This content was published on Jul 23, 2021 – 00:56
LONDON (Reuters) – A longer interval between two doses of Pfizer’s COVID-19 vaccine provides a higher level of antibodies compared to a shorter interval, despite a sharp drop in antibody levels after the first dose, a British study found.
The study may help design vaccination strategies against the delta variant, which reduces the effectiveness of the first dose of the Covid-19 vaccine, even though two doses are effective in protecting.
For the longer dose range, neutralizing antibody levels against the delta variant were weakly induced after one dose, and were not maintained throughout the range until the second dose, the authors of the Oxford University study noted. .
“After two doses of the vaccine, neutralizing antibody levels were twice as high after the longest dose period compared to the shortest dose period.”
Neutralizing antibodies are important in the role of building immunity against the coronavirus, but they do not act alone, as T cells also play a role.
The study found that overall levels of T cells were 1.6 times lower with a longer interval compared to the shorter 3-4 week schedule, but the highest percentage were ‘helper’ T cells, which strengthen immune memory.
The authors confirmed that either band produced a potent antibody and T-cell response in a study of 503 healthcare professionals.
The results, released in a preprint study, support the view that while a second dose is needed to ensure complete protection against the delta variant, delaying the dose may provide long-lasting immunity, even if it means less protection in the short term.
In December last year, the UK extended the interval between vaccine doses to 12 weeks, although Pfizer cautioned that there was no evidence to support changing the original proposed three-week interval.
The UK today recommends an 8-week gap between two doses of the vaccine so that more people are protected from the delta variant more quickly, while still maximizing long-term immune responses.
“I think 8 weeks is the right time,” Susanna Donacci, a researcher who co-led the study, told reporters.
(Reporting by Alistair Smoot)
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