So you are vaccinated. What risk are you really facing now?

UK data suggests if the infected person is vaccinated with two doses of Pfizer vaccine, they are half as likely to transmit Delta to their contacts; for AstraZeneca, they are about 25% less likely.

Combined, these two layers produce a very substantial reduction in the risk of transmission: a 79% reduction for AstraZeneca and a 93% reduction for Pfizer, according to an analysis conducted by the Doherty Institute.

“If you have brand combinations, it will be somewhere in between,” says associate professor James Wood, infectious disease modeler at the University of NSW. “The simple message is this: vaccines work very well against transmission and serious disease. “

Third, the uninfected person is protected against their infected friend because they too are vaccinated.

Additional defenses, like masks and hand washing, go even further. An editorial has just appeared in the British medical journal, written by Professor Paul Glasziou of Bond University, suggested that the best evidence was that wearing a mask, for example, reduced the relative risk by 10%.

However, this overall risk is an average. Some people will be at greater or lesser risk of infection – and others will be at greater or lesser risk of poor results if they become ill.

“We are faced with a classic problem. The risks are quantified at the population level, ”said Dr Claire Hooker, infectious disease risk communication specialist at the University of Sydney.

The numbers are an average and “don’t tell you as an individual where you’re going to land on the bell curve,” she said.

For example, all vaccines are less protective of the most vulnerable and the elderly against infection.

The effectiveness of vaccines also changes over time. A person two weeks after their second jab has maximum protection; Pfizer’s vaccine drops 93% in effectiveness to 53 percent after four months.

Then comes the question of serious illness and hospitalization.

AstraZeneca offers between 88 and 94 percent efficiency and Pfizer between 75 and 100 percent.

Protection also varies by age and length of time since vaccination, but far less than protection against infection.

For people aged 40 to 64, Pfizer offers 95% effectiveness against serious illness or hospitalization, even after five months.

But for people over 65, that drops to 90 percent. For people over 65 classified as “extremely vulnerable”, this drops to 71%.

Determining whether these risks are worth it is tricky and requires clear thinking, Dr Hooker said.

“Would it be an area of ​​insane regret for me if I brought COVID home to my elderly mother and she fell seriously ill? “

If we wanted to keep the risk at zero, we could never all leave the house. But most people want to go back to something that’s approaching normal life, Dr. Hooker said.

“I bought theater tickets. I can not wait. I’m going to go and don’t worry it will mean my kids, who are going there, will get COVID. I accept the degree of risk, and the fact that luck will be involved. My decision on the quality of life and the things that give me joy.

Liam Mannix’s Examiner newsletter explains and analyzes science with a rigorous emphasis on evidence. Sign up to get it every week.