How fast does Covid vaccine protection wear off? New data from the Zoe Covid Study, published today, tries to quantify the extent to which the Pfizer and AstraZeneca vaccines wane over time. It’s a comprehensive study that accounts for PCR test data from over a million double-jabbed people. The results? After roughly six months, Pfizer protection against symptomatic illness fell from 88 per cent to 74 per cent. For AstraZeneca, it was a dip from 77 to 67 per cent after around five months.

It’s important to note what, specifically, this study is measuring. It is a look at infections, not serious illness. In this sense, today’s study isn’t a matter of questioning whether or not vaccines work (on the most important factor, reducing hospitalisations and deaths, evidence continues to suggest protection remains strong), but rather how we should understand the Covid data, and what it means going into the winter months.

Much of how this virus works remains a mystery. But the first country to vaccinate its way out of a Covid emergency, Israel, is now also the first country to be turning out data as to how those vaccines are holding up. Results there are similar to today’s findings. Last month, Pfizer’s CEO Albert Bourla reported that data from Israel showed efficacy against preventing infection fell from over 95 per cent to closer to 85 per cent. In this week’s Spectator magazine, out tomorrow, Anshel Pfeffer looks at Israel’s fourth wave, which is being fuelled by the arrival of the Delta variant.

It’s impossible to draw a direct comparison between Israel’s experience and the UK’s: we have been dealing with the Delta variant for months now, and also decided to leave a longer gap between the first and second vaccine jabs which may create stronger immunity against the virus. But Israel’s experience, as a jabbed country encountering another wave, serves as a reminder that assumptions made earlier this year – that vaccines might bring about a spectacular fall in cases as well as hospitalisations – are now being challenged.

According to Pfeffer, Professor Ran Balicer, who heads the expert committee advising the Israeli health ministry on the pandemic, thinks ‘British colleagues are coming around to our assessment that it has gone down to about 42 per cent effectiveness against infection. We’re still not clear on the effectiveness against illness, but it’s above 80 per cent’. The lead author of today’s study, Professor Tim Spector, (who runs the Zoe Covid symptom app) has said ‘a reasonable worst-case scenario could see protection below 50 per cent for the elderly and healthcare workers by winter’.

If infection protection falls to anything like Professor Balicer’s assessment, this would have major implications for the UK’s Covid policy come winter. First, it strengthens the case for booster shots being administered as quickly as possible, as Britain’s elderly and most vulnerable will most likely have received their first jab over six months ago.

But second, it reconfirms that living with the virus, or as Rishi Sunak once said, living ‘without fear’, is perhaps the only option available. If Nicola Sturgeon was serious in her comments today that restrictions could return in Scotland due to a ‘sharp rise’ in cases, the First Minister may well find that her country will be dipping in and out of lockdown indefinitely. Vaccines aren’t going to eradicate the virus; indeed waning immunity, especially for those who may not be in line for boosters, all but guarantees a rise in cases. This will put pressure on politicians to double down, and restate the purpose of both lockdowns and vaccines: if the link between infections and hospitalisations remains heavily severed, then the jabs are still doing their job.