The Oxford University study finds that a longer distance between doses of Pfizer vaccine leads to higher levels of general antibodies.
A longer gap between doses of Pfizer’s COVID-19 vaccine leads to higher overall antibody levels than a shorter gap, a UK study found, but antibody levels are not sustained for long after first dose.
The study led by Oxford University could help inform vaccination strategies against the Delta variant, which reduces the effectiveness of a first dose of the vaccine even if two doses are still protective, and one author said the eight-week deficit in the UK was a ‘sweet spot’ against Delta.
“What we found was, on average, if you had a shorter dosing interval, you had lower antibodies,” Susanna Dunachie, professor of Infectious Diseases at Oxford University and joint researcher of the study told Al Jazeera.
“But this was at a popular level so I think first of all I would like to say that two doses of Pfizer vaccine are very good for inducing immune responses, and if you have had your Pfizer vaccine in a short dosing interval, don’t worry no, it’s a beautiful vaccine. “
The authors emphasized that both the dosing program produced a strong antibody and T cell response in the study of 503 health workers.
“For the longer dosing interval … antibody neutralization levels against the Delta variant were slightly induced after a single dose, and not maintained during the interval before the second dose,” they said. authors of the study.
“After two doses of vaccination, the neutralization levels of the antibodies were twice as high after the longer dosing interval compared to the shorter dosing interval.”
Neutralizing antibodies are thought to play an important role in immunity against coronavirus, but they are not the whole picture, with T cells also playing a part.
The study found that overall T cell levels were 1.6 times lower with a long gap compared to the short dosing interval of 3-4 weeks, but that a higher proportion were “helper” T cells, which support memory. long-term immune system, with long gap.
“While we tend to emphasize neutralizing antibodies as a measure of the immune response … cellular immunity, which is more difficult to measure, is also likely to be very important,” said Peter English, senior. chairman of the British Medical Association (BMA) Public Health Committee on Medicine.
The results, published as a prepress, support the view that while a second dose is needed to provide full protection against Delta, delaying that dose can provide more lasting immunity, even if it is at the cost of short-term protection.
“We found that the UK’s strategy – which was to give a longer dosing strategy, which was based on the knowledge of vaccines for other diseases, and how a longer gap is often better, and also how‘ and a way to quickly kill as many people as possible with one dose – in fact it ended up giving higher levels of antibodies, ”Dunachie told Al Jazeera.
Last December, the UK extended the interval between vaccine doses to 12 weeks, although Pfizer warned that there was no evidence to support a move away from a three-week gap.
The UK now recommends an eight-week gap between vaccine doses to give more people high protection against Delta more quickly, while also maximizing long-term immune responses.