Extending the interval between Pfizer shots to twelve weeks, may be optimal according to Bloomberg on July 23, 2021. That’s after researchers at University of Birmingham, England studied the records of people who received the wider-spaced shots. They found a longer gap between Pfizer shots considerably increased the peak SARS-CoV-2, spike specific, antibody response.
How the Wider Gap Between Pfizer Shots Came About
The United Kingdom faced a significant surge in known cases of COVID-19 during December 2020. The government there introduced an accelerated vaccination program aimed at giving every citizen one dose of Pfizer as soon as possible.
However, COVID vaccines were still in relatively short supply. And so it decided to space the first and second doses twelve weeks apart, instead of the then-recommended three.
This created a unique opportunity to study the effect of a wider gap between Pfizer shots in a large group of vaccinated people. And to compare what they found with those who had followed a three-week Pfizer program.
The Optimal ‘Sweet Spot’ for Delta Is Eight Weeks
The findings we summarize below are preliminary, and subject to review by peers. None the less they do suggest the following, according to UK national broadcaster BBC News:
1… Short and long intervals both ‘generated strong immune responses overall’. The antibody levels ‘dipped after the first dose … but levels of T-cells remained high’.
2… However, the shorter interval ‘generated fewer of the neutralizing antibodies that can bind the virus and stop it infecting cells’.
3… While the longer interval led to fewer T-cells overall. But there were more ‘helper T-cells … which support immune memory’
However, informed clinical opinion favors an eight-week interval, over the full twelve weeks. That’s because it’s ‘the best trade-off’ between getting as many people fully vaccinated as quickly as possible, and allowing the population to produce higher antibody levels.
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Preview Image: Distribution of COVID-19 Vaccines
