The rule published on 3 August updates rule 021/2020, of 23 December 2020, with the subject "Vaccination Campaign against Covid-19 - Comirnaty Vaccine" regarding the waiting time between the two doses of the vaccine, which on 1 March had been extended to 28 days.

At the time, the Assistant Secretary of State for Health António Lacerda Sales explained in a press conference that it had been "a decision with broad technical consensus from the General Directorate of Health and Infarmed" and that it would allow the vaccination of 100 thousand more people until the end of March.

On 30 July, the coordinator of the Covid-19 vaccination task force, Vice Admiral Henrique Gouveia e Melo, defended a shortening of the deadline between the two doses of the Pfizer/BioNtech vaccine.

Speaking on the sidelines of an action to promote vaccination with young people, in Parque das Nações, Lisbon, Gouveia e Melo recalled that the deadline between two doses of the AstraZeneca vaccine has already been reduced and defended a similar decision for the Pfizer/BioNtech vaccine, especially with the arrival of one million vaccines from this pharmaceutical company.

In the standard issued on 3 August, the Directorate General of Health updates the vaccination schedule of Comirnaty, recommending that the interval between the two doses is 21 to 28 days.