“We are exploring co-administering our ‘pneumococcal’ vaccine candidate Prevnar-20 * with a third dose of our Covid-19 vaccine. If successful and approved, people could receive both vaccines.” This was announced by Albert Bourla, Pfizer’s president and CEO, announcing the launch of an ad hoc study on Twitter. The trial will involve 600 adults, informs the US giant in a note. The main objective is to evaluate the safety of the two vaccines when administered simultaneously, with a follow-up of 6 months after vaccination. The secondary goal is to measure the immune responses induced by each of the two vaccines. (continues) The 600 adults, aged 65 or over – specifies the American company – will be recruited from the participants in the phase 3 clinical trial on the Pfizer / BioNTech anti-Covid vaccine, who received the second dose at least 6 months before entering the co-administration study.Enrollees will be randomly divided into 3 groups: 20-valent pneumococcal conjugate vaccine (20vPnC) plus anti-Covid booster (third dose), 20vPnC plus placebo, anti-Covid booster plus placebo.