The initial protection offered from both the Pfizer and AstraZeneca vaccines make the case for getting vaccinated against COVID-19 is irrefutable. Crucially, the vaccines have proven to deal a decisive blow to the Delta strain that is far more transmissible than earlier mutations. However, evidence has shown that the efficacy of the vaccines wane the further away you get from your second dose.
This concerning trend has led many experts to make gloomy forecasts about winter, where high-risk individuals could be vulnerable to a resurgent virus.
In a recent video, professor Tim Spector, lead scientist at the ZOE COVID Study, explained the time interval after your second Covid vaccine dose that leaves you more “worse off” against Delta.
He based his assertions on more than 1.2 million test results and participants, which represented the largest real-life vaccine effectiveness studies on record.
To determine the second dose effectiveness, or how long people are protected, the researchers looked to see whether any of these people reported a positive COVID test result between May 26 this year, when the Delta variant became dominant in the UK, and the end of July.
It’s important to note that these figures have been adjusted to give an average risk of infection reduction across the population.
“But because we are all unique and our immune systems may respond in different ways to the vaccine, there will be variation in individual levels of immunity and infection risk,” the study researchers noted.
How the findings compare to other reports
The six month safety and effectiveness trial of the Pfizer vaccine, which were carried out when the original Alpha variant was dominant, showed that the jab provided a 96.2 percent reduction in infection risk up to two months after the second dose, with an 83.7 percent reduction after more than four months.
In contrast, the ZOE study findings show that in the real world there is a slightly lower level of protection to start with, as well as a more pronounced wane over time.
This could be for many reasons, including a greater number of people with underlying health conditions in the general population compared to trial participants and variability in how the vaccines were stored and administered, the research team pointed out.
“This means that the majority of people who had their second dose five to six months ago will be older or vulnerable due to other health reasons, placing them at increased risk of COVID-19 compared to those vaccinated more recently.”
It must be emphasised that the vaccines still provide high levels of protection for the majority of the population, especially against the Delta variant, so we still need as many people as possible to get fully vaccinated.
Importantly, not only does your vaccine help to protect you, it also protects those around you who aren’t yet vaccinated.
This includes children and people with weakened immune systems who don’t respond as well to the vaccine.
COVID-19 vaccines are available for:
- Everyone aged 16 or over
- Some children aged 12 to 15 who have a higher risk of getting seriously ill from COVID-19 or who live with someone at high risk of catching it.
If you’re aged 18 or over (or will turn 18 within three months) you can:
- Book your COVID-19 vaccination appointments online for an appointment at a vaccination centre or pharmacy
- Find a walk-in COVID-19 vaccination site to get vaccinated without needing an appointment
- Wait to be contacted by your GP surgery and book your appointments with them.