RPS statement on change in COVID-19 vaccine dosing interval

The COVID-19 vaccination programme is a vital part of the pandemic response. The change in the planned interval between currently licensed vaccine doses has raised concerns, but it is a decision that is strongly supported by the Royal Pharmaceutical Society because it will protect more people more rapidly.

Currently, licensed COVID-19 vaccines help prevent an individual developing COVID-19 disease (it is not known yet if the vaccine prevents viral transmission). 

Clinical trial data show that substantial protection from developing COVID-19 is given from the first dose of the vaccine. A booster dose is essential for long-term protection, but this booster dose can be given later to enable more of the population to receive the initial dose quickly. 

This strategy will protect a greater number of people from COVID-19 disease.

Key sources of information that informed the RPS decision

Letter of the Joint Chief Medical Officers which explains that:

  • The first dose of both vaccines provides substantial protection against COVID-19, and in particular against severe disease, within 2-3 weeks of vaccination
  • Protecting twice the number of people in the next few months is preferable to giving half the number of people a slightly greater level of protection.

The second dose is very important for duration of protection but the greatest majority of protection from clinical disease comes from the first dose.

Read the full letter

Statement from the Joint Committee on Vaccination and Immunisation (JCVI) which advises:

  • With most vaccines an extended interval between the prime and booster doses leads to a better immune response to the booster dose. This was seen with the AstraZeneca trial (see below)
  • There is currently no strong evidence to expect that the immune response from the Pfizer-BioNTech vaccine would differ substantially from the AstraZeneca and Moderna vaccines
  • JCVI advises a maximum interval between the first and second doses of 12 weeks.

Read the full statement

Regulatory approval for the AstraZeneca vaccine

  • The recommended dosage is two doses with the second dose “administered between four and 12 weeks after the first dose”, not 21 days apart.

Read the full regulatory approval

Clinical trial data for the AstraZeneca vaccine

  • Results were generalisable across two diverse settings with different timings for the booster dose (Brazil, booster dose with six weeks, and UK, booster dose more than 12 weeks after the first dose).

See the full trial data

Regulatory approval for Pfizer-BioNTech vaccine

  • The recommended dosage is two doses “at least 21 days apart”, not exactly 21 days apart
  • The clinical trial had a planned interval between doses of 21 days, but participants actually received their second vaccination 19 to 42 days after the first vaccination.

Read the full regulatory approval

British Society for Immunology statement

  • Most immunologists agree that delaying a booster dose of a protein antigen vaccine by eight weeks would be unlikely to have a negative effect on the overall immune response post-boost.

Read the full statement

World Health Organisation statement

  • WHO recommended on 8 January 2021 that the interval between doses of the Pfizer/BioNTech vaccine may be extended up to 42 days (6 weeks).

Read the full statement