Two studies, one published in The New England Journal of Medicine and the other, the CDC's Morbidity & Mortality Weekly Report (MMWR), find that vaccination against COVID-19 effectively protects children and adolescents aged 12-18 years from both infection and severe disease. Both papers cover periods when the more transmissible Delta variant was dominant. Paediatrician Ángel Hernández Merino assesses these results.

A study published in Science Translational Medicine shows that pregnant women are more dependent on a second dose of vaccine to develop a full immune response. The work sheds light on how pregnancy affects immunity against SARS-CoV-2, a question still little studied. Obstetrician Mar Gil stresses the importance of getting pregnant women vaccinated, and of their inclusion in clinical trials.

A study of more than 700,000 people in Sweden analysed the effectiveness of the heterologous schedule, combining the AstraZeneca vaccine with another dose of a messenger RNA vaccine, with the traditional homologous schedule, consisting of two doses of AstraZeneca. The results showed increased protection against SARS-CoV-2 infection when two different vaccines were combined.

The European Medicines Agency issued its recommendations yesterday afternoon regarding the administration of a third dose of the Comirnaty (Pfizer/BioNTech) and Spikevax (Moderna) vaccines. These are the reactions of several experts on the matter.

Johnson & Johnson has just released preliminary data from its two-dose trial in a press release. It shows that the second dose increases the antibody response and also confirms the duration of protection among those who received one dose.