wondering about the effectiveness of vaccines to protect you against coronavirus, and how long that protection lasts.

Health authorities in the UK have begun offering a third dose of the COVID-19 jab to people over the age of 50, and those at an increased risk of being infected or getting seriously ill, in a bid to improve their protection.

Similarly, in the US, an FDA advisory panel has recommended booster vaccines be given to all Americans over the age of 65 and those at high risk of severe disease.

Vaccines and effectiveness at preventing severe disease, death

Research shows COVID-19 vaccines remain highly effective at preventing severe disease and death six months after vaccination, including against the highly transmissible Delta variant.

“Consistently, all of the vaccines seem to be doing that with more than 90 per cent effectiveness, including with time,” said Peter Collignon, an infectious diseases physician and microbiologist at the Australian National University.

“[They’re] even better at reducing your risk of dying — probably a 95 to 98 per cent decreased risk.”

“This is currently an epidemic of the unvaccinated,” Professor Collignon said.

Fortunately, most people who get COVID-19 after being vaccinated won’t become very sick, and even fewer will require hospitalisation, said epidemiologist and biostatistician Adrian Esterman from the University of South Australia

How likely am I to get infected?

Other preliminary research suggests there isn’t much difference between the AstraZeneca and Pfizer jab, and that they both reduce the risk of infection by 80 per cent.

Vaccinated people less likely to spread COVID

Real-world evidence shows vaccinated people are able to transmit COVID-19 to others, but it’s thought their risk of doing so is substantially reduced.

“For starters, [vaccinated people] have decreased their risk of giving COVID-19 to others because they’ve reduced their risk of getting infected in the first place,” Professor Collignon said.

“Secondly, [if they do get infected], they tend to have milder disease and have it for a shorter period of time, which also decreases their risk.”