By Alistair Smout

LONDON (Reuters) -COVID-19 vaccines made by Pfizer (NYSE: Moderna (NASDAQ): Companies using mRNA tech provide the highest boost to antibody levels when administered 10-12 week after receiving the second dose. A new British study found this.

British officials referred back to “COVBoost”, when they said that Moderna was preferred by the country for its booster campaign. But, this data is not yet publicly accessible.

Six of seven boosters were found to increase immunity following initial vaccination with Pfizer BioNTech’s vaccine. All seven boosters increased immunity when administered after receiving two doses AstraZeneca’s vaccine (NASDAQ:).

A third dose of many of the vaccines that we have tested will work in many combinations, Professor Saul Faust of University of Southampton (the trial’s leader) told reporters.

A study published Thursday evening found that Moderna or Pfizer gave strong results in increasing antibody and T cell levels. This was regardless of whether the patient had previously received AstraZeneca, Pfizer, or both.

Professor Eleanor Riley of Edinburgh University, immunologist stated that “all four of these vaccination regimens are going to produce essentially the exact same level of immunity” and would likely be equal in effectiveness. The data also support a change in policy regarding booster gaps.

“These data support earlier this week’s decision by the JCVI, vaccine committee, to extend booster doses up to three months from the date of second vaccination.”

When AstraZeneca, Novavax (NASDAQ:), Johnson & Johnson (NYSE:) and Curevac were given as boosters, they increased antibody levels for either initial vaccine, albeit to a smaller degree, the study found. While Valneva increased antibodies in those who were initially vaccinated by AstraZeneca (NYSE:), it didn’t provide any boost to Pfizer.

Faust stated that he shared Omicron samples with UK Health Security Agency in order to create data about it.

However, the study found that booster shots could also be used to increase T-cell responses against Beta and Delta versions. This may have a significant role in long-term protection.

A second study published by Imperial College London on how SARS-CoV-2 initial exposure affects immune responses was also published late Thursday. It found that both Alpha as well as Delta T-cell responses were similar to those seen after vaccination.